Large Cell Neuroendocrine Carcinoma Presenting as Adult Intussusception.

Large cell neuroendocrine carcinoma (LCNEC) is an extremely rare malignant tumor of the colon, presenting with more severe clinical outcomes in comparison to colonic adenocarcinoma. There are very few reported cases in the literature. We hereby add our voice to the incidence of this disease by presenting the first report of a patient with ileocolic intussusception secondary to a large cell neuroendocrine cancer of the cecum. The patient was a 48-year-old woman who presented with acute onset of generalized abdominal pain and leukocytosis. CT scan revealed an ileocecal intussusception and multiple liver metastases suggestive of a malignant bowel lesion. She underwent emergency surgery, and an extended right hemicolectomy with ileo-transverse anastomosis was performed. Histology of the resected lesion revealed large cell neuroendocrine carcinoma of the cecum with invasion through the muscularis propria into peri colorectal tissues. The tumor retained mismatch repair (MMR) proteins with low potential for microsatellite instability (MSI). With a clinical diagnosis of stage IV LCNEC, the patient began platinum doublet chemotherapy with carboplatin and etoposide; however, her disease progressed, and the patient expired within a few months after her diagnosis. Clinical diagnosis of adult intussusception should prompt clinicians to rule out malignant etiology. This patient had a large cell neuroendocrine carcinoma of the colon, a rare and extremely aggressive malignancy. Patients with LCNEC will benefit from a multidisciplinary approach to treatment.