Msk-pathology

1. Why do patients with Achondroplasia have a larger head compared to limbs?

Due to excessive growth hormone secretion

As a result of maternal age effects

Because of a mutation in the IGF1 gene

*Because Chondrocyte proliferation inhibition due to Overactive FGFR3 leads to Defective ENDOCHONDRAL OSSIFICATION -Long bone growth=Longitudinal bone (Limbs) needs this type of ossification at epiphyseal growth plates,so they have short,thick,tubular long bones in appendicular skeleton(Limbs), while head,chest,flat bones of wrist,AXIAL skeleton(SPINE)don't need endochondrial ossification/cartilage mediator as they undergo Membranous ossification, thus their length can be normal.*Achondroplasia is MCC of Short-limbed dwarfism*Note PTH,GH,IGF1 are usually normal.*Boards also freakin WANT you to know that risk of Achondroplasia in progeny increases with Increased PATERNAL age(Contrast this with maternal age in down's)-achondroPPlasia-PPaternal.*Mental function, life span, and fertility not affected(Questions love to describe guy who has short limbs but becomes scientist or some cool guy with bunch of children lol)*Once again LINEAR growth at epiphyseal growth plate is inhibited.*+UW wants u to know that they can have some craniofacial abnormalities like depression of the nose root,forehead bulging.u should also contrast this short stature that preferentially affects Appendicular skeleton to Short stature caused by GH/IGF1 deficiency where appendicular skeleton(limbs) and Axial skeleton(Spine) are proportionate.

Achondroplasia is characterized by specific mechanisms affecting bone growth, leading to disproportion between the head and limbs. Problems with growth hormones or IGF1 mutations do not specifically correlate with the unique features of Achondroplasia. Additionally, paternal age is a known risk factor for the condition, not maternal age.

Explanation

Achondroplasia is characterized by specific mechanisms affecting bone growth, leading to disproportion between the head and limbs. Problems with growth hormones or IGF1 mutations do not specifically correlate with the unique features of Achondroplasia. Additionally, paternal age is a known risk factor for the condition, not maternal age.

2. Contrast Cancellous bone=trabecular (Spongy) bone with Compact bone(CORTICAL Bone) by locations/Diseases affecting them?

C. Osteoporosis mainly involves compact bone whereas hyperparathyroidism mainly affects cancellous bone.

B. Cancellous bone is primarily affected by osteomalacia. Compact bone is primarily affected by rickets.

*Cancellous bone is found in VERTEBRAL BODIES,Ends of Long bones.*Compact bone(Cortical Bone) is found in Most of the appendicular skeleton, provides support and MUSCLE ATTACHMENT sites.*Hyperparathyroidism(High PTH) usually results in SUBPeriosteal thinning as bone resorption takes place in Cortical(Compact bone)*Osteoporosis on the other hand mainly involves Spongy(Trabecullar,cancellous) bone>VERTEBRAL FRACTURES(MC),Fractures at the neck of the femur(50% is trabecular).Note that Osteoporosis does also affect Compact(Cortical bone) withOUT altering mineralization process, but yet spongy bone(More metabolically active) is preferentially affected.*know that LABS will be all normal in osteoporosis(Calcium,phosphate,PTH,ALP) but Calcium/ALP will be increased and Phosphate will be decreased in primary hyperparathyroidism.*If they make u choose lab abnormal in osteoporosis it is likely cortisosl(Hypercortisolism-like in cushing's syndrome can cause/potentiate osteooporosis)

A. Cancellous bone is found in the skull bones. Compact bone is found in the ribs.

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Cancellous bone, also known as trabecular or spongy bone, is typically found in locations such as vertebral bodies and ends of long bones. On the other hand, compact bone (cortical bone) is mostly found in the appendicular skeleton, providing support and muscle attachment sites. Diseases like hyperparathyroidism usually result in subperiosteal thinning in compact bone, while osteoporosis mainly affects spongy bone. Therefore, options A and B are incorrect as they provide inaccurate information regarding the locations and diseases affecting cancellous and compact bone. Option C is also incorrect as it fails to correctly contrast the locations and diseases affecting the two types of bones.

Explanation

Cancellous bone, also known as trabecular or spongy bone, is typically found in locations such as vertebral bodies and ends of long bones. On the other hand, compact bone (cortical bone) is mostly found in the appendicular skeleton, providing support and muscle attachment sites. Diseases like hyperparathyroidism usually result in subperiosteal thinning in compact bone, while osteoporosis mainly affects spongy bone. Therefore, options A and B are incorrect as they provide inaccurate information regarding the locations and diseases affecting cancellous and compact bone. Option C is also incorrect as it fails to correctly contrast the locations and diseases affecting the two types of bones.

