Hardest Trivia Questions Quiz On USMLE
What we have here is the hardest trivia questions quiz on USMLE. Medical practitioners are selfless and do everything possible to save the life of their patients with their underlying oath being that they cannot harm. For you to prove that you understand what is expected of you as a medical practitioner by your patients, you will need to pass the medical licensing exams.
Questions and Answers
- 1.
A normal, healthy, 25-year-old man lives at the beach. His twin brother has been living in a mountain cabin for the past 2 years. Which of the following indices would be expected to be higher in the man living at sea level?
- A.
Diameter of pulmonary vessels
- B.
Erythropoietin production
- C.
Mitochondrial density in a muscle biopsy
- D.
Renal bicarbonate (HCO3-) excretion
- E.
Respiratory rate
Correct Answer
A. Diameter of pulmonary vesselsExplanation
A number of physiologic changes occur in a person living at high altitude. The diminished barometric pressure at high altitude causes alveolar hypoxia and arterial hypoxia. Pulmonary vasoconstriction occurs in response to alveolar hypoxia; therefore, the diameter of the pulmonary vessels would be greater in the brother living at sea level. All the other choices describe physiologic processes that would be enhanced by living at high altitude. Increased erythropoietin production (choice B), caused by arterial hypoxia, leads to increases in hematocrit in people living at high altitude. Mitochondrial density increases (choice C) in people chronically exposed to the hypoxemia caused by living at high altitude. At high altitudes, the ventilation rate increases, causing a respiratory alkalosis. The kidney then compensates by increasing the excretion of HCO3- (choice D). Increasing the rate of respiration (choice E) is a very useful adaptation to the hypoxic conditions of high altitude. The primary stimulus is the hypoxic stimulation of peripheral chemoreceptors.Rate this question:
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- 2.
A woman presents to a dermatologist because she has lost almost all the hair on her body, including scalp hair, eyebrows, eyelashes, armpit, and groin hair, and the fine hairs on her body and extremities. Does she most likely have a variant of which of the following?
- A.
Alopecia areata
- B.
Androgenic alopecia
- C.
Chronic cutaneous lupus erythematosus
- D.
Lichen planopilaris
- E.
Trichotillomania
Correct Answer
A. Alopecia areataExplanation
Alopecia areata is caused by an autoimmune attack on hair follicles. It has a wide range of clinical severity, with most cases involving a localized patch of hair (which regrows within 1 year in half of the patients). The hair that does regrow may be gray or depigmented. More severe cases can involve the entire scalp (alopecia totalis) or, as in this patient, the entire body surface (alopecia universalis). These more severe cases are less likely to resolve adequately. Treatment of alopecia areata is often unsuccessful, but topical steroids are typically tried. Androgenic alopecia (choice B) is common male pattern baldness. Chronic cutaneous lupus erythematosus (choice C) can produce localized baldness. Lichen planopilaris (choice D) can produce localized baldness. Trichotillomania (choice E), also called traumatic alopecia, is alopecia due to trauma, such as hair pulling or tight braids.Rate this question:
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- 3.
The greater omentum is derived from which of the following embryonic structures?
- A.
Dorsal mesoduodenum
- B.
Dorsal mesogastrium
- C.
Pericardioperitoneal canal
- D.
Pleuropericardial membranes
- E.
Ventral mesentery
Correct Answer
B. Dorsal mesogastriumExplanation
Both the omental bursa and the greater omentum are derived from the dorsal mesogastrium, which is the mesentery of the stomach region. The dorsal mesoduodenum (choice A) is the mesentery of the developing duodenum, which later disappears so that the duodenum and pancreas come to lie retroperitoneally. The pericardioperitoneal canal (choice C) embryologically connects the thoracic and peritoneal canals. The pleuropericardial membranes (choice D) become the pericardium and contribute to the diaphragm. The ventral mesentery (choice E) forms the falciform ligament, ligamentum teres, and lesser omentum.Rate this question:
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- 4.
A 34-year-old woman has prescribed an antidepressant, which she has taken for the past 3 months. She is on no other medications and is in generally good health. After attending a party, at which she consumed wine and cheese, she is rushed to the emergency room with tachycardia, headache, and blood pressure of 200/100. Which antidepressant is she most likely taking?
- A.
Amitriptyline
- B.
Fluoxetine
- C.
Phenelzine
- D.
Sertraline
- E.
Trazodone
Correct Answer
C. PhenelzineExplanation
Wine and cheese (and many other fermented foods) contain tyramine, an indirect sympathomimetic that can trigger excess
catecholamine release and lead to a hypertensive crisis when ingested by patients taking MAO inhibitors. The only such drug listed among the answer choices is phenelzine. Other MAO inhibitors with similar effects include tranylcypromine, isocarboxazid, and iproniazid. Whenever this particular drug class is mentioned in a question stem, consider the possibility of interactions with foods or other medications the patient may have taken. Amitriptyline (choice A) is a tricyclic antidepressant. Tricyclic antidepressant drugs (particularly amitriptyline) are known for their anticholinergic side effects. They also produce postural hypotension (because they block alpha-adrenergic receptors) and are sedative. Fluoxetine and sertraline (choices B and D) are antidepressants that are selective serotonin reuptake inhibitors (SSRIs). Fluoxetine is also useful in treatment of obsessive-compulsive disorders. Trazodone (choice E) is an atypical antidepressant with substantial sedative side effects. Its most serious side effect is priapism, a medical emergency.Rate this question:
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- 5.
Which of the following hormones is secreted by anterior pituitary cells that stain with acidic dyes?
- A.
ACTH
- B.
FSH
- C.
LH
- D.
Prolactin
- E.
TSH
Correct Answer
D. ProlactinExplanation
The cells of the anterior pituitary can be classified as chromophils (love dyes) or chromophobes (do not stain with dyes). The chromophils can be further divided into acidophils (stain with acidic dyes) and basophils (stain with basic dyes). The acidophils include the somatotropes, which secrete growth hormone, and the mammotropes, which secrete prolactin. The basophils include the corticotropes, which secrete ACTH (choice A), the gonadotropes, which secrete FSH and LH (choices B and C), and the thyrotropes, which secrete TSH (choice E).Rate this question:
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- 6.
A 23-year-old male graduate student gets into a serious argument with one of his college professors, making a physical threat to the professor, and necessitating a call to campus security. The argument was precipitated by an incident between the professor and the student's girlfriend; when the professor corrected the student's girlfriend in class, the student felt the professor was verbally abusive. Which of the following is the most likely diagnosis?
- A.
Dependent personality disorder
- B.
Histrionic personality disorder
- C.
Narcissistic personality disorder
- D.
Paranoid personality disorder
- E.
Passive aggressive personality disorder
Correct Answer
D. Paranoid personality disorderExplanation
Persons with this condition often perceive attacks and danger in relatively innocuous situations. They are quick to respond with anger, and, because personality disorders are ego-syntonic, individuals with personality disorders do not believe themselves to be in error. The individual with dependent personality disorder (choice A) does not confront others but wants others to take care of him. The individual with histrionic personality disorder (choice B) is flamboyant and seductive, not confrontational and angry. The individual with narcissistic personality disorder (choice C) is characterized by feelings of entitlement because they are so "special." And the individual with passive aggressive personality disorder (choice E) expresses anger indirectly (e.g., always being late) rather than confrontingRate this question:
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- 7.
Which of the following would shift the oxygen-hemoglobin dissociation curve to the right?
- A.
Carbon monoxide poisoning
- B.
Decreased PCO2
- C.
Decreased pH
- D.
Decreased temperature
- E.
Decreased 2,3-DPG
Correct Answer
C. Decreased pHExplanation
The loading of O2 is facilitated when the oxygen dissociation curve shifts to the left, and the unloading of O2 is facilitated when the oxygen dissociation curve shifts to the right. A good way to remember the conditions that promote dissociation of O2 is to think of exercising muscle, which has decreased pH (choice C) because of the accumulation of lactic acid, increased PCO2 (compare with choice B) because of the increased rate of aerobic metabolism, increased temperature (compare with choice D), and increased 2,3-DPG (2,3-diphosphoglycerate; compare with choice E) because of increased glycolysis. Carbon monoxide poisoning (choice A) left-shifts the oxygen dissociation curve, which interferes with the unloading of O2. Carbon monoxide also strongly binds to available sites on hemoglobin.Rate this question:
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- 8.
