Internal Medicine Exam Rheumatology and Orthopedics 5 — Questions and Answers
Question 1: A 60-year-old man on allopurinol develops a severe desquamating rash with mucous membrane involvement. Which HLA allele is strongly associated with this severe drug reaction?
- HLA-B27
- HLA-B*58:01 (Correct answer)
- HLA-DR4
- HLA-DQ2
Correct answer: HLA-B*58:01
HLA-B*58:01 is strongly associated with allopurinol-induced Stevens-Johnson syndrome and toxic epidermal necrolysis, particularly in Asian populations.
Question 2: A 55-year-old woman with RA develops leg ulcers, splenomegaly, and neutropenia. What is the most likely diagnosis?
- Vasculitis
- Felty's syndrome (Correct answer)
- Large granular lymphocyte syndrome
- Drug-induced agranulocytosis
Correct answer: Felty's syndrome
Felty's syndrome is the triad of rheumatoid arthritis, splenomegaly, and neutropenia, associated with severe seropositive RA.
Question 3: A 40-year-old man develops severe low back pain radiating to the buttocks, alternating sides, worse in the morning and improving with exercise. MRI shows sacroiliac joint edema. Which HLA type is most commonly associated?
- HLA-DR3
- HLA-B27 (Correct answer)
- HLA-DR4
- HLA-B5
Correct answer: HLA-B27
HLA-B27 is present in approximately 90% of patients with ankylosing spondylitis and is associated with all seronegative spondyloarthropathies.
Question 4: A patient with polymyositis has elevated CK, muscle weakness, and is started on prednisone. Two months later the CK normalizes but weakness worsens. What should be suspected?
- Steroid myopathy (Correct answer)
- Inadequate immunosuppression
- Paraneoplastic myopathy
- Inclusion body myositis
Correct answer: Steroid myopathy
Steroid myopathy causes worsening weakness despite normalized CK, presenting a diagnostic dilemma; it is proximal, non-inflammatory, and improves with steroid dose reduction.
Question 5: A 65-year-old woman presents with shoulder and hip girdle pain and stiffness lasting >45 minutes in the morning, ESR of 85 mm/hr, and rapid response to low-dose prednisone. What is the diagnosis?
- Fibromyalgia
- Polymyalgia rheumatica (Correct answer)
- Polymyositis
- Giant cell arteritis
Correct answer: Polymyalgia rheumatica
Polymyalgia rheumatica presents with bilateral shoulder and hip girdle stiffness, markedly elevated ESR, and dramatic response to low-dose prednisone (15-20 mg/day).
Question 6: A 30-year-old woman with SLE is found to have a positive lupus anticoagulant and has a history of one DVT. What is the recommended long-term management?
- Antiplatelet therapy with aspirin alone
- Indefinite anticoagulation with warfarin (INR 2-3) (Correct answer)
- 6-month anticoagulation with DOAC
- Hydroxychloroquine alone
Correct answer: Indefinite anticoagulation with warfarin (INR 2-3)
SLE patients with antiphospholipid antibodies and thrombotic events require indefinite anticoagulation with warfarin targeting INR 2-3, as DOACs have shown inferior outcomes.
Question 7: A 45-year-old man with chronic tophaceous gout requires urate-lowering therapy but has failed allopurinol due to intolerance. Which alternative urate-lowering agent works by a different mechanism?
- Colchicine
- Probenecid
- Febuxostat (Correct answer)
- Benzbromarone
Correct answer: Febuxostat
Febuxostat is a non-purine selective xanthine oxidase inhibitor that lowers uric acid by the same pathway as allopurinol but can be used in patients intolerant to allopurinol.
Internal Medicine Exam Rheumatology and Orthopedics 5
A 60-year-old man on allopurinol develops a severe desquamating rash with mucous membrane involvement.
Which HLA allele is strongly associated with this severe drug reaction?