A 35-year-old IV drug user develops focal segmental glomerulosclerosis (FSGS). The pattern on light microscopy shows scarring and hyalinosis affecting only PART of the glomerulus and only SOME glomeruli. What is the mechanism by which HIV causes FSGS (HIV-associated nephropathy)?
- A Immune complex deposition with complement activation
- B Direct infection of podocytes by HIV causing collapsing FSGS with focal microcystic tubular dilatation ✓
- C Thrombotic microangiopathy from endothelial injury
- D Membranous nephropathy from anti-PLA2R antibodies
Correct answer: B. Direct infection of podocytes by HIV causing collapsing FSGS with focal microcystic tubular dilatation
Explanation
HIV-associated nephropathy (HIVAN) is caused by direct HIV infection of podocytes and tubular epithelial cells, driven by HIV genes nef and vpr. The result is the collapsing variant of FSGS — the most severe form characterized by global glomerular collapse with overlying podocyte hyperplasia, plus a distinctive microcystic tubular dilatation containing proteinaceous casts. It predominantly affects patients of African descent (APOL1 risk alleles). This is distinct from immune-complex nephropathies; anti-PLA2R antibodies cause primary membranous nephropathy.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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