Multiple large cell neuroendocrine carcinomas in the rectum and descending colon presented with liver metastasis: A case report

Colorectal large cell neuroendocrine carcinoma (LCNEC) is rare and multiple LCNECs have not been previously reported. We encountered a case of multiple LCNECs in the rectum and the descending colon. A 66-year-old man presented with anal pain. Colonoscopy showed an ulcerated infiltrating tumor in the rectum, and 0.5 cm of erosion in the descending colon. A biopsy revealed LCNEC in both regions. Abdominal computed tomography revealed irregularly enhanced wall thickening at the rectum and hepatic metastases. Due to the diagnosis of LCNEC, laparoscopic abdominoperineal resection of the rectum was performed. Histopathological examination showed a poorly differentiated, LCNEC in both regions. Immunohistochemical examination demonstrated that the tumor cells were positive for chromogranin and synaptophysin. LCNEC was confirmed, and systemic chemotherapy with cisplatin/irinotecan was initiated. To our knowledge, this is the first case report that describes multiple LCNECs in the rectum and descending colon.