We report the case of a 53-year-old woman with Sjögren 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 κ and λ light chains. A biopsy diagnosis of Sjögren 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, Sjögren 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 Sjögren 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.