Rectal leiomyosarcoma diagnosed by endoscopic ultrasonography

A 67 year-old man was admitted to the Tainan Municipal Hospital due to a protruding mass, usually noted during defecation. Digital examination revealed a single, smooth, large mass over the rectum, occupying almost the entire lumen. Colonoscopy, barium enema, and computed tomography (CT) demonstrated a submucosal tumor of the rectum. Endoscopic ultrasound (EUS) study showed that the tumor originated from the muscle layer. Based on the size, margin and echogenicity of the mass, a malignant neoplasm, probably leiomyosarcoma, was diagnosed. Post-operative histologic examination confirmed that the resected tumor was leiomyosarcoma. Existing ancillary procedures like colonoscopy, abdominal CT, magnetic resonance image (MRI), and barium enema are neither reliable nor accurate in locating which layer the lesion originates. Colonoscopic biopsy is disappointing since submucosal tumor is usually inaccessible. EUS study can provide us with a more distinct image with regards to tumor origin, size, margin and echogenicity. This report emphasizes the important role of EUS in the pre-operative diagnosis of submucosal tumors of the rectum. Furthermore, this tool can aid the surgeons whether wide excision or an abdomino-perineal resection should be performed.