Rare Presentation of a Sub-centimeter Carcinoid Tumor in Rectum With Inactive Liver Metastasis

Abstract

Carcinoid tumors are rare and slow-growing tumors that originate in cells of the neuroendocrine system. Here we discuss a patient with a sub-centimeter rectal carcinoid tumor with inactive liver metastasis. This case highlights the need for awareness of various locations for carcinoid tumor, and given the inactive metastasis, it also prompts a discussion to establish a surveillance strategy in such patients to minimize morbidity and mortality. A 65 year old black male with medical history of Grade III internal hemorrhoids seen on physical exam had a screening colonoscopy done. He had no significant family history and was a former smoker. On colonoscopy, a diminutive sessile polyp at the hepatic flexure, two sessile polyps in the sigmoid colon and a sub-centimeter sessile polyp in the rectum were seen. These were successfully removed during procedure. Biopsy of polyps was unremarkable, except for the rectal polyp, which showed nests of neuroendocrine cells in the lamina propria and submucosa. No mitosis or necrosis was present. Cells were positive for Synaptophysin with few scattered cells positive for Chromogranin. The diagnosis was carcinoid tumor. For staging purposes, a CT Thorax/Abdomen/Pelvis done showed multiple liver lesions. Chromogranin level was 3 nmol/L (ref. 0-5) and total urine 5-Hydroxyindoleacetic acid (5-HIAA) was 4.9 mg/24hrs (ref. 0-14.9). Interestingly, a PET scan did not show any hypermetabolic areas and an MRI Abdomen with liver protocol 3 months later showed stable lesions with no new changes. Follow-up colonoscopy 6 months later was negative for malignancy. Patient's repeat chromogranin levels and 5-HIAA were lower and he denied any symptoms. Patient was placed on a surveillance schedule with imaging every 6 months. Carcinoid tumor is commonly found in the small intestine in 28.5% of cases, while rectal carcinoids comprise only 14% of cases. Furthermore, patients who develop active liver metastasis have a 5-year survival rate of 27%, if not treated. Currently, there are no clear guidelines for management and surveillance to address inactive liver metastasis for carcinoid tumors. While surgical resection is the best treatment for cure in carcinoid tumor, active liver metastasis can be treated with cryoablation, radiofrequency ablation or chemoembolization if surgery is not an option. However, timely treatment is possible if awareness and surveillance guidelines are available, the need for which is highlighted by this case.Figure: Rectal Polyp.Figure: Internal Hemorrhoids.