Metastatic Carcinoid from a Nodule Localized by Complete Double-Balloon Enteroscopy: A Small Lesion with Big Potential

Abstract

Purpose: Carcinoid tumors are rare, slow growing tumors originating from enterochromaffin cells. They generally do not become symptomatic until already metastasized while the primary tumor is still small with the most common site of origin being the small bowel. Double-balloon enteroscopy (DBE) is increasingly becoming an important part of the diagnostic algorithm of primary small bowel neuroendocrine tumor (NET) localization, especially since their surgical excision leads to a better prognosis, even in metastasized NET. A 55-year-old Caucasian woman was diagnosed as having metastatic well-differentiated neuroendocrine tumor lesions of the liver positive for chromogranin and synaptophysin in 2009 per liver biopsy after initially presenting with unexplained fevers and abdominal pain since 2005 but no carcinoid syndrome symptoms. As part of the search for her primary tumor she underwent endoscopic ultrasound of the pancreas and esophagogastroduodenoscopy at our institution. This demonstrated no pancreatic mass but three hepatic hilar and periportal lymph nodes were consistent with benign lymphoid tissue. A MRI of the abdomen and pelvis revealed innumerable arterial enhancing nodules and masses in all segments of the liver consistent with metastatic disease. The largest lesion was in the dome of the liver at the left hepatic lobe, measuring 3.6 cm x 3.5 cm. Additionally, a wireless capsule enteroscopy (WCE) and CT chest were negative. Of note, chromogranin A, serotonin, pancreastatin, pancreatic polypeptide, and gastrin levels were within normal limits. She then underwent a retrograde DBE to the point of maximal insertion, which was the proximal ileum. At the level of the distal ileum there was a 3 mm yellowish nodule removed in one pass. There were no other lesions seen, and the pathology was consistent with a submucosal carcinoid strongly positive for chromogranin, synaptophysin; histochemical stains were positive for Fontana and Grimelius, consistent with mid-gut origin; and the Ki67 proliferation marker was positive in less than 1% of cells. She then underwent an oral DBE to evaluate for other multifocal carcinoid mid gut lesions and the enteroscope was advanced all the way to the cecum with no other lesions identified. An exploratory laparotomy was subsequently performed in order to evaluate for a possible primary tumor; however, despite the small bowel being run in its entirety four times there was neither a macroscopic nor histologic abnormality identified, including in eight regional lymph nodes. This case highlights the metastatic potential of a smaller ileal lesion than has been previously reported in the literature per DBE despite negative imaging, WCE, and exploratory laparotomy.