RESUMEN
A 71-year-old man began feeling a lower abdominal pain at bowel movement about one year ago. He was found to have a pelvic tumor during a health examination and referred to our hospital for further evaluation. CT and MRI scans demonstrated a giant pelvic tumor, 10 cm in size, which compressed the rectum. The likely preoperative diagnosis was leiomyosarcoma from the rectum or neurilemoma. To regulate intraoperative hemorrhaging and to reduce the tumor size, angiography was performed at two days before the operation and embolization of the tumor vessels was done. He had a tumor resection and a low anterior resection of the rectum and a transient colostomy of the ascending colon without blood transfusion. The resected tumor was covered with thin yellowish-white capsule with smooth surface, elastic hard on palpation, and was measured 10.5 × 9 × 10.5 cm, and weighted 320 g. The pathological diagnosis was neurilemoma (schwannoma) consisting both Antoni type A and Antoni type B sections.