MSK- UWORLD

Question 1

87- Q 4. Inheritance pattern of androgenic alopecia?

Answer 1

polygenic with variable expressity

Question 2

87- Q 31. Side effect on skin for topical glucocorticoid?

Answer 2

atrophy of DERMIS

Question 3

88- Q 2. Explain why kids have bowing leg in rickets

Answer 3

lack of Ca2+ leads to UNMINERALIZED OSTEOID. Incomplete mineralization of osteoid leads to poor quality soft bone.

• normal bone mineralization requires Ca2+ and phosphate

Question 4

88- Q 7. Describe bone biopsy finding in Paget

Answer 4

MOSAIC pattern of woven and lamellar bone with prominent CEMENT LINE

• buzzwords: MOSAIC and CEMENT LINE

Question 5

88- Q 9. monoclonal antibody drugs, after that vasculitis with fibrinoid necrosis: What is going on?

Answer 5

serum sickness: type 3 hypersensitivity reaction

• hallmark of type 3 hypersensitivity reaction are systemic symptoms (fever, urticaria) and vasculitis
• buzzwords:
  1. MONOCLONAL ANTIBODY DRUG (or penicillin, these two can be haptens)
  2. VASCULITIS

Question 6

88- Q 23. How UVA induces photoaging of skin?

Answer 6

UVA -> decreased collagen FIBRIL production

-> wrinkling

Question 7

88- Q 27. Supracondylar humeral fracture with anterolateral displacement: what nerve is damaged?

Answer 7

Radial n.

• this is tricky question. normally supracondylar fracture is associated with median n. damage. but with ANTEROLATERAL dislocation of fracture humerus, it is RADIAL N. that is getting damaged.

Question 8

88-Q 37. Difference between UV and radiation in terms of DNA damage? repair mechanism?

Answer 8

UV: thymine dimerization -> nucleotide excision repair

Radiation: double strand break-> non-homologous end joining

Question 9

89- Q 3. Ehlers-Danlos vs. Marfan: What is similarity and difference between these two?

Answer 9

Similarity

1. BOTH hypermobile joints
2. aortic aneurysm

Differences

• Ehlers-Danolos: collagen cross-linking defect, easy bruising, berry aneurysm
• Marfan: fibrillin (glycoprotein sheaths around elastin) defect, long extremities, MVP, pectus excavatum, lens sublaxation
• BOTTOM LINE: Ehlers-Danlos is unique in terms of EASY BRUISING and BERRY ANEURYSM (which makes sense as vascular type collagen defect (collagen 3) is involved, while Marfan is fucked up in many other ways

Question 10

89- Q 16. Joint pain, previous history of polycythemia vera. Diagnosis?

Answer 10

gout!

myeloproliferative disorder is one of causes of gout. More cell proliferation, more purine breakdown, more uric acid production

Question 11

89- Q 29. What is exocrine? vs. endocrine?
Define three types of exocrine below, example of each?
- merocrine
- holocrine
- apocrine

Answer 11

Exocrine: release through duct
Endocrine: release into blood stream

• merocrine: exocytosis, ex- salivary gland
• holocrine: burst! lysis, ex- sebaecus gland (acne)
• apocrine: membrane bound vesicles, ex- mammary gland (think milk in vesicles-마시는 캡슐 요구르트)

Question 12

90-Q 8. Which nerve innervates latissimus dorsi?

Answer 12

thoracodorsal n.

• thoracoDORSal= latissimus DORSi

Question 13

90- Q 15. Leser-Trelat sign is what type of skin disorder?

Answer 13

seborrheic keratosis

Question 14

90- Q 16. Which nevi extends to dermis?

Answer 14

compound nevi

also melanoma for sure

Question 15

90- Q 18. Where does quadriceps muscle attach to distally?

Answer 15

tibial tuberosity

Question 16

91- Q 2. Bilateral pain in lower extremities and bak, pain relieved by leaning forward. What is diagnosis? Commonly due to what?

Answer 16

spinal stenosis
- commonly due to thickening of ligamentum flavum ( spinal ligament in posterior side)

• buzzword: pain relieved by leaning forward

Question 17

91- Q 3. How drugs involved in drug-induced SLE are get metabolized?

Answer 17

hepatic acetylation

Question 18

91- Q 9. What is molecular target of anti-Jo-1 (polymyositis??

Answer 18

histidyl tRNA synthase

Question 19

91- Q 28. skin changes after food consumption: two differential diagnosis? how do they grossly look different?

Answer 19

• eczema (atopic dermatitis): pruritic eruption (spongiosis)
• dermatitis herpetiformis: GROUPED vesicles, pruritic papules, sometimes bullae
• key difference is basically whether it is vesicles or not. They BOTH are pruritic

Question 20

91- Q 30. Two differential diagnosis for mast cell mediated skin manifestations? how do they grossly look different?

Answer 20

• eczema: pruritic eruptions

- urticaria (hives): smooth papule or plaque (big)- superficial dermal edema

Question 21

93- Q 1. What vasculitis can cause wrist/foot drop?

Answer 21

eosinophilic granulomatosis with polyangiitis (Churg-Strauss)

Question 22

95- Q 7. Patient shows weakness, papules on hands. what disease is this? What another disease may be associated with it?

Answer 22

dermatomyositis
* papules on hands= mechanics hands

• associated with OCCULT MALIGNANCY (OVARIAN CANCER is most common)
• NOTE: I picked the porphyria cutaneous tarda

Two mistakes I made:

1. Q was asking ASSOCIATED disease, not disease itself
2. I overlooked patient’s history of weakness. They just showed hand picture, for which porphyria cutaneous tarda also may present similarly (photosensitivity)

Question 23

98- Q 14. Key difference in back pain due to degenerative vs. malignancy?

Answer 23

dengenerative- pain relieved by rest

maliganancy- constant pain, not relieved by rest

Question 24

98- Q 38. Bone metastasis findings in imaging studies have two possible cases- sclerotic and osteolytic. What is each? example?

Answer 24

• sclerotic: osteoblastic activity, bone metastasis like prostate cancer
• osteolytic: osteoclastic activity, paraneoplastic syndrome like squamous cell carcinoma of lung or renal cell carcinoma

Question 25

114- Q28. List three possible causes of radial nerve injury. How does each present?

Answer 25

• humeral midshaft fracture: wrist drop
• axillar compression (crutches): wrist drop
• supinator canal injury: ONLY FINGERS drop
  => deep branch of radial nerve (posterior interosseous nerve) pass through supinator canal, which innervates muscles for FINGER EXTENSION