1.
A 46-year-old woman has experienced severe headaches, worsening over the past two months. She has noted difficulty moving her left arm during the past day. On physical examination papilloedema is noted, worse on the right. Through which of the following mechanisms are these findings most likely to be produced?
Correct Answer
E. Oedema around a glioblastoma multiforme
Explanation
The correct answer is "Oedema around a glioblastoma multiforme." Glioblastoma multiforme is a type of brain tumor that can cause increased pressure in the brain, leading to symptoms such as severe headaches and difficulty moving limbs. Papilloedema, which is swelling of the optic disc due to increased intracranial pressure, is also commonly seen in patients with glioblastoma multiforme. The edema around the tumor can compress nearby structures, leading to neurological deficits such as difficulty moving the left arm.
2.
A 78-year-old man died following a vehicle accident. He was a known hypertensive for over 28 years on irregular treatment and was being treated for recent behavioral changes by a psychiatrist. The below image shows his brain removed at autopsy. What is the most likely diagnosis?
Correct Answer
D. Meningioma
Explanation
Note well-demarcated tumor arising from falx cerebri, typical of a meningioma.
3.
A 47-year-old man had an onset of headaches 4 months ago. The headaches are associated with dull pain and seem diffuse, but they are becoming more frequent and prolonged. On physical examination, he has no focal neurologic deficits. His memory is intact. MR imaging reveals moderate hydrocephalus with enlargement of the lateral ventricles. There is a 4 cm homogenous, well-circumscribed mass within the fourth ventricle. Which of the following is the most likely diagnosis?
Correct Answer
B. Ependymoma
Explanation
The patient's presentation of headaches, diffuse dull pain, and increasing frequency and duration, along with the findings of moderate hydrocephalus and enlargement of the lateral ventricles on MR imaging, suggest a mass obstructing the flow of cerebrospinal fluid (CSF). The presence of a well-circumscribed mass within the fourth ventricle points towards ependymoma as the most likely diagnosis. Ependymomas are tumors that arise from the ependymal cells lining the ventricles and can cause obstructive hydrocephalus. The other options, such as astrocytoma, meningioma, metastatic carcinoma, and schwannoma, are less likely based on the given information.
4.
A 68-year-old woman presents to you complaining of headaches and nausea over the last month. CT scan shows a temporal tumor with extensive edema consistent with glioma. Her past medical history is significant for hypertension, gastric ulcers, hysterectomy, and stomach surgery. The below image shows the CT guided biopsy of the mass. What is the most prominent pathological feature?
Correct Answer
B. Necrosis and pseudopalisading
Explanation
The most prominent pathological feature in the CT guided biopsy of the mass is necrosis and pseudopalisading. This is indicated by the presence of areas of necrotic tissue and the formation of palisading cells around the necrotic areas. This finding is consistent with glioma, a type of brain tumor characterized by aggressive growth and necrosis.
5.
A 63-year-old man complains of trouble swallowing and hoarseness. On physical examination, he is noted to have ptosis and a constricted pupil on the left, and a diminished gag reflex. Neurological examination shows decreased pain and temperature sensation on the left side of his face and on the right side of his body. Which of the following vessels is most likely occluded?
Correct Answer
E. Posterior inferior cerebellar artery (PICA)
Explanation
The patient's symptoms, including trouble swallowing, hoarseness, ptosis, constricted pupil, and diminished gag reflex, suggest dysfunction of the cranial nerves and spinal cord. The PICA supplies blood to the medulla, which contains the nuclei of cranial nerves involved in swallowing (CN IX and X) and the spinal trigeminal nucleus, which is responsible for pain and temperature sensation on the face. Therefore, occlusion of the PICA is the most likely cause of the patient's symptoms.
6.
A 3-year-old child is brought to the Emergency Department by her concerned parents. She complains of a sore head. She is lethargic and listless and committed twice. On examination, she has a fever and bilateral papilloedema. Her GCS is 9. What is the most likely cause of her findings?
Correct Answer
D. Otitis media
Explanation
The most likely cause of the child's symptoms and findings is otitis media. Otitis media is an infection and inflammation of the middle ear, which can cause symptoms such as a sore head, lethargy, fever, and vomiting. The bilateral papilloedema suggests increased intracranial pressure, which can occur due to the infection spreading to the brain or causing meningitis. Bacteremia following tooth extraction, bacterial meningitis, lung abscess, and sinusitis are less likely to present with these specific symptoms and findings.
7.
A 25-year-old man presents with bilateral hearing loss. MRI reveals bilateral tumors within the cerebellopontine angles. Surgery is performed, and the tumors are removed. Both are found to be neurilemomas ("schwannoma"). Which of the following is the most likely diagnosis?
Correct Answer
D. Neurofibromatosis type 2
Explanation
The most likely diagnosis in this case is Neurofibromatosis type 2. Neurofibromatosis type 2 is a genetic disorder characterized by the development of bilateral vestibular schwannomas, which are tumors that arise from Schwann cells. These tumors typically occur within the cerebellopontine angles and can lead to bilateral hearing loss, as seen in this patient. Other features of Neurofibromatosis type 2 may include the development of other central nervous system tumors, such as meningiomas or ependymomas.
8.
A 4-year-old boy presents with headaches and vomiting. On examination, he has papilloedema and loss of coordination. Biopsy reveals evidence of both neuronal and glial differentiation. Which of the following is the most likely diagnosis?
Correct Answer
C. Medulloblastoma
Explanation
Medulloblastoma is the most likely diagnosis in this case because it is a highly malignant brain tumor that commonly occurs in children. The symptoms of headaches, vomiting, papilloedema, and loss of coordination are consistent with medulloblastoma. Additionally, the biopsy findings of both neuronal and glial differentiation support this diagnosis. Astrocytoma, glioblastoma multiforme, meningioma, and oligodendroglioma are less likely because they do not typically present with these specific symptoms and biopsy findings in a 4-year-old child.
9.
A 62-year-old chronic smoker presents with persistent headaches. A CT scan of the head demonstrates a 2 cm spherical mass at the junction of the white and grey matter of the lateral aspect of the cerebral hemisphere. Which of the following would most likely produce this lesion?
Correct Answer
E. Metastatic carcinoma
Explanation
Metastatic carcinoma is the most likely cause of the 2 cm spherical mass at the junction of the white and grey matter of the cerebral hemisphere in a chronic smoker. Metastatic carcinoma refers to cancer that has spread from its original site to another part of the body. In this case, the persistent headaches and the location of the mass suggest that the primary cancer has metastasized to the brain. Chronic smoking is a risk factor for developing various types of cancer, including lung cancer, which commonly metastasizes to the brain.
10.
A 34-year-old man with AIDS suddenly falls to the floor and has a tonic-clonic seizure. His concerned friends call paramedics, who take him to the hospital. On arrival at the hospital, he is conscious but confused. Physical examination is remarkable for cachexia and oral thrush. Neurological examination reveals the isolated weakness of lateral gaze on the right. MRI reveals multicentric mass lesions in the brain and meninges. One of the masses is biopsied and appropriate immunohistochemical stains are performed. From which of the following cell types did the masses most likely derive?
Correct Answer
B. B lympHocyte
Explanation
The correct answer is B lymphocyte. The patient's clinical presentation, including cachexia, oral thrush, and neurological findings, is consistent with advanced AIDS. The multicentric mass lesions in the brain and meninges suggest the presence of a primary central nervous system (CNS) lymphoma, which is commonly seen in immunocompromised patients, such as those with AIDS. Immunohistochemical stains help identify the cell type of the masses, and in this case, the staining would most likely reveal B lymphocytes as the origin of the masses.