3. Why do we have histologic findings of primary unmineralized spongiosa in medullary canals in osteopetrosis?

*Remember in osteopetrosis OsteoCLASTS can't do their job of bone resorption and unmineralized spongiosa can't be broken down/Replaced.*Thickened, dense bones can't adopt to stress properly and are prone to FRACTURE.*Hepatosplenomegaly is common finding due to extramedullary hematopoiesis(Instead of bone marrow which would normally give us blood cells,we have "Bone in Bone" leading to myelophthisic process), but compensation is not enough and often patients can have anemia,thrombocytopenia,leukpenia(RISK OF INFECTION).*Remember that defect at molecular level is Defective Carbonic Anhydrase2(Which would normally promote Creation of Acidic environment by OsteoCLASTS)*Thickened bone>Narrowing of foramina>Patients often present with Cranial nerve palsies(Can manifest as VISION or HEARING changes)*Treatment is Bone marrow transplant as you give new osteoclasts(Come from Bone marrow monocytes) which don't have that defect and can break down bone when needed.**Mutation in Carbonic anhydrase can lead to Renal tubular acidosis as this enzyme is needed for HCO3 reabsorbtion.*Patient can have Hydrocephalus due to narrowing of Foramen magnum.(Hydrocephalus can manifest with urinary incontinence,Cognitive impairment,Ataxia)

In osteopetrosis, there is an excess production of OsteoCLASTS leading to accumulation of unmineralized spongiosa in medullary canals.

The defect in osteopetrosis lies in OsteoBLASTS, which fail to create new bone matrix leading to unmineralized spongiosa.

Osteopetrosis is characterized by decreased Calcitonin levels, which results in accumulation of unmineralized spongiosa in medullary canals.

In osteopetrosis, the primary defect lies in OsteoCLASTS, not OsteoBLASTS, resulting in the inability to resorb bone properly. This leads to the accumulation of unmineralized spongiosa in medullary canals.

Explanation

In osteopetrosis, the primary defect lies in OsteoCLASTS, not OsteoBLASTS, resulting in the inability to resorb bone properly. This leads to the accumulation of unmineralized spongiosa in medullary canals.

4. What is a potential complication of a humerus midshaft fracture?

*In damage of DEEP branch of Brachial artery.*In damage of RADIAL nerve.(WRIST drop due to paralysis of extensors)*Supracondylar fracture can also cause damage to brachial artery.(Supracondylar fracture mostly results in median nerve damage<Proximal lesion)

In damage of MEDIAN nerve (Pronator teres syndrome)

In damage of AXILLARY nerve (Loss of sensation over deltoid)

In damage of ULNAR nerve (Cubital tunnel syndrome)

Humerus midshaft fracture is most likely to result in damage of DEEP branch of Brachial artery, leading to complications.

Explanation

Humerus midshaft fracture is most likely to result in damage of DEEP branch of Brachial artery, leading to complications.

5. What cells communicate through GAP junctions allowing calcium and cAMP to pass between them and are also responsible for laying down bone?

Chondrocytes

Osteoclasts

*OsteoBLASTS(Can lay down bone)

Adipocytes

Osteoblasts are responsible for bone formation, while osteoclasts are responsible for bone resorption. Chondrocytes are cartilage cells, and adipocytes are fat cells, neither of which communicate through GAP junctions in the same way osteocytes do.

Explanation

Osteoblasts are responsible for bone formation, while osteoclasts are responsible for bone resorption. Chondrocytes are cartilage cells, and adipocytes are fat cells, neither of which communicate through GAP junctions in the same way osteocytes do.

6. Which muscles are needed for complete shoulder abduction?

Infraspinatus, teres minor, latissimus dorsi

Pectoralis major, rhomboids, trapezius

Biceps brachii, brachialis, brachioradialis

*Till horizontal you need supraspinatus(First 15 degress) and from there to horizontal you need deltoid, after horizontal position you need serratus anterior.

The correct answer includes the supraspinatus for the first 15 degrees, deltoid from 15 degrees to horizontal, and serratus anterior after the horizontal position.

Explanation

The correct answer includes the supraspinatus for the first 15 degrees, deltoid from 15 degrees to horizontal, and serratus anterior after the horizontal position.

7. Contrast defects in collagen synthesis of OI and EDS...

OI is caused by autosomal recessive inheritance pattern.

