Non-Hodgkin's lymphoma and membranous nephropathy in mixed connective tissue disease.

A 60-year-old woman with a diagnosis of poorly differentiated lymphocytic lymphoma presented with nephrotic syndrome. Her clinical picture and serological studies were consistent with the diagnosis of mixed connective tissue disease (MCTD). Renal biopsy demonstrated the changes of membranous nephropathy by light, immunofluorescence and electron microscopy. Treatment with corticosteroids and cyclophosphamide had no effect on the proteinuria, and she demonstrated progression of renal failure. This patient demonstrates that the lymphadenopathy associated with MCTD may be of a separate malignant origin. The treatment of MCTD may not alter the course of renal disease, and renal failure may ensue in patients with MCTD.