Gastrointestinal Stromal Tumor of the Rectum Diagnosed by Prostate Needle Biopsy: Report of a Case

A 52-year-old man was referred to our institution with the presentation of rectal bleeding, and change in caliber of his stools. On rectal examination a solid mass was palpated in the prostate area. Transrectal needle biopsy and cytology showed a gastrointestinal stromal tumor. Subsequent rectal ultrasound demonstrated a hypoechogenic lesion that appeared to be growing out of the muscularis propria of the anterior rectal wall. Magnetic resonance imaging showed a well demarcated mass measuring 9 cm in diameter, which occupied the cavity of the lesser pelvis. A low anterior rectal resection with protective ileostomy was performed. The macroscopic findings showed the tumor measuring 9 cm, growing from the anterior wall of the rectum. Histological examination of the excised specimen revealed up to 5 mitoses per 50 high-power fields. The postoperative course was uneventful and ileostomy was closed after six weeks. Magnetic resonance imaging on follow-up five years postoperatively showed no signs of recurrence.