The wife of a 48-year-old male patient brings him to the emergency room and says that his memory has progressively gotten worse over the last several years. She also says his personality has been changing. The physician notes abnormal writhing movements of the man's limbs and hyperreactive reflexes. MRI reveals a loss of volume in the neostriatum and cortex. This disease is inherited via an
- A.
Autosomal dominant trait
- B.
Autosomal recessive trait
- C.
X-linked dominant trait
- D.
X-linked recessive trait
Correct Answer
A. Autosomal dominant traitExplanation
This patient has Huntington's disease, which has autosomal dominant inheritance. It is characterized by severe degeneration of the caudate nucleus along with degenerative changes in the putamen and cortex. In addition to chorea, these patients frequently suffer from athetoid (writhing) movements, progressive dementia, and behavioral disorders.Rate this question:
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- 9.
A man presents to a dermatologist because of a severe mucocutaneous rash that involves most of his body, including his palms and soles. Questioning reveals that he is a merchant marine who several months previously had an encounter with a prostitute in Southeast Asia. Which of the following is the most likely causative agent of this rash?
- A.
Herpes simplex I
- B.
Herpes simplex II
- C.
HIV
- D.
Neisseria gonorrhoeae
- E.
Treponema pallidum
Correct Answer
E. Treponema pallidumExplanation
The rash described is that of secondary syphilis, caused by Treponema pallidum. Involvement of palms and soles by a rash is unusual, and secondary syphilis should come to mind. Not all patients with secondary syphilis have a severe form of the rash, and consequentially some cases are missed. Primary syphilis takes the form of a painless, button-like mass called chancres. Tertiary syphilis, which is now rare, has a propensity for involving the aorta and central nervous system and can also cause "gummas" (granulomatous-like lesions) in many sites, notably including liver and bone. Herpes simplex I (choice A) usually causes perioral vesicular lesions. Herpes simplex II (choice B) usually causes genital vesicular lesions. HIV (choice C) does not itself cause a rash, although co-infection with other organisms can result in a rash. Neisseria gonorrhoeae (choice D) does not typically cause a rash.Rate this question:
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- 10.
A patient with familial hypercholesterolemia undergoes a detailed serum lipid and lipoprotein analysis. Studies demonstrate elevated cholesterol in the form of increased LDL without elevation of other lipids. This patient's hyperlipidemia is best classified as which of the following types?
- A.
Type 1
- B.
Type 2a
- C.
Type 2b
- D.
Type 3
- E.
Type 5
Correct Answer
B. Type 2aExplanation
Hyperlipidemia has been subclassified based on the lipid and lipoprotein profiles. Type 2a, which this patient has, can be seen in a hereditary form, known as familial hypercholesterolemia, and also in secondary, acquired forms related to nephritic syndrome and hyperthyroidism. The root problem appears to be a deficiency of LDL receptors, which leads to a specific elevation of cholesterol in the form of increased LDL. Heterozygotes for the hereditary form generally develop cardiovascular disease from 30 to 50 years of age. Homozygotes may have cardiovascular disease in childhood. Type 1 (choice A) is characterized by isolated elevation of chylomicrons. Type 2b (choice C) is characterized by elevations of both cholesterol and triglycerides in the form of LDL and VLDL. Type 3 (choice D) is characterized by elevations of triglycerides and cholesterol in the form of chylomicron remnants and IDL. Type 5 (choice E) is characterized by elevations of triglycerides and cholesterol in the form of VLDL and chylomicrons.Rate this question:
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- 11.
A mutation affecting the development of the diencephalon could interfere with the secretion of which of the following hormones?
- A.
Adrenocorticotrophic hormone (ACTH)
- B.
Epinephrine
- C.
Oxytocin
- D.
Prolactin
- E.
Thyroid stimulating hormone (TSH)
Correct Answer
C. OxytocinExplanation
The neurohypophysis (posterior pituitary) is derived from an evagination of diencephalic neurectoderm. This structure is responsible for releasing oxytocin and vasopressin to the general circulation. Both hormones are synthesized in cell
bodies contained within the hypothalamus. ACTH (choice A), prolactin (choice D), and TSH (choice E) are all synthesized and released by the anterior pituitary, or adenohypophysis, which is derived from an evagination of the ectoderm of Rathke's pouch, a diverticulum of the primitive mouth. Remnants of this pouch may give rise to a craniopharyngioma in later life. EpinephrineRate this question:
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- 12.
Which of the following organisms is the most common cause of community-acquired pneumonia?
- A.
Chlamydia pneumoniae
- B.
Haemophilus influenzae
- C.
Mycoplasma pneumoniae
- D.
Staphylococcus aureus
- E.
Streptococcus pneumoniae
Correct Answer
E. Streptococcus pneumoniaeExplanation
The most common bacteria implicated in community-acquired pneumonia is the pneumococcus, Streptococcus pneumoniae. Other organisms frequently implicated in patients less than age 60 without comorbidity include Mycoplasma pneumoniae, respiratory viruses, Chlamydia pneumoniae, and Haemophilus influenzae. When community-acquired pneumonia occurs in elderly patients or patients with comorbidity, aerobic gram-negative bacilli and Staphylococcus aureus are added to the list. The organisms listed in choices A, B, and C are important causes of community-acquired pneumonia, but are not the most frequent causes. Staphylococcus aureus (choice D) is an important cause of community-acquired pneumonia (particularly in the elderly and in patients with comorbidity), but is not the most frequent cause.Rate this question:
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- 13.
A 54-year-old male with acute lymphocytic leukemia develops a blast crisis. He is treated with intensive systemic chemotherapy. Following treatment, the patient will be at increased risk for the development of
- A.
Bile pigment gallstones
- B.
Cholesterol gallstones
- C.
Cystine kidney stones
- D.
Struvite kidney stones
- E.
Uric acid kidney stones
Correct Answer
E. Uric acid kidney stonesExplanation
Uric acid kidney stones in patients with leukemia are secondary to increased production of uric acid from purine breakdown during periods of active cell proliferation, especially following treatment. Vigorous hydration and diuresis are generally instituted after the diagnosis of acute leukemia is made. Uric acid kidney stones are also associated with inborn errors of purine metabolism, such as gout. Pigment gallstones (choice A) are associated with hemolytic disease. The incidence of this type of gallstone is not increased in treated leukemias. Cholesterol gallstones (choice B) are associated with diabetes mellitus, obesity, pregnancy, birth control pills, and celiac disease. Cystine kidney stones (choice C) are rare; they are found in cystinuria. Struvite kidney stones (choice D) are associated with infection by urea-splitting organisms, such as ProteusRate this question:
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- 14.
A 65-year-old man with mild heart failure is treated with a loop diuretic . A few days later the man complains of muscle weakness. Laboratory results are shown below. Arterial PCO2: 48 mm Hg Arterial pH: 7.49 Plasma HCO3-: 35 mEq/L Which of the following is most likely decreased in this man?
- A.
Plasma aldosterone
- B.
Plasma potassium
- C.
Potassium excretion
- D.
Renin secretion
- E.
Sodium excretion
Correct Answer
B. Plasma potassiumExplanation
The data shown in the table indicate that the man has developed metabolic alkalosis (increased PCO2, pH, and HCO3-), which occurs commonly with overuse of diuretics (thiazides and loop diuretics). The overuse of a loop diuretic increases the excretion of sodium (choice E) and potassium (choice C) by the kidneys. The increase in potassium excretion leads to a decrease in plasma potassium levels (choice B). The decrease in plasma potassium stimulates aldosterone secretion, which raises plasma aldosterone levels (choice A). The sodium depletion stimulates renin secretion (choice D), which in turn raises angiotensin II levels in the plasma (which also stimulates aldosterone secretionRate this question:
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- 15.
A 27-year-old white male presents with a 3-week history of several swollen and painful toes and knees. He has a past history of conjunctivitis. He also describes some low back stiffness that is more severe in the morning. Which of the following is the most likely diagnosis?
- A.
Gout
- B.
Lyme disease
- C.
Reiter's syndrome
- D.
Rheumatoid arthritis
- E.
