RECTAL GRANULAR‐CELL TUMOR DIFFICULT TO DISTINGUISH FROM CARCINOID TUMOR

A 60‐year‐old man had a positive fecal occult‐blood test on a medical check‐up. Colonoscopy revealed a yellowish‐white submucosal tumor 8 mm in diameter in the rectum. Endoscopic ultrasonography showed a well‐demarcated mass with a homogeneous, low‐level, internal echo in the second to third layers of the rectal wall. A carcinoid tumor was suspected, and the mass was resected endoscopically. Histopathological examination revealed a granular‐cell tumor. Gastrointestinal granular‐cell tumors rarely arise in the rectum, and the preoperative diagnosis of small lesions is often difficult. In our patient, granular‐cell tumor was difficult to differentially diagnose because the endoscopic and endoscopic ultrasonographic findings closely resembled those of carcinoid tumor. Interestingly, the endoscopic characteristics of the rectal granular‐cell tumor in our patient resembled those of a carcinoid tumor.