*in OI you have Autosomal Dominant defect in formation Type ONE collagen as there is defect in formation of Triple Helix(3alpha chains), which makes up PROcollagen(needs disulfide and hydrogen bonds in triple alpha helix) could be due to defect in glycosylation of pro-a-chain hydroxylysine residues.*BLUE SCLERA is ver characteristic finding(defect in type 1 collagen>Choroidal veins are visible) and this blue sclera will help you to differ from Child abuse (characterized by SPIRAL fractures), child with OI may be deaf(fracture of middle ear bones)and with Blue/Brown teeth that easily rots(due to lack of dentin).*uw wants you to know that bone matrix is made up of Type1 collagen+Hydroxyapetite and thus Bone matrix FORMAITON is defective in OI(Contrast this with defect in Mineralizaiton in Vit.D deficiency)*In EDS you have defective cross linking between tropocollagen molecules(insoluble molecule in Extracellular space, these guys should aggreagate together by COVALENT lysine-hydroxylysine cross-linkage to create stable collagen fibrils), typically patient would have Hyperextensible skin,Joints(can present with Excessive hip rotation) and tendency to bleed(Classic type which affects Joints,Skin involves type 5collagen(5letters in CLASS) defect while Vascular type involves defect in Type 3 found in vessels/organs>Organ rupture,berry/aortic aneurysm.)

In EDS, the defect is in the formation of Type TWO collagen.

Characteristic finding in OI is hyperextensible skin.

The correct answer provides a detailed explanation of the defects in collagen synthesis in both OI and EDS. The incorrect answers fall short as they provide inaccurate information about the inheritance pattern of OI, the type of collagen affected in EDS, and the characteristic finding in OI.

Explanation

The correct answer provides a detailed explanation of the defects in collagen synthesis in both OI and EDS. The incorrect answers fall short as they provide inaccurate information about the inheritance pattern of OI, the type of collagen affected in EDS, and the characteristic finding in OI.

8. A male patient with Nocturia and frequency complains of back pain which is NOT relieved by rest or changing position. What should you consider as a possible diagnosis?

Urinary tract infection as a cause of back pain

Muscle strain from physical activity as a cause of back pain

Dehydration leading to muscle cramps as a cause of back pain

*back pain which is NOT relieved by rest,changin position, should make you think of neoplastic bone disease esp. in older male POSSIBLE signs of prostate cancer(Loves to metastasize to bone, note that Breast is overall most common metastases to bone, so obv. vignette could give you patient with breast cancer metastases to bone.)

Back pain that is not relieved by rest or changing position is concerning for neoplastic bone disease, particularly in older males. Prostate cancer and breast cancer are known to metastasize to bone, presenting with similar symptoms.

Explanation

Back pain that is not relieved by rest or changing position is concerning for neoplastic bone disease, particularly in older males. Prostate cancer and breast cancer are known to metastasize to bone, presenting with similar symptoms.

9. Damage to the region of ribs (from 9-11) on the left side could damage?

1)Most likely Spleen(Overlied by 9-11 ribs)2)Most likely liver.3)Most likely left kidney

Gallbladder

Pancreas

Stomach

The spleen is located beneath the 9-11 ribs on the left side.

Explanation

The spleen is located beneath the 9-11 ribs on the left side.

10. Osteoporosis risk factors include high/low body fat?

High body fat increases your risk of osteoporosis.

Body fat percentage does not affect the risk of osteoporosis.

*Low body fat(Less estrogen) increases your risk of osteoporosis.*everyone knows about smoking,corticosteroids and alcohol and lack of physical activity, so don't forget the weird one.*Note:Patient would most likely be Caucasian(more common than in blacks)*Peak bone mass (reached at 30 years of age)depends on genetics (Vit D receptor variation), diet and determines the risk of developing osteoporosis(It is higher in Males and thus they have lower risk, same is true for black vs white females, white females have higher risk of osteoporosis as black females have more bone mass to start with)*HISTOLOGICALLY osteoporosis is characterized by TRABECULAR THINNING+FEVER INTERCONNECTIONS(DISRUPTION OF NORMAL BONE ARCHITECTURE)

Both high and low body fat can increase the risk of osteoporosis.

Low body fat, which is associated with lower estrogen levels, increases the risk of osteoporosis as estrogen helps protect bone density. In contrast, high body fat may provide some cushioning effect for bones, reducing the risk of osteoporosis. It is essential to manage body fat levels to maintain bone health.

Explanation

Low body fat, which is associated with lower estrogen levels, increases the risk of osteoporosis as estrogen helps protect bone density. In contrast, high body fat may provide some cushioning effect for bones, reducing the risk of osteoporosis. It is essential to manage body fat levels to maintain bone health.

