BK Virus-associated Nephropathy in a Patient with T Cell Leukemia/Lymphoma Syndrome.

BK virus-associated nephropathy develops in renal transplant patients with the main manifestation of tubulointerstitial nephritis or ureteral stenosis. Nephrotic syndrome is a rare manifestation of BK virus-associated nephropathy. Here we report a case of a 69-year-old female presenting with nephrotic and nephritic syndrome related to BK virus infection. Kidney biopsy revealed severe acute tubular injury, collapsing glomerulopathy, and focal microangiopathic changes. Four weeks of leflunomide and intravenous immunoglobulin (IVIG) resulted in the recovery of kidney function and improvement of proteinuria.