Type II Cryoglobulinemic Membranoproliferative Glomerulonephritis Caused by Mucosa-associated Lymphoid Tissue Lymphoma

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A 67-year-old man complained of lower limb edema with a purpuric skin rash. Laboratory tests revealed proteinuria, elevated serum creatinine levels, and low serum albumin levels. The patient was also positive for cryoglobulin in serum, immunoglobulin (Ig) M gammopathy, hypocomplementemia, and rheumatoid factor. He was negative for anti-hepatitis C virus antibodies. A pathological analysis of the renal tissue revealed membranoproliferative glomerulonephritis, common histological features of cryoglobulinemic vasculitis (CV), and mucosa-associated lymphoid tissue lymphoma invasion. Although hematologic malignancy is a rare cause of type II CV, these clinical findings suggest that mucosa-associated lymphoid tissue lymphoma (MALT) lymphoma may have been the cause in the present case.