11. Which of the following is a characteristic presentation of Vitamin D deficiency?

*Defective mineralization of the matrix/Cartilogenous growth plates occurs in growing bones causing weight-bearing bones to bow laterally (genu varus-medial angulation),Epiphysial widening and metaphyseal cupping/fraying are commonly observed on xray of RICKETS(Result of vitamin D def in children)other common findings include bony prominence at the costochondral junction (rachitic rosary=due to Osteoid deposition in costochondral junction), indentations in the lower ribs (Harrison’s sulci), softening of the skull= (craniotabes), hypocalcemia, hypophosphatemia hypertonia, and growth retardation , don't forget Pectus craniatum (pigeon breast=inward benging of the ribs with anterior protrusion of the ribs).*Some characteristic findings of Osteomalacia which is result of Vit.D def in adults are "Pseudofractures"-visulaized as looser zones+Xray would show osteopenia.

Formation of pseudofractures in long bones

Increased secretion of PTH leading to hypercalcemia

Decreased ALP activity in osteoblasts

Vitamin D deficiency leads to defective mineralization of the matrix in growing bones causing weight-bearing bones to bow laterally. This presentation is characteristic of rickets in children and osteomalacia in adults.

Explanation

Vitamin D deficiency leads to defective mineralization of the matrix in growing bones causing weight-bearing bones to bow laterally. This presentation is characteristic of rickets in children and osteomalacia in adults.

12. What is the function of T-tubules in muscle cells?

Membrane proteins involved in regulating cell division in muscle tissue.

*The are Uniformly-distributed invaginations of the sarcolemma (muscle cell membrane) extending into each muscle fiber.*They allow Uniform contraction of all muscle fibrils, due to their uniform distribution*T-tubule depolarization-induced SR Ca2+ release is controlled by dihydropyridine receptors.*Ryanodine receptors are located on Sarcoplasmic reticulum.

A form of energy storage within muscles.

Specialized organelles responsible for protein synthesis in muscle cells.

13. Which malignancy should a patient with the following symptoms be screened for? Malar rash, erythomatous periorbital rash, pink/purple Gottron patches on knuckles, muscle weakness, increased CK levels, Anti-Jo1 antibody +, Anti-SRP antibody +, Anti-Mi2 antibody +, biopsy shows perimysial atrophy with CD4+T cell infiltrate.

Lung cancer

Prostate cancer

Breast cancer

*GASTRIC carcinoma,Generally any cancer.*Dermatomyositis has been associated with increased risk of occult malignancy(Cancer detected at advanced stage)*Rash will help you to differ DERMAtomyositis from Polymyositis but Important testable fact is that in contrast to Perimysial atrophy with CD4Tcell infitrate, in Polymyositis we have CD8+Tcells and ENDomysial inflammation.(Call me at 8 P.M and we END this relationship.*ANA is often + but it is not specific, Anti-Jo1 is way more specific finding for dermatomyositis.(uw wants u to know that)

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Patients with dermatomyositis are at an increased risk for occult malignancies, with gastric carcinoma being a commonly associated cancer.

Explanation

Patients with dermatomyositis are at an increased risk for occult malignancies, with gastric carcinoma being a commonly associated cancer.

14. A 65 year-old female is admitted with acute back pain, loss of height, and kyphosis. Her bone mineral density scan (DEXA scan) shows a T score of exactly -2.5. What fractures is she at increased risk for? What are likely PO4 (3-) and Ca(2+) levels in her serum?

*She could have vertebral compression fractures, Colles fracture(Distal radius effected), Fracture of femoral NECK.*T score EQUAL to or Less than- 2,5 SD is daignostic for osteoprosis, fragility fracture of hip/vertebra is also diagnostic.***Her Calcium and Phosphate levels would be NORMAL(They love to test this)*Bisphosphonates(inhibitors of osteoclast activity by binding hydroxyapetite) are DOC.*Teriparatide(recombinant PTH that increases osteoblast activity)*SERM(Like Raloxifene)*Calcitonin(Normally released from C cells of thyroid in response to high levels of calcium in blood and promotes buidling of the bone,while decreasing calcium levels in blood.)*Denosumab(antibody not against RANK but against LIGAND of RANK, thus mimics osteoprotegerin and inhibits maturation of OsteoCLASTS)*Remember that Weight-bearing exercises(NOT SWIMMING) with proper intake of Calcium and Vitamin D are prophylactic measures.*If patient is smoker he needs to stop smoking(Inhibits OsteoBLAST activity)

Her Calcium and Phosphate levels would be elevated.

She is at increased risk for pelvic fractures, skull fractures, and shoulder fractures.

The recommended treatment is only Bisphosphonates.

15. Why do postmenopausal women have an increased risk of Type 1 osteoporosis?

As a result of an overproduction of Calcium in the body leading to bone weakening.