Septic arthritis
Correct Answer
C. Reiter's syndromeExplanation
This is a case of Reiter's syndrome. Patients typically present with the acute onset of arthritis (usually asymmetric and additive), with involvement of new joints occurring over a period of a few days to 2 weeks. Joints of the lower extremities are the most commonly involved, but wrists and fingers can also be affected. Dactylitis (sausage digit), a diffuse swelling of a solitary finger or toe, is a distinctive feature of Reiter's arthritis and psoriatic arthritis. Tendonitis and fasciitis are common. Spinal pain and low back pain are common. Conjunctivitis, urethritis, diarrhea, and skin lesions are also associated with Reiter's syndrome. Up to 75% of patients are HLA-B27 positive. Microorganisms which can trigger Reiter's syndrome include Shigella spp., Salmonella spp., Yersinia spp., Campylobacter jejuni, and Chlamydia trachomatis. Most patients are younger males. Gout (choice A) usually presents as an explosive attack of acute, very painful, monarticular inflammatory arthritis. Hyperuricemia is the cardinal feature and prerequisite for gout. The first metatarsophalangeal joint is involved in over 50% of first attacks. Lyme disease (choice B), caused by Borrelia burgdorferi, presents with a red macule or papule at the site of the tick bite. This lesion, called erythema chronicum migrans, slowly expands to form a large annular lesion with a red border and central clearing. The lesion is warm, but usually not painful. The patient also has severe headache, stiff neck, chills, arthralgias, and profound malaise and fatigue. Untreated infection is associated with development of arthritis. The large joints (e.g., knees) are usually involved with the arthritis lasting for weeks to months. Rheumatoid arthritis (choice D) begins insidiously with fatigue, anorexia, generalized weakness, and vague musculoskeletal symptoms leading up to the appearance of synovitis. Pain in the affected joints, aggravated by movement, is the most common manifestation of established rheumatoid arthritis. Generalized stiffness is frequent and is usually greatest after periods of inactivity. Morning stiffness of greater than 1 hour in duration is very characteristic. Rheumatoid arthritis is more common in females. The metacarpophalangeal and proximal interphalangeal joints of the hands are characteristically involved. Septic arthritis (choice E) is caused by a variety of microorganisms, including Neisseria gonorrhoeae and Staphylococcus aureus. Hematogenous spread is the most common route in all age groups. 90% of patients present with involvement of a single joint, usually the knee. The usual presentation is moderate-to-severe pain, effusion, muscle spasm, and decreased range of motion. Peripheral leukocytosis and a left shift are common. Disseminated gonococcal infections present as fever, chills, rash, and articular symptoms. Papules progressing to hemorrhagic pustules develop on the trunk and extensor surfaces of the distal extremities. Migratory arthritis and tenosynovitis of multiple joints is common.Rate this question:
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- 16.
A 37-year-old woman who was diagnosed with AIDS 3 years earlier is unable to work, is physically debilitated, and requests her physician to provide her with medications with which to take her own life. The most common emotional disorder that results in such requests by patients is
- A.
Bipolar I disorder, manic type
- B.
Borderline personality disorder
- C.
Factitious disorder
- D.
Major depressive disorder
- E.
Schizophrenic disorder
Correct Answer
D. Major depressive disorderExplanation
Many people who request physician-assisted suicide have one of two conditions present: either a poorly controlled painful condition or
severe depression. If the painful condition is adequately treated or the depression is brought under good medical control, the request for physician assistance in terminating the situation is typically withdrawn. It is important to note that bringing these conditions under control requires the intervention of caregivers who are specifically trained in the management of these two conditions; primary care physicians usually are not adequately trained to address these difficult presentations. While patients who are diagnosed as bipolar disorder (choice A), borderline personality disorder (choice B), and schizophrenic disorder (choice E) often make suicide attempts (and frequently complete those attempts), they do not generally ask their physician for assistance in the suicide. Persons with factitious disorder (choice C) are seeking primary gain, often for dependency needs, and are seeking to enter the "sick role" not the "dead role."Rate this question:
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- 17.
A 25-year-old man presents with a chief complaint of persistent, high-pitched ringing noises in his ears. Questioning reveals that he has also been losing his balance lately. CT of the head demonstrates bilateral tumors involving the vestibulocochlear nerve. Which of the following chromosomes contains the tumor suppressor gene most likely to be involved in this case?
- A.
5q
- B.
13q
- C.
17q
- D.
18q
- E.
22q
Correct Answer
E. 22qExplanation
The patient has bilateral acoustic neuromas, probably due to neurofibromatosis type II (over 90% of patients with NF-2 develop bilateral acoustic neuromas). This condition is a associated with the NF-2, gene, located on 22q (note all the 2's). Patients often develop meningiomas, gliomas, and schwannomas of cranial and spinal nerves. 5q (choice A) contains the APC tumor suppressor gene, which is associated with familial and sporadic colorectal cancers. 13q (choice B) contains the Rb tumor suppressor gene, which is associated with retinoblastoma and osteosarcoma. 17q (choice C) contains both the NF-1 tumor suppressor gene, which is associated with neurofibromatosis type I, and the p53 tumor suppressor gene, associated with many human cancers. 18q (choice D) contains both the DCC gene, which is associated with colon and gastric carcinomas and the DPC gene, associated with pancreatic cancer.Rate this question:
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- 18.
An autopsy is performed on a man who suddenly began vomiting voluminous quantities of blood and exsanguinated. Which of the following organisms is most likely implicated in the pathogenesis of this disease?
- A.
Cryptosporidium parvum
- B.
Entamoeba histolytica
- C.
Escherichia coli
- D.
Helicobacter pylori
- E.
Mycobacterium tuberculosis
Correct Answer
D. Helicobacter pyloriExplanation
Perforation of a peptic ulcer is potentially fatal, because of either peritonitis with sepsis or sudden exsanguination (if the perforation damages one of the many arteries of the stomach). Peptic ulcer disease, gastritis, and possibly gastric carcinoma and gastric lymphoma have been strongly associated with Helicobacter pylori colonization of the mucus layer covering the gastric mucosa. Colonization is associated with destruction of the mucus layer, thereby destroying its protective function. Cryptosporidium parvum (choice A) causes diarrhea that is severe in immunocompromised patients. Entamoeba histolytica (choice B) produces dysentery-like symptoms or can cause liver abscess. Escherichia coli (choice C) causes a variety of diarrheal diseases and can infect the bladder and soft tissues. Mycobacterium tuberculosis (choice E) causes tuberculosis, characterized by granuloma formation, especially in the lungs.Rate this question:
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- 19.
During embryological development, hematopoiesis occurs in different organs at different times. Which of the following are the correct organs, in the correct sequence, at which hematopoiesis occurs embryologically?
- A.
Amnion, yolk sac, placenta, bone marrow
- B.
Placenta, liver and spleen, yolk sac, bone marrow
- C.
Placenta, spleen and lymphatic organs, bone marrow
- D.
Yolk sac, bone marrow, liver and spleen
- E.
Yolk sac, liver, spleen and lymphatic organs, bone marrow
Correct Answer
E. Yolk sac, liver, spleen and lymphatic organs, bone marrowExplanation
By the third week of development, hematopoiesis begins in the blood islands of the yolk sac. Beginning at 1 month of age and continuing until 7 months of age, blood elements are also formed in the liver. Hematopoiesis occurs in the spleen and lymphatic organs between 2 and 4 months, and in the bone marrow after 4 months.Rate this question:
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- 20.
A 27-year-old male is brought into the emergency room by the police, who found him walking aimlessly, shouting the names of former Presidents. Urine toxicology is negative, and the man appears to be oriented with respect to person, place, and time. He has had five similar admissions over the past year. Attempts to interview the patient are fruitless, as he seems easily derailed from his train of thought. A phone call to a friend listed in the chart provides the additional information that the man is homeless, and unable to care for himself. This patient is exhibiting the signs and symptoms of
- A.
Schizoaffective disorder
- B.
Schizoid personality disorder
- C.
Schizophrenia
- D.
Schizophreniform disorder
- E.
Schizotypal personality disorder
Correct Answer
C. SchizophreniaExplanation
The patient is suffering from schizophrenia. The key to the diagnosis of psychosis is that there has been a marked decline in the level of functioning (i.e., the man is homeless and cannot care for himself). Although hallucinations or delusions are not mentioned in the case history, the presence of disorganized speech, grossly disorganized behavior, and the duration of symptoms (longer than six months) suggest a diagnosis of schizophrenia. In schizoaffective disorder (choice A), alterations in mood are present during a substantial portion of the illness. Although schizoid personality disorder (choice B) produces detachment from social relationships and is characterized by restriction of emotional expression, it is not accompanied by a marked decline in occupational functioning. Schizophreniform disorder (choice D) is characterized by schizophrenic-like symptoms, but the duration of symptoms is, by definition, less than six months. Schizotypal personality disorder (choice E) is characterized by eccentricities of behavior, odd beliefs or magical thinking, and difficulties with social and interpersonal relationships. Unlike schizophrenia, schizotypal personality disorder is not characterized by a formal thought disorder.Rate this question:
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- 21.
