Myxoid perineurioma in a transplanted kidney.

Perineuriomas are rare, benign peripheral nerve sheath tumors, most commonly found in the extremities and trunks. A handful of cases have been reported to arise from the retroperitoneum and in kidneys. To our knowledge, this is the first reported case of a myxoid perineurioma arising from a transplanted kidney. The patient is a 40-year-old Chinese male with end-stage kidney disease secondary to chronic sclerosing glomerulonephritis. He has a nonfunctioning renal graft in his right iliac fossa and a functioning graft in the left. Routine imaging found a mass in the nonfunctioning graft which was increasing in size. He underwent graft nephrectomy and histology revealed a myxoid perineurioma with no atypical features or malignancy.