*Because normally Estrogen would increase OsteoBLAST activity and Decrease OsteoClast actity(thus favor formation,over resorption)*This effect is medated by Estrogen mediated inhibition of IL1,6,TNF secretion.*IL1,6TNF cytokines promoete Receptor Activator of Nuclear factor Kb(RANK )interaction with its ligand, while they also antagonize expression of OsteoProteGerin,< which is a receptor produced by osteoBLASTS that inhibits RANKL(also produced by osteoblasts) interaction with its receptor(RANK), thus when when there is no estrogen mediated inhibition of these guys they inhibit Osteoprotegerin's effects and also directly stimulate RANKL-RANK interaction>Increased osteoCLASTogenesis.(BTW denosumab is monoclonal anitbody against RANKL and helps with osteoporosis)*well FA just wants you to know that Estrogen inhibits apoptosis in bone forming osteoblasts and induces apoptosis in bone resorbing osteoclasts.<So when u lack it>too much resorption with not enough formation.

Because postmenopausal women are more likely to engage in high-impact exercises that weaken bone structure.

Due to a lack of Vitamin C in the diet leading to decreased bone density.

Postmenopausal women have an increased risk of Type 1 osteoporosis due to the impact of estrogen on bone formation and resorption, leading to decreased bone density and increased bone resorption. This imbalance is a key factor in the development of osteoporosis in this population.

Explanation

Postmenopausal women have an increased risk of Type 1 osteoporosis due to the impact of estrogen on bone formation and resorption, leading to decreased bone density and increased bone resorption. This imbalance is a key factor in the development of osteoporosis in this population.

16. What are some key features of metabolic abnormality of bone?

Increased thickness of cortical and trabecular bone, dark appearance on radiograph (osteoporosis), excess production of both osteoid and mineralized bone.

Normal thickness of cortical and trabecular bone, normal appearance on radiograph, no change in osteoid or mineralized bone.

Fluctuating thickness of cortical and trabecular bone, mixed appearance on radiograph, increased production of osteoid but decreased mineralized bone.

*Decreased thickness of cortical and trabecular bone.*Radiograph:washed-out appearance(Osteopenia)*Loss of Both Osteoid(Organic bone matrix) and Mineralized bone.

17. Male Patient with an increasing hat size, LION like face and progressive hearing loss (auditory foramen narrowing) suffers multiple long bone fractures. Labs show only elevated ALP levels, everything else is normal. Most likely cause of death?

*High-output heart failure is the most common cause of death in osteitis deformans (Paget disease of bone) due to Increased blood flow through ArterioVenous shunts(Heart heas to push against these shunts), they also have increased risk of osteogenic sarcoma(Due to osteoblast overactivity).

Acute kidney failure due to chronic ALP elevation and subsequent renal damage.

Respiratory failure due to compression of the airways by an enlarged skull and facial bones.

Metabolic acidosis caused by an overproduction of alkaline phosphatase leading to systemic pH imbalance.

18. In osteitis fibrosa cystica due to primary hyperparathyroidism, levels of : Ca2+, PO43-, ALP, and PTH levels?

Ca2+ and PTH levels increase while PO43- and ALP decrease

Ca2+ and PO43- increase while ALP and PTH levels decrease

PO43- and ALP increase while Ca2+ and PTH levels decrease

*PTH,Calcium and ALP increase while the PO43- level is decreased(PTH promotes excretion of phosphate in urine)*Distinguishing characteristic of bone in patients with osteitis fibrosa cystica is that patients have brown tumors (due to fibrous replacement of bone) /is also characterized by subperiosteal thinning.*Cystic changes in bone predispose patients to fractures(classic presentation)*NOTE:Patient can present with headaches, bone pain, or abdominal pain,urinary tract caliculus all due to HYPERcalcemia associated with hyperparathyroidism.

Osteitis fibrosa cystica due to primary hyperparathyroidism is characterized by specific changes in the levels of PTH, calcium, phosphate, and ALP. Understanding these changes is crucial for proper diagnosis and treatment.

Explanation

Osteitis fibrosa cystica due to primary hyperparathyroidism is characterized by specific changes in the levels of PTH, calcium, phosphate, and ALP. Understanding these changes is crucial for proper diagnosis and treatment.

19. Normally, osteopetrosis is characterized by normal calcium values. What happens if calcium values are decreased?

*It indicates poor prognosis,Malignant,severe form of the disease.

Decreased calcium values indicate a benign, less severe form of osteopetrosis.

Hypocalcemia is not related to osteopetrosis.

Low calcium levels suggest a temporary fluctuation in the disease but not necessarily a poor prognosis.

In osteopetrosis, a decrease in calcium values indicates a more severe and aggressive form of the disease with a poor prognosis.

Explanation

In osteopetrosis, a decrease in calcium values indicates a more severe and aggressive form of the disease with a poor prognosis.

