Abstract
A 58-year-old man presented with swelling in the left inguinal region and loss of appetite, nausea and azotemia with a serum creatinine of 5.2 mg/dL and urine albumin of 1+ and normal size kidneys with no hematuria. His serum creatinine increased to 9 mg/dL over 1 month, his total proteins were 10.8 and serum albumin was 3.3 g/dL, and lymph node excision biopsy showed fragments of lymphoid tissue with interfollicular areas containing sheets of plasma cells and atretic germinal centers. In view of unexplained renal failure, he underwent renal biopsy, which showed interstitial inflammatory infiltrate composed of lymphocytes and rich in plasma cells with storiform fibrosis and a possibility of IgG4-related renal disease was reported. On further evaluation, serum electrophoresis showed no M band. Serum IgG4 levels were 18.2 g/L (0.03-2 g/L). A diagnosis of IgG4-related renal disease was confirmed.