Molecular genetic studies are performed on a family with known familial hypercholesterolemia. In this particular family, the defect in the LDL receptor gene involves a messenger mutation near the 11th exon, in the region of homology with epidermal growth factor receptor precursor. A defect at this site would be most likely to produce which of the following effects?
- A.
Decreased transcription of LDL receptor gene
- B.
Poor internalization of LDL bound to LDL receptor
- C.
Poor retention of the LDL receptor in the membrane
- D.
Reduced binding of LDL
- E.
Trapping of the LDL receptor in the endoplasmic reticulum
Correct Answer
E. Trapping of the LDL receptor in the endoplasmic reticulumExplanation
Familial hypercholesterolemia, which is due to defective function of the LDL receptor, is an area of intense research. The molecular basis of LDL receptor abnormalities is becoming better understood, and more than 200 mutations in the gene for the LDL receptor have been identified. The gene has 5 general domains and 18 exons. Defects near exons 7 to 14 (including this case) are in the region of homology with epidermal growth factor receptor precursor. This region of the molecule is needed for dissociation of LDL from the receptor in the endosome. Receptors with a defect in this area (sometimes called class II mutations) also have trouble being initially transported to the Golgi complex (transport-deficiency alleles) and become trapped in endoplasmic reticulum. Decreased transcription of the LDL receptor gene (choice A) is considered a class I mutation and involves the signal sequence domain near exon 1. Poor internalization of LDL bound to LDL receptor (choice B) is considered a class IV mutation. Such mutations are associated with the membrane-spanning/cytoplasmic domain, specifically near exon 18.Poor retention of the LDL receptor in the membrane (choice C) is considered a class IV mutation and is associated with the membrane-spanning/cytoplasmic domain, specifically near exons 2-6. Reduced binding of LDL (choice D) is considered a class III mutation and involves the LDL binding domain near exons 2-6.Rate this question:
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- 22.
A 27-year-old woman is giving birth. During the birth, the placental membranes tear and amniotic fluid is expressed into a lacerated cervical vein. Which of the following is the woman most likely to experience immediately following this event?
- A.
Hemiplegia
- B.
Placental abruption
- C.
Renal failure
- D.
Respiratory distress
- E.
Splinter hemorrhages
Correct Answer
D. Respiratory distressExplanation
Respiratory distress immediately follows amniotic fluid embolism as the emboli consisting of squamous cells, lanugo, and mucus deposit in the pulmonary microcirculation, producing numerous tiny pulmonary infarcts. The dramatic respiratory distress may also reflect the action of prostaglandins and other bioactive compounds present in high concentrations in the amniotic fluid embolus. Hemiplegia (choice A) would reflect an ischemic injury to one hemisphere of the cerebrum or the brainstem. A venous embolus would not produce such an insult. Placental abruption (choice B) is partial, premature separation of the placental disc from the endometrium. Although abruption may occur in this setting, it is not a result of an amniotic fluid embolism. There are numerous causes of renal failure (choice C); the most likely ones in the peripartum interval include eclampsia, hypovolemic shock, and ascending infections. Amniotic fluid embolism would be expected to produce severe dyspnea well before shock and renal failure might arise. Splinter hemorrhages (choice E) are small hemorrhages seen on toes and fingers due to a shower of microemboli arising in the arterial circulation. Amniotic fluid emboli arise in the veins and deposit in the lungs.Rate this question:
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- 23.
A 30-year-old pregnant woman complains to her physician of feeling very tired during her pregnancy. A complete blood count with differential reveals a hematocrit of 30%, with hypersegmented neutrophils and large, hypochromic red cells. Deficiency of which of the following would be most likely to produce these findings?
- A.
Ascorbic acid
- B.
Calcium
- C.
Copper
- D.
Folate
- E.
Iron
Correct Answer
D. FolateExplanation
The patient has a megaloblastic anemia, which can be due to deficiency of folate or B12. Pregnancy increases the need for folate and other nutrients used by both baby and mother, and may "unmask" a borderline dietary deficiency. For this reason, most obstetricians recommend vitamin supplements for pregnant women. Ascorbic acid (choice A) is vitamin C, and its deficiency predisposes for capillary fragility and oral lesions. Calcium deficiency (choice B) predisposes for osteoporosis/osteopenia. Copper deficiency (choice C) is rare; when it occurs, it may cause a hypochromic anemia, neutropenia, osteoporosis, or hypotonia. Iron deficiency (choice E) causes a microcytic, hypochromic anemia, with reduced mental and physical performance.Rate this question:
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- 24.
An otherwise healthy 3-year-old child is brought to the pediatrician with umbilicated, flesh-colored papules on his trunk. This condition is related to infection with which of the following viruses?
- A.
Cytomegalovirus
- B.
Herpesvirus 6
- C.
Parvovirus
- D.
Poxvirus
- E.
Variola
Correct Answer
D. PoxvirusExplanation
The lesions are characteristic of molluscum contagiosum, which is a typically benign and self-limited condition caused by a poxvirus. The disease can be transmitted either venereally or through non-venereal contact. The other viruses listed do not cause similar skin lesions. Patients with advanced HIV infection may develop a severe, generalized, and persistent eruption, often involving the face and upper body. Cytomegalovirus (choice A) causes congenital infections and disseminated infections in immunosuppressed patients. Herpesvirus 6 (choice B)causes roseola (exanthem subitum). Parvovirus (choice C) causes aplastic crises in patients with hemolytic anemia. Variola (choice E) is the smallpox virus.Rate this question:
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- 25.
Which of the following renal structures is most medially located?
- A.
Major calyx
- B.
Minor calyx
- C.
Renal cortex
- D.
Renal pelvis
- E.
Renal pyramid
Correct Answer
D. Renal pelvisExplanation
This is a relatively simple question that requires you to visualize the relationship among the key parts of the kidney and to identify the one that lies most medially. If you think about it for a second, since the kidneys ultimately drain into the ureter at their medial poles, you are looking for the structure that is closest to the ureter. The correct answer is the renal pelvis. The renal pelvis is the dilated upper portion of the ureter that receives the major calyces. In terms of the other answer choices, the order from most lateral to most medial is: renal cortex (choice C), renal pyramid (choice E), minor calyx (choice B), major calyx (choice A), and then the renal pelvis (choice D).Rate this question:
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- 26.
A 48-year-old female is being treated for breast carcinoma. Over the past few days, she has been complaining of dysuria and frequency. Laboratory examination revealed the presence of microscopic hematuria. The next day the patient developed gross hematuria. Which of the following agents most likely caused the development of these signs and symptoms?
- A.
Cyclophosphamide
- B.
Mitomycin
- C.
Paclitaxel
- D.
Tamoxifen
- E.
Vincristine
Correct Answer
A. CyclophosphamideExplanation
Cyclophosphamide is metabolized to acrolein, which is excreted in the urine. If the patient's urine is concentrated, the toxic metabolite may cause severe bladder damage. Early symptoms of bladder toxicity include dysuria and frequency. This can be distinguished from a urinary tract infection, since there is no bacteriuria with cyclophosphamide-induced bladder toxicity. However, microscopic hematuria is often present on urinalysis. In severe hemorrhagic cystitis, large segments of the bladder mucosa may be shed which can lead to prolonged, gross hematuria. The incidence of cyclophosphamide-induced hemorrhagic cystitis can be decreased by ensuring that the patient maintains a high fluid intake. Cyclophosphamide is an alkylating agent used in the treatment of breast carcinoma, malignant lymphoma, multiple myeloma, and adenocarcinoma of the ovary, as well as various other forms of cancer. The major toxic reactions commonly seen with this agent include mucositis, nausea, hepatotoxicity, sterile hemorrhagic and non-hemorrhagic cystitis, leukopenia, neutropenia, and interstitial pulmonary fibrosis. Mitomycin (choice B) is an antibiotic antineoplastic agent used in the treatment of breast carcinoma, adenocarcinoma of the pancreas and stomach, as well as various other forms of cancer. The major toxic reactions commonly seen with this agent include bone marrow depression, nausea, hepatotoxicity, acute bronchospasm, thrombocytopenia, and interstitial pneumonitis. Paclitaxel (choice C) is an antineoplastic agent primarily used in the treatment of ovarian and breast cancer. The major toxic reactions commonly seen with this agent include bone marrow depression, nausea, hepatotoxicity, bronchospasm, thrombocytopenia, and neutropenia. Tamoxifen (choice D) is an antineoplastic hormone primarily used in the palliative treatment of estrogen-receptor positive breast cancer patients. The major toxic reactions commonly seen with this agent include depression, dizziness, thrombosis, mild leukopenia or thrombocytopenia. Vincristine (choice E) is a mitotic inhibitor antineoplastic agent used in the treatment of breast cancer, Hodgkin'sdisease, non-Hodgkin's lymphoma, advanced testicular cancer and various other types of cancer. The major toxic reactions commonly seen with this agent include mental depression, hemorrhagic enterocolitis, bone marrow depression, nausea, thrombocytopenia, and leukopeniaRate this question:
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- 27.
