Abstract
An 88-year-old man visited us with the chief complaint of anal pain. A gastrografin enema study showed circular stenosis in the lower rectum. During colonoscopy, the scope could not be introduced past the severely stenotic lesion. No definitive diagnosis could be made by endoscopic biopsy. A trans-anal incisional biopsy during surgery revealed the diagnosis of poorly differentiated adenocarcinoma or neuroendocrine cell carcinoma. Therefore, we performed laparoscopic rectal amputation and laparoscopic right hemicolectomy for rectal cancer and ascending colon cancer. The pathological diagnosis was Rb, type 4, 45×35 mm, neuroendocrine carcinoma, pT3 (A), pN1 and A, type 2, 75×65 mm, tub1+muc, pT3 (SS), pN0. Immunohistochemistry revealed positive staining for proGRP, which is relatively specific for rectal cancer. We report a very rare case of lower rectal cancer that showed the characteristics of a diffuse infiltrative neuroendocrine cell carcinoma.
