An unusual case of membranous nephropathy associated with an ovarian tumor.

Secondary membranous nephropathy (MN) associated with malignancy is not uncommon in adults, but it is rare in children. We report a 6-year-old girl who developed nephrotic-range proteinuria following diagnosis of a Sertoli-Leydig ovarian tumor. A renal biopsy was performed, which led to the diagnosis of MN. The patient maintained normal renal function and gradually showed improvement in proteinuria over several months without the use of corticosteroids or angiotensin-converting enzyme inhibitors. Our case highlights the importance of performing screening urinalyses in children with tumors to recognize the presence of clinically significant, but potentially asymptomatic kidney disease.