[1671] Cryoglobulinemic Nephropathy: Spectrum of Clinical and Immunomorphologic Manifestations

Guillermo A Herrera, Elba A Turbat-Herrera. Nephrocor, Orlando, FL

Background: Thc clinical and pathologic manifestations of cryoglobulinemic nephropathy (CN) are heterogeneous. This is in part due to the fact that this disease is cyclical resulting in variable concentrations of cryoglobulins in the serum affecting renal patterns of damage. Light and immunomorphologic manifesations in renal biopsies are quite variable and only reported in small series. This is the largest series of CN cases in the literature.
Design: 3300 renal biopsies from 2 institutions over a period of 5 years were reviewed to identify cases of CN. Twenty six cases from 25 patients were found. Light, immunofluorescence, and ultrastructural findings were critically analyzed to obtain a comprehensive view of the spectrum of clinical and immunomorphologic renal manifestations.
Results: 0.8% of all renal biopsies were diagnosed with CN. There were 17 male and 8 female patients. Their age ranged from 27 to 81 and the mean age was 54 years. Clinical manifestations were quite varied with acute renal failure (35% of all cases), proteinuria (some associated with nephrotic syndrome), and arthritis being the most common. Associated renal diseases were present in most cases with hepatitis C being the most common (in 46% of the patients), followed by systemic lupus erythematosus, and monoclonal gammopathy of unknown significance (MGUS).
The most common light microscopic appearance was that of a membranoproliferative glomerulonphritis (50% of the cases0, followed by proliferative/exudative variants (12%). Capillary thrombi were seen in 65% of the cases, representing the most constant finding by light microscopy.
Immunofluorescence patterns, though all granular, were also variable. "Full" house fluorescence was present in 40% of the cases. C3 staining was the most constant finding (in more than 75% of the cases).
Electron microscopy showed variable ultrastructural appearances of cryoglobulins including annular, curved, and paired short microtubular structures. No fingerprints, fibrillary, or crystalloid forms were seen.
Conclusions: The immunomorphologic patterns associated with CN are quite heterogeneous. The most common light microscopic finding was that of capillary thrombi associated with variable proliferative/exudative changes. Differential diagnosis included a variety of proliferative/exudative glomerulonephritis. A final, unequivocal diagnosis was only possible ultrastructurally by finding diagnostic substructures in the electron dense deposits, best detected in the capillary thrombi when present and, if absent, in subendothelial deposits.
Category: Kidney (does not include tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 296, Wednesday Afternoon

 

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