Poorly Differentiated Large Cell Neuroendocrine Carcinoma of the Transverse Colon: Case Report

Introduction: Neuroendocrine carcinomas (NECs) of the colon and rectum are extremely rare malignant subtypes of neuroendocrine tumors, with a reported incidence of 0.1% to 3.9% of all colorectal malignancies. Large cell neuroendocrine carcinomas of the colon (LCNECs) are even rarer, aggressive in nature and have a poor prognosis due to their tendency to early metastasis. Case report: Large cell neuroendocrine carcinoma in the transverse colon with liver metastasis of a 66 years- old male patient, who reported cramping abdominal pain for two months, weight loss of 12 kilos and melena during this period. Abdominal tomography showing circumferential parietal thickening with an infiltrative and stenosing appearance in the transverse colon on the right and multiple hypovascular solid hepatic nodules. Pathology of the lesion compatible with poorly differentiated carcinoma and liver metastases was metastatic adenocarcinoma. Material from the colon biopsy and liver lesions were sent for immunohistochemical studies confirming the diagnosis of high-grade neuroendocrine carcinoma. Conclusion: Early detection can offer a better prognosis for other patients and correct diagnosis is of great importance, as they are often misdiagnosed as adenocarcinoma or another malignant tumor on first imaging or histological study.