ABSTRACT
Purpose/Background: Colonic large cell type neuroendocrine carcinoma (LCNEC) is a rare type of neuroendocrine tumor with only 13 reported cases in the literature. Due to their rarity, there is currently no standardized management. Hypothesis/Aim: We present a case of colonic LCNEC presenting with obstruction requiring urgent surgical intervention. Methods/Interventions: A 43-year-old male presented to the emergency department with several days of abdominal pain and constipation for 48 hours. Physical exam revealed diffuse abdominal pain. A computed tomography scan of the abdomen and pelvis was concerning for a distal transverse colon mass causing obstruction and multiple hepatic lesions. (Figure 1, A-C). The patient was taken to the operating room for urgent exploration and was found to have a transverse colonic mass was identified just proximal to the splenic flexure. Resection was performed and a side-to-side anastomosis of the right and descending colon was created with a protective loop ileostomy. Liver lesions were biopsied. Pathologic analysis revealed invasion into the peri-colorectal tissue consistent with a T3 lesion. Lymphovascular (LV) and perineural invasion were also present. Seven out 27 total lymph nodes (LN) were positive for cancer and the hepatic nodule was positive for cancer. Histological analysis revealed large cells with prominent nucleoli, abundant cytoplasm, marked pleomorphism, frequent mitosis, and apoptotic bodies consistent with LCNEC (Figure 1, D). Immunohistochemistry showed that the tumor was positive for AE1/1, CK 20, synaptophysin, and chromogranin A. The Ki-67 index was over 95%. Results/Outcome(s): Postoperatively the patient was started on a regimen of cisplatin and etoposide. He was readmitted during his second cycle of chemotherapy with high ileostomy output, E. coli bacteremia and COVID-19. Repeat imaging showed progression of his disease (Figure 1, E). The patient had a precipitous decline in helath and decided to pursue comfort measures. He had a survival time of 3 months after diagnosis. Limitations: The limitation of this study is that it is a single case. Conclusions/Discussion: NECs account for 0.6% of all colorectal cancers with LCNECs responsible for ~0.2% of NECs. At the time of diagnosis, LV invasion, LN spread, and distant metastases are usually present, which coincides with a median survival of 4-16 months. First line treatment for localized colorectal NECs is primary resection. The National Comprehensive Cancer Network (NCCN) guidelines recommend combined cisplatin and etoposide may be appropriate for locally advanced tumors;however, multiple studies have shown to show no improvement in median survival. Our patient presented with obstruction requiring surgical intervention, which extended the patients life by 3 additional months. Further research to define the best course of treatment for advanced colonic LCNECs will be difficult due to the infrequency of the disease. (Figure Presented).