Gastrointestinal Stromal Tumor Masquerading as a Spontaneous Rectal Hematoma.

A 78-year-old Caucasian male with a history of atrial fibrillation and anticoagulation with warfarin presented with a change in bowel habits and weight loss. A computed tomography (CT) scan showed a 3.5 cm rectal mass. After biopsy with colonoscopy and endoscopic ultrasonography, the rectal mass was highly suspicious for rectal hematoma. When the rectal mass did not resolve after 1 month of follow-up, surgery showed the patient to have a rectal gastrointestinal stromal tumor. He is being treated with imatinib and follow-up CT scans. This case illustrates the importance of a high level of suspicion for a gastrointestinal stromal tumor when a rectal mass is found.