A 70-year-old female presents with 8 grams of proteinuria and a creatinine of 2.1. She relays that she has noticed a gradual increase in swelling over the last 6 months. She denies NSAID use and any new exposures.

What is the best diagnosis?

A. Cryoglobulinemia
B. IgA Nephropathy
C. Post-infectious Glomerulonephritis
D. Thrombotic Microangiopathy

The best answer is A – cryoglobulinemia.
The photographs show a membranoproliferative glomerulonephritis with numerous hyaline thrombi. The hyaline thrombi stain for IgM, IgA, kappa, and lambda. The best diagnosis is cryoglobulinemia. IgA nephropathy is a consideration, but IgA nephropathy typically has mesangial staining and usually no hyaline thrombi. Post-infectious glomerulonephritis is an exudative glomerulonephritis which has subepithelial humps by EM, but no hyaline thrombi. A thrombotic microangiopathy displays a different glomerular pattern of injury and has acellular closure of capillary walls, mesangiolysis, and no hyaline thrombi.