A child who has had abnormal development of the membranous bones has a broad skull with associated facial and dental anomalies. Which other bones are most likely to also be affected?
- A.
Clavicles
- B.
Femurs
- C.
Metatarsals
- D.
Phalanges
- E.
Tibias
Correct Answer
A. ClaviclesExplanation
In a syndrome called cleidocranial dysostosis, absence of part of the clavicles accompanies a broad skull, and facial and dental anomalies. Note that you could also have answered this question by noting that of the bones listed, only the clavicles form by intramembranous ossification. The femurs (choice B), metatarsals (choice C), phalanges (choice D), and tibias (choice E) are cartilaginous (formed by endochondral ossification) rather than membranous bones.Rate this question:
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- 28.
A 3-year-old child is referred to a major medical center because of an abdominal mass arising from his right adrenal gland. Biopsy of the lesion demonstrates sheets of small cells with hyperchromatic nuclei containing occasional pseudorosettes composed of circles of tumor cells with central young nerve fibers arising from the tumor cells. Which of the following oncogenes is associated with this patient's tumor?
- A.
Erb-B2
- B.
C-myc
- C.
L-myc
- D.
N-myc
- E.
Ret
Correct Answer
D. N-mycExplanation
The tumor is a neuroblastoma, which is one of the principal forms of cancer in children. Neuroblastoma typically occurs before age 5, with many presenting before age 2. Neuroblastoma can arise from neural crest cells throughout the body, but the adrenal medulla is the most common site. Homer-Wright pseudorosettes are circles of tumor cells with central young nerve fibers arising from the tumor cells. The oncogene associated with neuroblastoma is N-myc. erb-B2 (choice A) is associated with breast, ovarian, and gastric carcinomas. c-myc (choice B) is associated with Burkitt's lymphoma. L-myc (choice C) is associated with small cell carcinoma of the lung. ret (choice E) is associated with multiple endocrine neoplasia, types II and III.Rate this question:
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- 29.
A 3-year-old child develops headaches and is brought to the family doctor. Funduscopic examination reveals papilledema; one retina also shows a very vascular tumor. CT of the head demonstrates a cystic tumor of the cerebellum. This child has a high likelihood of later developing which of the following?
- A.
Berry aneurysm of the basilar system
- B.
Bilateral renal cell carcinoma
- C.
Cancer of a peripheral nerve
- D.
Choreiform movements related to decreased GABA and acetylcholine
- E.
Serum cholesterol of greater than 700 mg/dL
Correct Answer
B. Bilateral renal cell carcinomaExplanation
The disease is von Hippel-Landau disease, which is associated with a deletion involving the VHL gene on chromosome 3 (3p). Affected individuals develop vascular tumors (hemangioblastomas) of the retina, cerebellum, and/or medulla. Roughly half of the affected individuals later develop multiple, bilateral renal cell carcinomas. Berry aneurysms (choice A) are unrelated to hemangioblastomas, but are instead associated with adult polycystic disease. Peripheral nerve cancers (choice C) are a feature of von Recklinghausen's disease (neurofibromatosis type I). Choreiform movements, related to decreased GABA and acetylcholine (choice D), are a feature of Huntington's disease. Extremely high serum cholesterol (choice E) suggests the homozygous form of familial hypercholesterolemia.Rate this question:
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- 30.
Administration of an experimental drug that acts on PNS myelin is shown to increase the space constant of an axon in a peripheral nerve. Action potentials traveling down the axon would be predicted to be
- A.
Faster
- B.
Larger
- C.
Slower
- D.
Smaller
- E.
Unchanged
Correct Answer
A. FasterExplanation
The space constant of an axon reflects the amount of passive or electrotonic spread of current within an axon. The larger the space constant, the further the current can spread, allowing action potentials to propagate faster. This is why myelin increases the conduction velocity of action potentials down an axon. Conversely, demyelination decreases the space constant and slows action potential conduction.Rate this question:
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- 31.
A 26-year-old man presents to his physician with a chronic cough. The man is a smoker, and states that he also gets frequent headaches and aches in his legs when he exercises. Chest x-ray demonstrates notching of his ribs. Which of the following undiagnosed congenital defects may be responsible for these findings?
- A.
Coarctation of the aorta
- B.
Eisenmenger's syndrome
- C.
Tetralogy of Fallot
- D.
Transposition of great vessels
- E.
Ventricular septal defect
Correct Answer
A. Coarctation of the aortaExplanation
Coarctation of the aorta occurs in two patterns. In the infantile type, the stenosis is proximal to the insertion of the ductus arteriosus (preductal); this pattern is associated with Turner's syndrome. In the adult form, the stenosis is distal to the ductus arteriosus (postductal) and is associated with notching of the ribs (secondary to continued pressure from the aorta on them), hypertension in the upper extremities, and weak pulses in the lower extremities. Headache, cold extremities, and lower extremity claudication with exercise are typical if the patient is symptomatic (many adults with mild distal coarctation may remain asymptomatic for years). Upper extremity hypertension with weak pulses in the lower extremities, and a midsystolic (or continuous) murmur over the chest or back may be the only obvious signs in some. Note that the chronic cough is probably related to the man's smoking, and is not caused by the coarctation. Eisenmenger's syndrome (choice B) is a shift from a left-to-right shunt to a right-to-left shunt secondary to pulmonary hypertension. Tetralogy of Fallot (choice C) and transposition of great arteries (choice D) cause cyanosis and are usually diagnosed in infancy. Ventricular septal defect (choice E) might remain undiagnosed until adulthood, but would not cause notching of the ribs.Rate this question:
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- 32.
A 36-year-old Asian male complains of difficulty swallowing. Esophagoscopy reveals a polypoid mass that is subsequently biopsied. In addition to tumor cells, the esophageal biopsy show normal smooth muscle and striated muscle in the same section. Which portion of the esophagus was the source of this biopsy?
- A.
Lower esophageal sphincter
- B.
Lower third of the esophagus
- C.
Middle third of the esophagus
- D.
Upper esophageal sphincter
- E.
Upper third of the esophagus
Correct Answer
C. Middle third of the esophagusExplanation
The muscularis of the upper third of the esophagus (choice E) is composed entirely of striated muscle. The middle third (choice C) contains both striated and smooth muscle. The lower third (choice B) and lower esophageal sphincter (choice A) contain only smooth muscle. There is no such thing as the upper esophageal sphincter (choice D).Rate this question:
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- 33.
A 25-year-old woman with sickle cell anemia complains of steady pain in her right upper quadrant with radiation to the right shoulder, especially after large or fatty meals. Her physician diagnoses gallstones. Of which of the following compounds are these stones most likely composed?
- A.
Calcium bilirubinate
- B.
Calcium oxalate
- C.
Cholesterol
- D.
Cholesterol and calcium bilirubinate
- E.
Cystine
Correct Answer
A. Calcium bilirubinateExplanation
Bilirubin is a degradative product of hemoglobin metabolism. Bilirubin (pigment) stones are specifically associated with excessive bilirubin production in hemolytic anemias, including sickle cell anemia. Bilirubin stones can also be seen in hepatic cirrhosis and liver fluke infestation. Calcium oxalate stones (choice B) and cystine stones (choice E) are found in the kidney, rather than the gallbladder. Pure cholesterol stones (choice C) are less common than mixed gallstones, but have the same risk factors, including obesity and multiple pregnancies. Mixed stones (choice D) are the common "garden variety" gallstones, found especially in obese, middle aged patients, with a female predominanceRate this question:
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- 34.
