A Rare Case of Poorly Differentiated Neuroendocrine Carcinoma of the Descending Colon with Regional Lymph Node Involvement Presenting in a Young Adult Nigerian Male: A Case Report

Malignant colonic neuroendocrine tumours are rare. Even more uncommon is their occurrence in the left colon. They also infrequently occur in males and young adults. We describe a rare case of poorly differentiated neuroendocrine carcinoma of the descending colon in a 32-year-old male who presented with signs of intestinal obstruction. He later had exploratory laparotomy and tumour resection with 5 cm gross tumour margins and Hartman-type colostomy and completed six cycles of Etoposide and Carboplatin combination. He has been tumour- and symptom-free for 36 months. Even though rare, neuroendocrine tumours should be an important differential of all colonic tumours, irrespective of the patient's age and sex, and surgeons should have a high index of suspicion for them. Although they most commonly occur in the right colon (cecum), they can also be found in the descending colon, where they can present with intestinal obstruction. Tumour resection with 5 cm gross tumour margins and Hartman-type colostomy can be handy. Etoposide and Carboplatin combination can improve overall survival in complicated World Health Organization (WHO) stage 3 neuroendocrine carcinoma with regional lymph node involvement, and generally poor prognosis, but without evidence of distant metastasis, and relatively fair performance index. Younger patients with neuroendocrine carcinomas may benefit better from platinum-based chemotherapy.