Neoplasia USMLE Step 1 Practice Question
A 63-year-old man presents with progressive fatigue, nephrotic-range proteinuria (8.5 g/day), and bilateral foot numbness. Vital signs show BP 138/82, HR 88, RR 16, Temp 37.2°C, SpO2 98% on room air. Serum protein electrophoresis reveals an IgG monoclonal spike. Bone marrow biopsy demonstrates 35% clonal plasma cells. Renal biopsy shows amorphous eosinophilic extracellular deposits under light microscopy; Congo red staining is negative. Which protein most likely comprises these deposits?
Answer choices
- AImmunoglobulin light chain derived fibrilsCorrect answer
- BCalcitonin derived fibrils
- CSerum amyloid A derived fibrils
- DBeta amyloid precursor protein derived fibrils
- ETransthyretin derived fibrils
- FImmunoglobulin heavy chain derived fibrils
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