A 54-year-old alcoholic presents with complaints of tremors and muscle twitching. Physical examination reveals the presence of Trousseau's sign. Laboratory data show that serum magnesium is < 1 mEq/L (normal, 1.4 - 2.2 mEq/L). Which of the following findings would be most consistent with this information?
- A.
Decreased serum calcium
- B.
Decreased serum phosphate
- C.
Increased bone density
- D.
Increased plasma parathyroid hormone concentration
- E.
Increased urinary cAMP concentration
Correct Answer
A. Decreased serum calciumExplanation
Malnutrition associated with chronic alcoholism can lead to a severe magnesium deficiency. The effect of low serum magnesium on parathyroid hormone secretion (PTH) depends on severity and duration. An acute decrease in serum magnesium will increase PTH secretion, while a prolonged severe deficiency results in
decreased PTH secretion. There is also evidence that the action of PTH is decreased with chronic magnesium deficiency. Hence, this patient is suffering from "functional" hypoparathyroidism. The low serum calcium can produce weakness, tremors, muscle fasciculations, and seizures. A positive Trousseau's sign indicates the presence of latent tetany. It is observed by inflating a blood pressure cuff above systolic blood pressure for at least 2 minutes. A positive reaction consists of the development of carpal spasm, with relaxation occurring within seconds after deflating the cuff. In patients with magnesium deficiency, magnesium administration will produce a prompt rise in plasma PTH with subsequent restoration of serum calcium concentration to normal. With functional hypoparathyroidism bone density would be decreased (not increased, choice C). The combination of decreased PTH secretion (not increased, choice D) and decreased effectiveness of PTH produce hypocalcemia and hyperphosphatemia (not hypophosphatemia, choice B). Urinary cAMP would probably be decreased (not increased, choice E), given the low PTH.Rate this question:
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- 35.
A young boy presents with failure to thrive. Biochemical analysis of a duodenal aspirate after a meal reveals a deficiency of enteropeptidase (enterokinase). The levels of which of the following digestive enzymes would be affected?
- A.
Amylase
- B.
Colipase
- C.
Lactase
- D.
Pepsin
- E.
Trypsin
Correct Answer
E. TrypsinExplanation
Enteropeptidase, formerly called enterokinase, activates trypsinogen by limited proteolytic digestion to give trypsin. Trypsin is itself capable of activating trypsinogen, which produces a positive feedback effect. Trypsin also activates chymotrypsinogen (and several other proteolytic enzymes), so deficiency of enteropeptidase results in a severe deficiency of enzymes that digest protein. Amylase (choice A) aids in the breakdown of starches to oligosaccharides, maltose, and maltotriose. Colipase (choice B), along with other lipases, functions to digest fats. Lactase (choice C) is a brush-border disaccharidase that hydrolyzes the bond between galactose and glucose in lactose. Pepsin (choice D) is a proteolytic enzyme secreted in an inactive form (pepsinogen) by the chief cells of the stomach. Pepsinogen is activated by stomach acid, and so is not dependent on enteropeptidase. Pepsin alone will not replace the activities of other proteolytic enzymes, partly because food does not remain in the stomach for an extended period of time.Rate this question:
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- 36.
A Guatemalan child with a history of meconium ileus is brought to a clinic because of a chronic cough. The mother notes a history of respiratory tract infections and bulky, foul-smelling stools. After assessment of the respiratory tract illness, the physician should also look for signs of
- A.
Cystinuria
- B.
Hypoglycemia
- C.
Iron deficiency anemia
- D.
Sphingomyelin accumulation
- E.
Vitamin A deficiency
Correct Answer
E. Vitamin A deficiencyExplanation
The child is likely suffering from cystic fibrosis. In this disorder, an abnormality of chloride channels causes all exocrine secretions to be much thicker, and more viscous than normal. Pancreatic secretion of digestive enzymes is often severely impaired, with consequent steatorrhea and deficiency of fat-soluble vitamins, including vitamin A. Cystinuria (choice A) is a relatively common disorder in which a defective transporter for dibasic amino acids (cystine, ornithine, lysine, arginine; COLA) leads to saturation of the urine with cystine, which is not very soluble in urine, and precipitates out to form stones. Hypoglycemia (choice B) is not a prominent feature of children with cystic fibrosis who are on a normal diet. Hyperglycemia may occur late in the course of the disease. Iron deficiency anemia (choice C) is not found with any regularity in children with cystic fibrosis. Sphingomyelin accumulation (choice D) is generally associated with deficiency of sphingomyelinase, as seen in Niemann-Pick disease.Rate this question:
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- 37.
A 48-year-old white female secretary presents with progressive difficulty typing over the past month. She also notes that her hands begin to feel numb and weak after typing for long periods of time. Upon testing, which of the following deficits would be predicted?
- A.
Difficulty in abducting the fifth finger
- B.
Difficulty in adducting the thumb
- C.
Difficulty in flexing digits two and three at the metacarpophalangeal joints
- D.
Loss of sensation over the lateral half of the dorsum of the hand
- E.
Loss of sensation over the lateral half of the palm
- F.
Loss of sensation over the medial half of the dorsum of the hand
- G.
Loss of sensation over the medial half of the palm
Correct Answer
C. Difficulty in flexing digits two and three at the metacarpophalangeal jointsExplanation
This is a classic presentation of a patient with carpal tunnel syndrome, which typically affects females between the ages of 40 and 60 who chronically perform repetitive tasks that involve movement of the structures that pass through the carpal tunnel. One important structure that passes through the carpal tunnel is the median nerve. Patients often note a tingling, a loss of sensation, or diminished sensation in the digits. There is also often a loss of coordination and strength in the thumb, because the median nerve also sends fibers to the abductor pollicis brevis, flexor pollicis brevis, and the opponens pollicis. A final function of the median nerve distal to the carpal tunnel is control of the first and second lumbricals which function to flex digits two and three at the metacarpophalangeal joints and extend interphalangeal joints of the same digits. Abduction of the fifth digit (choice A) is a function controlled by the ulnar nerve, which does not pass through the carpal tunnel. Adduction of the thumb (choice B) is a function of the adductor pollicis, which is the only short thumb muscle that is not innervated by the median nerve, but rather by the deep branch of the ulnar nerve. Sensation of the lateral half of the dorsum of the hand (choice D) is mediated by the radial nerve, which also does not pass through the carpal tunnel. Sensation over the lateral aspect of the palm (choice E) is mediated by the median nerve, however the branch
innervating the palm (palmar cutaneous branch of the median nerve) passes superficial to the carpal tunnel. Sensation over the medial aspect of the dorsum of the hand (choice F) is mediated by the ulnar nerve. Sensation over the medial aspect of the palm (choice G) is mediated by the ulnar nerve.Rate this question:
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- 38.
The smooth part of the right atrium derives from which of the following embryonic structures?
- A.
Bulbus cordis
- B.
Primitive atrium
- C.
Primitive ventricle
- D.
Sinus venosus
- E.
Truncus arteriosus
Correct Answer
D. Sinus venosusExplanation
The smooth part of the right atrium (the sinus venarum) is derived from the sinus venosus. The coronary sinus and the oblique vein of the left atrium also derive from the sinus venosus. The bulbus cordis (choice A) gives rise to the smooth part of the right ventricle (conus arteriosus) and the smooth part of the left ventricle (aortic vestibule). The primitive atrium (choice B) gives rise to the trabeculated part of the right and left atria. The primitive ventricle (choice C) gives rise to the trabeculated part of the right and left ventricles. The truncus arteriosus (choice E) gives rise to the proximal part of the aorta and the proximal part of the pulmonary artery.Rate this question:
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- 39.
A 66-year-old male presents with chronic fatigue. On examination, the patient is noted to have lymphadenopathy and an enlarged liver and spleen. Laboratory examination reveals a white blood cell count of 25,000/mL with 93% lymphocytes; the lymphocytes appear small and mature. Both the hematocrit and platelet counts are within normal limits; however, hypogammaglobulinemia is also noted. Which of the following agents is indicated for treatment of this patient's condition?
- A.
Chlorambucil
- B.
Cisplatin
- C.
Dacarbazine
- D.
Tamoxifen
- E.
