In multiple myeloma, M-protein is detected in serum. The pathological basis for the renal lesion known as 'myeloma cast nephropathy' (myeloma kidney) involves:
- A Deposition of intact immunoglobulin in glomerular mesangium
- B Precipitation of free light chains (Bence Jones proteins) with Tamm-Horsfall protein in distal tubules ✓
- C Amyloid AL deposits in glomerular capillaries
- D Direct infiltration of tubules by plasma cells
Correct answer: B. Precipitation of free light chains (Bence Jones proteins) with Tamm-Horsfall protein in distal tubules
Explanation
Myeloma cast nephropathy results from the filtration of free immunoglobulin light chains (Bence Jones proteins) which co-precipitate with the normal tubular protein Tamm-Horsfall (uromodulin) in the distal tubules and collecting ducts, forming obstructive casts with a characteristic fractured appearance and surrounding giant cell reaction. This is the most common renal lesion in myeloma. AL amyloidosis is a separate entity causing nephrotic syndrome; mesangial deposits characterize IgA nephropathy.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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