Sjogren Syndrome and Cryoglobulinemic Glomerulonephritis

We report the case of a 53-year-old woman with Sjogren syndrome and cryoglobulinemia. The patient presented with nephrotic syndrome, hematuria, and reduced estimated glomerular filtration rate. The kidney biopsy revealed diffuse endocapillary proliferation and leukocyte exudation with focal intraluminal hyaline thrombi, prominent tubulointerstitial inflammation, and vasculitis. Diffuse granular mesangial and segmental to global capillary wall staining was observed on immunofluorescence with antisera to C3 and immunoglobulin M (IgM), with less intense staining indicative of IgG and kappa and lambda light chains. A biopsy diagnosis of Sjogren syndrome-related cryoglobulinemic membranoproliferative glomerulonephritis and vasculitis was rendered. Subsequent investigations revealed the presence of circulating type II cryoglobulins with cryocrit of 9%. Although rare, Sjogren syndrome is the most common cause of non-hepatitis C virus-related mixed cryoglobulinemia. We discuss the possible pathogenic mechanisms involved in the development of mixed cryoglobulinemia and its evolution to lymphoma, as best described in the setting of hepatitis C virus infection. Although the specific antigen involved is unknown, it is likely that the mixed cryoglobulinemia in Sjogren syndrome is triggered by the long-term B-cell stimulation, resulting in clonal proliferation of B cells. Additional chromosomal aberrations and cytokine milieu alterations, as seen in hepatitis C virus infection, may result in prolonged B-cell survival and progression to non-Hodgkin lymphoma. (C) 2015 by the National Kidney Foundation, Inc.