The clinicopathologic features of cryoglobulinemic nephropathy.

Renal biopsy specimens from eight patients with cryoglobulinemic nephropathy were examined by light, electron, and immunofluorescence microscopy. The light microscopic features were not diagnostic. Characteristic ultrastructural findings were observed in all except one specimen and consisted of glomerular electron-dense deposits, which had a coarse, granular appearance at low-power magnifications and revealed tubular, annular and in a few cases, also fibrillar structures at high-power magnifications. Subendothelial deposits were a constant finding. The presence of intravascular thrombi (deposits), osmiophilic bodies, and crystals within the cytoplasm of the glomerular cells are also helpful for the diagnosis of this entity. Because of these specific findings, cryoglobulinemic nephropathy should be recognized as a clinicopathologic entity.