20. Contrast lab values in primary and secondary hyperparathyroidism.

*Primary-High Ca2+, low PO43-, high ALP, high PTH(Caused by excess PTH secretion from adenoma/Carcinoma,parathyroid hyperlasia)*Secondary-Low Ca2+, high PO43-, high ALP, high PTH(Response to compromised excretion of Phosphate and excess excretion of calcium in CKD)

High Ca2+, high PO43-, low ALP, low PTH

Low Ca2+, low PO43-, high ALP, low PTH

High Ca2+, low PO43-, normal ALP, low PTH

Primary hyperparathyroidism is characterized by increased levels of calcium, low phosphate, high alkaline phosphatase, and high levels of parathyroid hormone (PTH) due to overproduction. In contrast, secondary hyperparathyroidism presents with low calcium levels, high phosphate, high alkaline phosphatase, and high PTH due to response to compromised excretion of phosphate and excess excretion of calcium in chronic kidney disease (CKD).

Explanation

Primary hyperparathyroidism is characterized by increased levels of calcium, low phosphate, high alkaline phosphatase, and high levels of parathyroid hormone (PTH) due to overproduction. In contrast, secondary hyperparathyroidism presents with low calcium levels, high phosphate, high alkaline phosphatase, and high PTH due to response to compromised excretion of phosphate and excess excretion of calcium in chronic kidney disease (CKD).

21. A 34 year-old female presents with a visible mass in the knee region. X-ray reveals a 'Soap bubble' appearance and biopsy shows spindle-shaped cells with multinucleated giant cells. Is the tumor benign or malignant, and where is it located?

Ewing's sarcoma is a benign tumor that commonly affects older individuals in the age group of 50 and above.

*Osteoclastoma=Giant Cell tumor is a Benign but locally aggressive tumor that usually involves Epiphyseal Ends of Long bones.Note patient is in age group of 20-40 and is female(More common in females of young age)*Giant cell tumors express high levels of RANKLigand.(Induces formation of Multinucleated osteoCLASTS)*Remember EPI(Epiphysis) PEN IN GIANT's ASS(Rhymes :P)*Giant cell tumor is ONLY tumor in epiphysis and it arises in distal femur/proximal tibia in same region as osteosarcoma(In knee region) but osteosarcoma arises in Metaphysis and can produce osteoid.*NOTE even though OsteoClastoma(Giant cell tumor) is benign it can recur.(<KNOW THAT)

Osteosarcoma is a malignant tumor that usually arises in the epiphysis of long bones.

Chondrosarcoma is a benign tumor that involves the metaphysis of long bones.

22. 22 year old man presents to clinic with painLESS, hard mass which doesn't move on left leg (which appears to be shorter than right one). Piece of mature bone with cartilage cap, in metaphysis of bone is detected. Is it a benign/malignant tumor?

*Bony exostosis with cartilaginous(chondroid)cap esp in male <25 years old should make you think of osteochondroma which is MOST COMMON BENIGN BONE TUMOR and arises from lateral projection of growth plate.*You should screen patient for Chondrosarcoma as this benign tumor can transform into chondroSarcoma(Malignant tumor resistant to chemo and radiotherapy), chondrosarcoma will most likely present in Older(transformation needs time) male described as SESSILE GLISTENING MASS IN Medullary cavity mostly in PELVIS/CENTRAL skeleton, they love to erode in surrounding cortex.)*Remember osteochondroma by saying OMMMMM like you meditate(OsteoCHONDROMA-Metaphysis)*Don't confuse Osteochondroma with chondroma which is benign cartilage producing tumor that arises in medulla of small bones of Hands and feet.

Osteosarcoma is a malignant bone tumor that most commonly affects adolescents and young adults. It presents with bone pain and swelling, often in the metaphysis of long bones, and has a high propensity for metastasis to the lungs.

Fibrous dysplasia is the most common benign tumor of the bone that presents with pain, swelling, and deformity. It typically affects the long bones like the femur and tibia.

Ewing sarcoma is a malignant tumor that commonly presents in the diaphysis of long bones in children and young adults. It is characterized by aggressive bone destruction and is treated with a combination of chemotherapy, surgery, and radiation therapy.

23. What is the most likely tumor suppressor loss of function in a 16 year-old boy with osteosarcoma, who has a family history of Breast cancer and Soft tissue sarcoma?

