Internal Medicine Exam Common Rheumatologic Disorders 2 — Questions and Answers
Question 1: A 35-year-old woman presents with a malar rash, arthralgias, and positive ANA with anti-dsDNA antibodies. Urinalysis shows proteinuria and RBC casts. Which class of lupus nephritis carries the worst prognosis if untreated?
- Class I (minimal mesangial)
- Class III (focal proliferative)
- Class IV (diffuse proliferative) (Correct answer)
- Class V (membranous)
Correct answer: Class IV (diffuse proliferative)
Class IV (diffuse proliferative) lupus nephritis is the most severe form and carries the worst renal prognosis without aggressive immunosuppressive therapy.
Question 2: A 55-year-old man with long-standing rheumatoid arthritis develops new-onset wrist drop. Which extra-articular manifestation of RA is most likely responsible?
- Felty syndrome
- Mononeuritis multiplex due to rheumatoid vasculitis (Correct answer)
- Carpal tunnel syndrome
- Amyloid neuropathy
Correct answer: Mononeuritis multiplex due to rheumatoid vasculitis
Mononeuritis multiplex from rheumatoid vasculitis can cause focal nerve deficits such as wrist drop due to radial nerve involvement.
Question 3: A patient with psoriatic arthritis has predominantly distal interphalangeal joint involvement with nail pitting and 'sausage digit.' Which HLA type is most strongly associated with this condition?
- HLA-B27 (Correct answer)
- HLA-DR4
- HLA-B13
- HLA-Cw6
Correct answer: HLA-B27
HLA-B27 is the most strongly associated HLA antigen in psoriatic arthritis, particularly in patients with axial involvement.
Question 4: A 68-year-old man presents with acute monoarthritis of the first MTP joint, fever, and serum urate of 9.8 mg/dL. Synovial fluid shows negatively birefringent needle-shaped crystals. Which enzyme deficiency leads to the most severe form of gout?
- Adenosine deaminase deficiency
- HGPRT deficiency (Lesch-Nyhan syndrome) (Correct answer)
- Xanthine oxidase deficiency
- Glucose-6-phosphatase deficiency
Correct answer: HGPRT deficiency (Lesch-Nyhan syndrome)
Complete deficiency of HGPRT (hypoxanthine-guanine phosphoribosyltransferase) causes Lesch-Nyhan syndrome with severe hyperuricemia and gout.
Question 5: A 45-year-old woman with Sjögren syndrome presents with purpura, peripheral neuropathy, and elevated serum cryoglobulins. Which complication is she at highest risk for?
- Renal cell carcinoma
- Non-Hodgkin's lymphoma (Correct answer)
- Cervical carcinoma
- Thyroid lymphoma
Correct answer: Non-Hodgkin's lymphoma
Sjögren syndrome carries a 44-fold increased risk of non-Hodgkin's lymphoma, particularly MALT lymphoma of the parotid gland.
Question 6: A 30-year-old male presents with bilateral sacroiliitis, uveitis, and limited lumbar flexion. Schober test measures 2 cm expansion. Which finding on MRI would confirm active sacroiliitis?
- Joint space narrowing
- Bone marrow edema (subchondral) (Correct answer)
- Osteophyte formation
- Periarticular soft tissue calcification
Correct answer: Bone marrow edema (subchondral)
Bone marrow edema on MRI (T2/STIR sequences) is the hallmark of active inflammatory sacroiliitis in ankylosing spondylitis.
Question 7: A 60-year-old woman with RA develops fever, splenomegaly, and severe neutropenia. Bone marrow biopsy shows hypercellularity. Which treatment should be avoided in this patient?
- Rituximab
- Hydroxychloroquine
- Methotrexate (Correct answer)
- Prednisone
Correct answer: Methotrexate
Felty syndrome (RA + splenomegaly + neutropenia) is worsened by methotrexate, which further suppresses neutrophil production.
Internal Medicine Exam Common Rheumatologic Disorders 2
A 35-year-old woman presents with a malar rash, arthralgias, and positive ANA with anti-dsDNA antibodies.
Urinalysis shows proteinuria and RBC casts.
Which class of lupus nephritis carries the worst prognosis if untreated?