Kidney biopsy reveals metastatic adenocarcinoma of the appendix simulating nephrotic syndrome.

Membranous glomerulonephritis (MGN) is among the most common causes of nephrotic syndrome in adults. The malignancy in presumed tumor-induced MGN has usually been diagnosed at the time the proteinuria is discovered. Here we report a 57-year-old male patient with a history of refractory pyuria and nephrotic syndrome. The kidney biopsy confirmed the diagnosis of not only MGN, but also metastasis of appendix adenocarcinoma. To our knowledge this is the first case report diagnosed as a metastatic malignancy from a kidney biopsy which no other imaging techniques were able to display.