*Patient has osteosarcoma(MALIGNANT proliferation of OsteoBLASTS -Presents with Pathologic fracture due to weakning of bone,most likely associated with Li-fraumeni syndrome which involves GERMLINE P53 tumor suppressor loss of function.(Good question)*If patient was baby with squint eye with white reflection in the pupil/swollen/shrunken/red sore eye without inflammation, with palpable mass in knee region(Osteosarcoma loves METAphysis of long bones and often appears in knee region), then answer would be Loss of function of Rb1 Tumor suppressor.(Retinoblastoma is predisposing factor to osteosarcoma)*History of Radiation,Bone infarcts,Paget's disease(osteitis deformans) should also make you suspect osteosarcoma as they are predisposing factors too.*Treatment of osteosarcoma is surgery with En bloc resection with limb salvage(large blocks are removed but structure of organ is retained)+Chemotherapy.*Osteosarcoma is second MC malignant tumor of bone(N1 is multiple myeloma) patient will most likely be male (10-20 years of age or more than 65 hence the :BIMODAL age distribution, in children it is the most common bone sarcoma(More common than ewings)*LAME MNEMONIC which helped me :P<>OsteoSarcoma loves BIsexual(Bimodal) MEn.(MEtaphysis)

Loss of function of PTEN tumor suppressor

Loss of function of BRCA1 tumor suppressor

Loss of function of Rb1 tumor suppressor

24. Name conditions that can affect diaphysis.

Osteoporosis

Fibrous dysplasia

*Ewing sarcoma, Multiple Myeloma(MC malignant tumor of the bone)*Some lame mnemonics which will make these facts stick:P*Mountain DEW(Diaphysis,EWing sarcoma)*Multiple DIcks in MY pOcket(Multiple MYelOma-DIaphsysis)

Rheumatoid arthritis

Diaphysis can be affected by conditions such as Ewing sarcoma and Multiple Myeloma, but not by Osteoporosis, Rheumatoid arthritis, or Fibrous dysplasia.

Explanation

Diaphysis can be affected by conditions such as Ewing sarcoma and Multiple Myeloma, but not by Osteoporosis, Rheumatoid arthritis, or Fibrous dysplasia.

25. Patient complains of nighttime pain in leg, xray shows 1.5 cm mass in diaphysis of the bone. What is the most likely diagnosis?

Osteosarcoma

Osteochondroma

Osteoporosis

*Patient most likely has Osteoid osteoma(Benign tumor of OsteoBlasts which prouces osteoid, surrouned by rim of reactive bone) arises on CORTEX in diaphysis of long bone, and is characterized by nighttime pain and mass in diaphysis(PGE2 mechanism of bone pain-Hence Aspirin Relieves the pain)+(I remember that it effects diaphysis by: nighD Dime Pain in Diaphysis=osDeoiD osDeoma.)*Don't confuse Oseoid osteoma(Key:radiolucent nidus surrounded by sclerotic bone,located at the end of tibia/femur)with Osteoma-also benign tumor of bone which mostly affects FACE.*Osteoma has association with Gardner syndrome(variant of familial adenomatous polyposis - autosomal dominant disease and is characterized by GI polyps, multiple osteomas, and skin and soft tissue tumors, epidermoid cysts, desmoid tumors=fibrosis of anterior abdominal wall,RETROPERITONEAL FIBROMATOSIS-Nonneoplastic prolferation of fibroblasts, Garnder syndrome also has association with PAPILLARY thyroid carcinoma). *So they can describe to you guy with osteoma and ask you about conditions associated with Gardner syndrome, so know these.

Osteoid osteoma is a benign tumor of OsteoBlasts which produces osteoid, surrounded by a rim of reactive bone. It arises in the cortex in the diaphysis of a long bone, characterized by nighttime pain and a mass in the diaphysis.

Explanation

Osteoid osteoma is a benign tumor of OsteoBlasts which produces osteoid, surrounded by a rim of reactive bone. It arises in the cortex in the diaphysis of a long bone, characterized by nighttime pain and a mass in the diaphysis.

26. A 56 year-old male presents with SOB, cough, morning joint stiffness, tender swollen MCP and PIP joints, rheumatoid nodules, fever, weight loss, pleuritic chest pain, and diffuse chest pain. What labs are most likely to show?

