Von Recklinghausen's disease associated with malignant peripheral nerve sheath thmor presenting with constipation and urinary retention: a case report and review of the literature.

A malignant peripheral nerve sheath tumor (MPNST) is a rare neoplasm arising from peripheral nerve sheaths. We herein report the first case of MPNST originating from the left gluteal muscle region, diffusely extending into the adjacent small pelvis and perineum. The patient was a 25-year-old man who presented with symptoms of progressive constipation and urinary retention associated with weight loss. The patient had a family history of neurofibromatosis type 1. Physical examination showed numerous cafe-au-lait spots and sessile cutaneous neurofibromas. A computed tomography scan revealed a giant tumor which displaced the bladder and segments of the intestine. The histopathological diagnosis was MPNST. The mass was considered inoperable and palliative colostomy was performed. The patient declined chemotherapy and radiation therapy and died 2 months later.