Rapidly Progressive Renal Failure Occurring in the Course of Pyoderma Gangrenosum and IgA (.LAMBDA.) Monoclonal Gammopathy

A 50-year-old man with a 7-year history of an ulcerative rash on the lower extremities had rapidly progressive renal failure. Monoclonal IgA (lambda) was detected in his serum. Kidney biopsy revealed proliferative glomerulonephritis with dominant IgA and C3 deposition, compatible with IgA nephropathy. Immunohistochemical staining with anti-lambda chain was negative and electron microscopic examination revealed deposits in subendothelial and mesangial areas. The findings on the skin biopsy were consistent with that of a pyoderma gangrenosum. The patient was treated with prednisolone pulse therapy followed by oral prednisolone. Renal function gradually and almost completely improved and proteinuria disappeared.