Anti-DNA Antibody and ANA

Hepatitis B Surface Antigen and H. pylori IgG Antibody

*His medical history could reveal SILICA exposure, SMOKING(Both increase risk of RA).*Labs could show Rheumatoid Factor(igM antibody against Fc region of igG, IC deposition is responsible for systemic signs as RA is example of Type 3 hypersensitivity)/ Anti-CCP Antibody(More SPECIFIC for RA than Rheumatoid factor is), patient is likely to be DR4+(MHC2) as it has association with RA.(They can make a good integration with immuno chapter and ask you what conditions patient is also at increased risk for and these are Addison's disease and Type ONE DM, these 3 conditions have strong association with DRA-4)*RA is autoimmune disease(has genetic+environmental component,more common in females) affecting Synovium, inflammatory cells releasing cytokines result in formation of overhanging proliferative granulation tissue(Pannus) in joint space resulting in erosion of ARTICULAR cartilage and bone.*Hey but note that our particular patient doesn't just have RA he has CAPLAN SYNDROME(basically RA+Pneumoconiosis), +he also has some extrarticular manifestations of RA(Pleuritis,Pericarditis) *uw wants you to know that ATROPHY of Interosseous muscle is characteristic of Rhematoid arthritis.*Note IC deposition in joints leads to activation of complement and neutrophil chemotaxis(C5a), as classical pathway of complement is overactive C3 levels will be decreased(less of it is left) in SYNOVIUM.(In serum C3 levels can be normal/higher according to poppie)

Thyroid Peroxidase Antibodies and Cyclic Citrullinated Peptide

27. What joint findings are you likely to find in a patient with rheumatoid arthritis?

Metacarpal Bossing, joint hypermobility, presence of Heberden nodes, normal joint space width, no soft tissue swelling

Cubital deviation of fingers, boutonniere deformity, sparing of PIP joints, saucerization of bone, periarticular osteophytes

RADIAL deviation of fingers, sparing of Heberden nodes, joint space widening, absence of erosions, increased joint flexibility

*ULNAR(medial to anatomic position) deviation of fingers, deviation of fingers and ankylosis is due to Myofibroblast contraction(Components of pannus=grnaulation tissue)*Swelling,pain,stiffnes with symmetric joint involvement.*SWAN Neck deformity(PIP HYPEREXTENSION and DIP FLEXION contrast this with Boutonniere deformity=PIP Flexion+DIP HYPERextension just remember swan neck and deduce boutonniere as opposite of it), there are no Heberden nodes/inflammation in DIP thus it is marked as SPARED ,1st CMC is also spared in RA, they are affected in osteoarthritis so it is no BS)*Joint space narrowing(remember granulation tissue=PANNUS contains Myofibroblasts which CONTRACT)*Juxtarticular osteopenia(when inflammation spreads to bone)*Erosions*Soft tissue swelling*SUBCHONRAL CYSTS.(Like in OA)*Synovial fluid with inflammatory cells,WBC>2000/mm3.*All these are characteristic findings of rheumatoid arthritis*Our Patient is also likley to have Sjogren's syndrome(Dry mouth,eyes hence sand and can't chew crakcer) with RA(in fact presence of RA helps you to differ this condition from Sicca syndrome which is very similar condition but without RA)*If patient had Neutropenia+Splenomegaly with RA he would also be diagnosed with FELTY syndrome.*Chronic inflammatory conditions like RA increase risk of developing Anemia of chronic disease( due to APR-Hepcidin release which blocks use of iron stored in macrophages) and AA amyloidosis(Multisystem secondary amyloidosis, with amyloid consisting of AA fibrils), note that primary leukocyte abnormality in chronic inflammatory conditions like RA is MonoCYTOSIS.*They love to give you patient with RA that presents with cyst behind the knee region and make you diagnose baker's cyst.(Ey want q?: Patient with rheumatoid arthritis presents with enlarging mass in LATERAL popliteal fossa overlying tendon of the biceps femoris, they ask Motor deficit, answer:LOSS Of DORSIFLEXION(FOOT DROP) , remember baker cyst is basically enlargement of popliteal bursa(between gastrocnemius-semimembranous) which is inflamed and filled with synovial fluid and is PULASTILE(differ from aneurysm by ultrasound), enlargement laterally/aspiration of the cyst can damage common FIBULAR=PERONEAL nerve.)*Medially extension of cyst(More often) can compress TIBIAL nerve which would manifest with changes in sensation along PLANTAR surface of the foot(Contrast with dorsal surface in peroneal nerve damage) also with proximal tibial nerve damage patient can't INvert/Plantar flex the foot contrast this with peroneal nerve where he can't dorsiflex/Evert)+They Love to test that with tibial nerve damage patients Can't curl toes/walk on tiptoes.*prominence of the tendons in the extensor compartment of the hand, is also characteristic finding in patient with RA.*Poppie wants you to know that in Serum we have Increased/normal C3 while in Synovium C3 is Decreased(excessive activation in sites of deposition>depletetion)*Also know that on serum protein electrophoresis u will have POLYCLONAL gammopathy due to increase in igG(chronic inflammation)

These are all characteristic joint findings of rheumatoid arthritis, indicating inflammation, joint space narrowing, erosions, and other changes associated with the disease.

Explanation

These are all characteristic joint findings of rheumatoid arthritis, indicating inflammation, joint space narrowing, erosions, and other changes associated with the disease.