A renal biopsy from a patient with diabetic nephropathy shows nodular glomerulosclerosis (Kimmelstiel-Wilson lesion). The nodules are composed of:

• A Amyloid fibrils derived from insulin precursors (IAPP)
• B Acellular accumulations of type IV collagen, laminin, and fibronectin (expanded mesangial matrix) ✓
• C Subepithelial immune complex deposits of IgG and C3
• D Organised thrombi recanalised within glomerular capillaries

Explanation

Kimmelstiel-Wilson nodules are the pathognomonic lesion of diabetic nephropathy, representing expanded mesangial matrix (type IV collagen, laminin, fibronectin, and other glycoproteins) deposited in a nodular pattern in the mesangial stalk due to advanced glycation end-product (AGE)-stimulated matrix production and reduced matrix degradation. They are PAS-positive, non-fibrillary, acellular, and located at the periphery of the glomerulus with peripheral capillary loops. IAPP amyloid deposits in islets of Langerhans, not in glomeruli. Immune complex deposits characterise lupus or PSGN nephritis.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.