An Incidental Finding of Rectal Carcinoid Tumor

Abstract

Adenocarcinoma is the most common malignancy found in the rectum. However, the incidence of rectal carcinoid has been rising after implementation of screening colonoscopy. The rectum is the second most common anatomic site for carcinoid tumor. Embryologically, rectal carcinoids are hindgut tumors which are non secretory. Hence, they rarely present with carcinoid syndrome even in patients with metastatic disease. A recent systematic review of rectal carcinoid by McDermott et.al was unable to perform a metaanalysis on optimal treatment strategies for localized and widespread disease due to the wide variety of data recorded from various sources. Our aim is to make physicians aware that the rectal carcinoid is becoming a common diagnosis thus clinicians should have current knowledge of classification, management and treatment options available. A 62-year-old African American male with a significant past medical history of hypertension and tobacco abuse presented to the gastrointestinal (GI) lab for colorectal cancer screening colonoscopy. Patient had no specific GI complaints and a 10-point review of symptoms was unremarkable except for decreased exercise tolerance. Physical examination was unremarkable including digital rectal exam. During colonoscopy, a 7-10 mm firm polypoid submucosal lesion was noted in distal rectum and was resected using an electrocautery snare and ERBE endocut current. Histologic evaluation of the resected polyp demonstrated a well-differentiated neuroendocrine neoplasm that stained positive for chromogramin, synaptophysin, and Ki-67 proliferation marker. Patient underwent repeat colonoscopy about a month later. Biopsy obtained from previous polypectomy site was negative for carcinoid tumor cells. The rectal carcinoid classification, management and treatment options have been defined based on the size and aggressiveness of the lesion. As there is no defined TNM system classification, there is no homogenous data available yet on how to manage rectal carcinoid. Treatment strategy is based on tumor size, radiologic testing and surveillance examination including use of rectal EUS.Figure 1