Gastrointestinal stromal tumor in the rectum

This radiology case report describes an elderly female patient diagnosed with rectal gastrointestinal stromal tumor (GIST). Although these tumors frequently occur in the gastrointestinal tract (~70%), they are relatively rare in the rectum (~0.1%). Computed tomography (CT) scans showed a tumor invading the rectal wall, radiating laterally into the posterior vaginal wall with well-defined focal necrosis around the lesions. Abdomino-perineal resection and posterior vaginectomy followed by histological and immunocytochemical analyses of biopsied tissue verified further the presence of a high grade GIST using primary antibodies directed against CD 117 and CD 34. These data support the hypothesis that GISTs are pathologically related to mutations in receptors for tyrosine kinase pathways, and suggest that elderly individuals might be at risk for developing ectopic forms of GISTs.