A hemodialysis patient with primary extra-gastrointestinal stromal tumor: favorable outcome with imatinib mesylate.

Extra-gastrointestinal stromal tumors (EGISTs) are rare. We describe a 69-year-old man with a 9-year history of hemodialysis. This patient was diagnosed as having peritoneal tumors measuring over 10 cm in length. Histologically, the tumors were composed of monomorphic spindle cells. The number of mitotic figures was 5 per 50 high-power fields. Immunohistochemical analysis revealed strong positivity for c-KIT and MIB-1. He was treated with imatinib mesylate with no recurrences 20 months later. We present this first case of EGIST in a hemodialysis patient in which imatinib mesylate had a favorable outcome and also discuss the rarity of this case.