Vinblastine
Correct Answer
A. ChlorambucilExplanation
Chronic lymphocytic leukemia (CLL) is typically a disease of the elderly, with 90% of cases occurring after the age of 50; the median age is 65. Patients will typically present with a complaint of chronic fatigue and/or lymphadenopathy. Approximately 50% of all patients with CLL present with an enlarged liver and/or spleen. CLL typically pursues an indolent course but can occasionally present as a rapidly progressive disease. The hallmark of CLL is the isolated lymphocytosis in which the white blood cell count is usually greater than 20,000/mL and between 75% and 98% of the circulating cells are small "mature" lymphocytes. Chlorambucil is classified as a nitrogen mustard, a subcategory of the alkylating agents. It is primarily used to treat chronic lymphocytic leukemia and ovarian carcinoma; it can also be used to treat Hodgkin's disease and various other lymphomas. Cisplatin (choice B) is an alkylating agent indicated for the treatment of metastatic testicular and ovarian tumors in combination with other agents. Dacarbazine (choice C) is a cytotoxic agent with alkylating properties. It is used as a single agent or in combination with other antineoplastics in the treatment of metastatic malignant melanoma, refractory Hodgkin's disease, and various sarcomas. Tamoxifen (choice D) is an antiestrogen hormone used in the palliative treatment of breast cancer in patients with estrogen-receptor-positive breast cancer. Vinblastine (choice E) is a mitotic inhibitor antineoplastic agent indicated for the treatment of Hodgkin's disease and non-Hodgkin's lymphomas, choriocarcinoma, lymphosarcoma, and neuroblastoma, as well as various other types of cancer.Rate this question:
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- 40.
A patient who has suffered severe chest trauma in an automobile accident is found to have fluid in the right pleural space. A thoracentesis reveals the presence of chylous fluid in the pleural space, suggesting a rupture of the thoracic duct. In which regions of the thorax is the thoracic duct found?
- A.
Anterior and middle mediastinum
- B.
Anterior and superior mediastinum
- C.
Middle and posterior mediastinum
- D.
Middle and superior mediastinum
- E.
Posterior and superior mediastinum
Correct Answer
E. Posterior and superior mediastinumExplanation
The mediastinum is divided into four regions. The region above the manubriosternal junction (level of fourth thoracic vertebra) is the superior mediastinum. The region below the manubriosternal junction is divided into the anterior mediastinum (anterior to the pericardium), the middle mediastinum (within the pericardium), and the posterior mediastinum (posterior to the pericardium). The thoracic duct enters the thorax through the aortic hiatus of the diaphragm. At this point it lies in the posterior mediastinum, the region posterior to the pericardium. As it ascends through the thorax and passes the level of the fourth thoracic vertebra, it enters the superior mediastinum. The anterior mediastinum (choices A and B) contains the thymus and fatty connective tissue. The middle mediastinum (choices A, C, and D) contains the heart and the roots of the great vessels. In addition to the thoracic duct, the superior mediastinum (choices B, D, and E) contains the ascending aorta, aortic arch, branches of the aortic arch, descending aorta, superior vena cava, brachiocephalic veins, thymus, trachea and esophagus. In addition to the thoracic duct, the posterior mediastinum (choices C and E) contains the descending aorta, azygos vein, hemiazygos vein and the esophagusRate this question:
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- 41.
A 15-year-old boy is evaluated by a clinician for failure to develop norma l male secondary sexual characteristics. Physical examination reveals small testes, a small penis, and gynecomastia. The boy has had some difficulties in school, and the parents say that the school psychometrist said he had an IQ of 90. This patient's condition is most likely to be related to which of the following?
- A.
Deletion
- B.
Nondisjunction of an autosomal chromosome
- C.
Nondisjunction of a sex chromosome
- D.
Non-Robertsonian translocation
- E.
Robertsonian translocation
Correct Answer
C. Nondisjunction of a sex chromosomeExplanation
The boy probably has Klinefelter's syndrome (47, XXY), which has the typical presentation described in the question. The condition arises as a result of failure of separation (nondisjunction) of the sex chromosomes, and can be related to either paternal nondisjunction (slightly more common) or maternal nondisjunction. Deletions (choice A) are a common form of genetic disease and contribute to many genetic recessive diseases. Examples of nondisjunction of autosomes (choice B) include trisomies such as most cases of Down's syndrome (trisomy 21), Edwards' syndrome (trisomy 18), and Patau syndrome (trisomy 13). There are two types of translocations: non-Robertsonian (choice D) and Robertsonian (choice E). Non-Robertsonian (reciprocal) translocations result when two non-homologous chromosomes exchange genetic material. Robertsonian translocations are a special type of translocation that involve exchange of genetic material from the long arms of one acrocentric chromosome to the long arms of another acrocentric chromosome, with fusion of the centromeres. Four percent of cases of Down's syndrome are caused by this mechanism.Rate this question:
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- 42.
Careful testing of the visual fields in a patient complaining of difficulty reading demonstrates a central scotoma involving one visual field. This defect is most likely due to a lesion involving which of the following structures?
- A.
Macula
- B.
Optic chiasm
- C.
Optic radiations in the parietal lobe
- D.
Optic radiations in the temporal lobe
- E.
Optic tract
Correct Answer
C. Optic radiations in the parietal lobeExplanation
The probable location of lesions producing visual defects is a favorite USMLE topic (and is also well worth knowing if you have occasion to work up such a patient). Here is a list that may help you sort through
these problems: Central scotoma ~ macula Ipsilateral blindness ~ optic nerve Bitemporal hemianopia ~ optic chiasm (choice B) Homonymous hemianopia ~ optic tract (choice E) Upper homonymous quadrantanopia ~ temporal optic radiations (choice D) Lower homonymous quadrantanopia ~ parietal optic radiations (choice C) Also, cortical lesions produce defects similar to those of the optic radiations, but may spare the macula.Rate this question:
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- 43.
A 70-year-old woman with a history of multiple small strokes reports to her physician that she has had multiple recent experiences that something or someone seemed very familiar, when in reality they were not familiar to her. This type of experience is called which of the following?
- A.
Anterograde amnesia
- B.
Confabulation
- C.
Deja vu
- D.
Jamais vu
- E.
Retrograde amnesia
Correct Answer
C. Deja vuExplanation
This is deja vu ("seen before"), which is the experience of an event, person, or thing as familiar, even though it has never previously been experienced. Severe cases often accompany an underlying neurologic problem. Anterograde amnesia (choice A) is the inability to learn new facts. Most commonly, it involves both verbal and nonverbal material, but it can involve one or the other. In confabulation (choice B), a patient reports "memories" of events that did not take place at the time in question. In jamais vu (choice D), a patient fails to recognize familiar events that have been encountered before. In retrograde amnesia (choice E), a patient fails to remember facts or events that occurred before the onset of amnesia.Rate this question:
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- 44.
A 33-year-old single mother of two young children visits her physician because of an oral ulcer. A review of systems is significant for fatigue, myalgia, and joint pain. Laboratory results demonstrate leukopenia, and a high-titered antinuclear antibody. A speckled staining pattern due to anti-Sm is seen with immunofluorescence; urinary protein is elevated. Which of the following is the most likely diagnosis?
- A.
Generalized fatigue
- B.
Goodpasture's syndrome
- C.
Mixed connective tissue disease
- D.
Scleroderma
- E.
Systemic lupus erythematosus
Correct Answer
E. Systemic lupus erythematosusExplanation
Systemic lupus erythematosus (SLE) is a prototype connective tissue disease. The diagnosis requires four criteria to be met from a list of eleven possible criteria: malar rash, discoid rash, photosensitivity, oral ulcers, arthritis, serositis, renal disorder, neurologic disorder, hematologic disorder, immunologic disorder, and antinuclear antibody. This patient also has anti-Sm, which is pathognomonic for SLE, but is only found in 30% of the affected patients. Antinuclear antibodies (ANA) are present in 95-100% of cases of SLE; anti-double-stranded DNA is found in 70% of the cases. Generalized fatigue (choice A) due to being a single working mother of two children could well be a possibility, but the presence of the other criteria make SLE more likely. Goodpasture's syndrome (choice B) is characterized by linear disposition of immunoglobulin, and often C3, along the glomerular basement membrane (GBM). Glomerulonephritis, pulmonary hemorrhage, and occasionally idiopathic pulmonary hemosiderosis occur. Mixed connective tissue disease (choice C) is an overlap syndrome characterized by a combination of clinical features similar to those of SLE, scleroderma, polymyositis, and rheumatoid arthritis. These patients generally have a positive ANA in virtually 100% of the cases. High titer anti-ribonucleoprotein (RNP) antibodies may be present, generating a speckled ANA pattern. Anti-RNP is not pathognomonic for mixed connective tissue disease, since it can be found in low titers in 30% of the patients with SLE. Scleroderma (choice D) is characterized by thickening of the skin caused by swelling and thickening of fibrous tissue, with eventual atrophy of the epidermis. ANA are often associated with the disease, but the staining pattern is generally nucleolar.Rate this question:
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- 45.
