Membranous glomerulonephritis associated with testicular seminoma.

Proteinuria, often nephrotic in range, is a recognized paraneoplastic syndrome of solid tumours, with membranous glomerulonephritis (MGN) the most common histopathological lesion seen on renal biopsy. A 56-year-old male was found to have proteinuria on routine medical examination. History, physical and serological evaluation failed to reveal an aetiology and subsequent renal biopsy showed MGN, presumed to be idiopathic. Prednisone therapy was begun but this proteinuria did not resolve (> 1 g 24 h-1). Eleven months later the patient discovered a testicular mass which was found to be a stage I seminoma upon excision and metastatic evaluation. His proteinuria rapidly normalized after orchectomy and regional lymph node radiotherapy. This is the first known case of MGN associated with testicular seminoma.