Researchers are assessing the specificity of a screening procedure for breast cancer in a population of 3000 women whose mothers had the disease. The presence or absence of a malignant condition is established by conventional mammography, which is assumed to be definitive for the purposes of comparison. The following data are collected: Positive Negative Total Cancer 90 10 100 No cancer 360 2540 2900 Total 450 2550 3000 What is the specificity of the test?
- A.
90/100
- B.
90/450
- C.
2540/2550
- D.
2540/2900
- E.
(90+2540)/3000
Correct Answer
D. 2540/2900Explanation
Specificity refers to how well a test identifies persons who do not have the disease in question. In the example, 2900 women do not have breast cancer, and 2540 of these women have a negative test. Specificity is given by (true negatives)/ (true negatives + false positives) = 2540/(2540+360) = 2540/2900. Choice A, 90/100, represents the sensitivity of the test; that is, the proportion of women with the condition who test positive. Choice B, 90/450, gives the predictive value of a positive test. Of the 450 women who tested positive, 90 actually had the condition. Choice C, 2540/2550, gives the predictive value of a negative test. Of the 2550 who tested negative, 2540 did not have cancer. Choice E, (90+2540)/3000, refers to the efficiency of a test; that is, the proportion of all subjects who were correctly classified by the test.Rate this question:
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- 46.
A patient develops fever, shortness of breath, and appears to be quite ill. X-ray demonstrates bilateral interstitial lung infiltrates. Bronchial washings demonstrate small "hat-shape" organisms visible on silver stain within alveoli. Which predisposing condition is most likely to be present in this patient?
- A.
AIDS
- B.
Congestive heart failure
- C.
Pulmonary embolus
- D.
Rheumatoid arthritis
- E.
Systemic lupus erythematosus
Correct Answer
A. AIDSExplanation
The disease is Pneumocystis pneumonia, which is caused by an agent now believed to be a fungus rather than a true bacteria. Pneumocystis carinii pneumonia is seen in immunocompromised patients, particularly in those with AIDS, cancer, and in malnourished children. It can be the AIDS-defining illness. Congestive heart failure (choice B) predisposes the patient to pulmonary edema. Pulmonary embolus (choice C) can cause pulmonary infarction or sudden death. Rheumatoid arthritis (choice D), particularly in miners, can cause formation of lung nodules similar to subcutaneous rheumatoid nodules. Systemic lupus erythematosus (choice E) can cause pleuritis, but is not associated with a significantly increased incidence of pneumonia.Rate this question:
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- 47.
A 35-year-old retarded man with a strong history of mental retardation among male relatives undergoes genetic testing. His lymphocytes are cultured in a medium containing methotrexate and 4% of the metaphase chromosomes in the lymphocytes show a breakpoint at q27.3 on the X chromosome. This man is at increased risk for which of the following cardiovascular disorders?
- A.
Aortic stenosis
- B.
Atrial septal defect
- C.
Mitral valve prolapse
- D.
Tricuspid atresia
- E.
Ventricular septal defect
Correct Answer
C. Mitral valve prolapseExplanation
The disease is Fragile X Syndrome, which is a familial form of mental retardation that is roughly as common as Down's syndrome. The phenotype has a variable expression, but can include large head circumference at birth, perinatal complications (premature birth, asphyxia, seizures), and possibly increased incidence of sudden infant death syndrome. Later, mental retardation, particularly involving language, and symptoms suggestive of attention deficit disorder and/or autism may appear. Features suggestive of connective tissue disorder (lax skin and joints, flat feet, large ears) are common. After puberty, there may be a long narrow face with prominent jaw and nasal bridge. Macro-orchidism is also common after puberty. Mitral valve prolapse and aortic root dilatation, which may appear in late adolescence or
adulthood, are among the most serious complications of this disorder. Aortic regurgitation related to aortic root dilatation, not stenosis (choice A), can be a problem in this population. Common congenital cardiac malformations such as atrial septal defect (choice B) or ventricular septal defect (choice E) are not features of Fragile X syndrome, but can be seen with Down's syndrome.Tricuspid atresia (choice D) is a serious congenital cardiac malformation limiting flow into the right ventricle, but it is not part of Fragile X syndrome.Rate this question:
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- 48.
While lying supine in bed eating, a child aspirates a peanut. Which of the following bronchopulmonary segments would this foreign object mos t likely enter?
- A.
Apical segment of the left upper lobe
- B.
Apical segment of the right upper lobe
- C.
Medial segment of the right middle lobe
- D.
Posterior basal segment of the left lower lobe
- E.
Superior segment of the right lower lobe
Correct Answer
E. Superior segment of the right lower lobeExplanation
Because the right main bronchus is wider and more vertical than the left, foreign objects are more likely to be aspirated into the right main bronchus. The superior segmental bronchus of the lower lobar bronchus is the only segmental bronchus that exits from the posterior wall of the lobar bronchi. Therefore, if a patient is supine at the time of aspiration, the object is most likely to enter the superior segmental bronchus of the lower lobe. None of the segmental bronchi of the left lung (choices A and D) are likely to receive the object because the object is less likely to enter the left main bronchus. The apical segment of the right upper lobe (choice B) is not likely to receive the foreign object because of the sharp angle that the upper lobar bronchus makes with the right main bronchus and the sharp angle that the apical segmental bronchus makes with the lobar bronchus. The medial segmental bronchus of the right middle lobe (choice C) arises from the anterior wall of the right middle lobar bronchus. Therefore, when the patient is supine, the effect of gravity will tend to prevent the object from entering this segmental bronchus.Rate this question:
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- 49.
A 43-year-old man is brought to the general medicine clinic by his wife. She states that his memory has progressively deteriorated over the last several years, and that his personality has been changing. On examination, the physician notes abnormal, writhing movements of the man's limbs and hyperreactive patellar reflexes. An MRI of the head reveals a loss of volume in the neostriatum and cortex. A family history reveals that similar symptoms occurred in several members of the patient's family. Which of the following genetic mechanisms has been implicated in this disorder?
- A.
Expanded trinucleotide tandem repeat
- B.
Genomic imprinting
- C.
Large deletion in one gene
- D.
Single amino acid substitution
- E.
Translocation
Correct Answer
A. Expanded trinucleotide tandem repeatExplanation
The disease described is Huntington's disease, which is now known to be related to an expanded trinucleotide tandem repeat on the short arm of chromosome 4. The number of trinucleotide repeats frequently increases in succeeding generations during the process of spermatogenesis. Prader-Willi and Angelman syndromes are frequently cited examples of genetic diseases involving genomic imprinting (choice B). Duchenne's muscular dystrophy is an example of a disease that is frequently due to a large deletion in a single gene (choice C). Single amino acid substitutions (choice D) are common in recessive diseases such as sickle cell anemia. Translocations (choice E) occur in disorders such as chronic myelogenous leukemia (CML; Philadelphia chromosome) and some cases of Down's syndrome.Rate this question:
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- 50.
During a routine physical examination of a 74-year-old man, a physician palpates a large, pulsating mass in the lower abdomen. To which of the following is this mass most likely etiologically related?
- A.
Atherosclerosis
- B.
Bacterial infection
- C.
Congenital anomaly
- D.
Cystic medial degeneration
- E.
Syphilis
Correct Answer
A. AtherosclerosisExplanation
The mass is an abdominal aortic aneurysm, typically found in older men. Such aneurysms are almost always related to the formation of complicated atherosclerotic plaques in the aorta. Associated coronary artery disease is commonplace. Bacterial infection (choice B) can cause "mycotic" aneurysms; these usually involve smaller vessels. The small berry aneurysms that can involve the circle of Willis are congenital anomalies (choice C). Cystic medial degeneration (choice D) is related to the development of dissecting aneurysms (actually dissecting hematomas). Tertiary syphilis (choice E) typically causes aneurysms of the root and arch of the aorta, rather than the descending aorta.Rate this question:
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