Liver Metastasis of Synchronous Small Rectal Neuroendocrine Tumors in the Absence of Risk Factors

Abstract

The incidence of rectal neuroendocrine tumors (NETs) has increased worldwide, including in Korea. Rectal NETs are usually single lesions, but synchronous multiple lesions are reported in 2-4.5% of patients. Small rectal NETs (≤ 10 mm) are usually confined to the submucosal layer and rarely give rise to lymph node or distant metastases. Here we describe the case of a 54-year-old woman referred to National Cancer Center for the management of two rectal subepithelial tumors. Because computed tomography revealed a small hepatic nodule suggesting atypical hemangioma rather than metastasis, endoscopic submucosal dissection was performed. However, the size of the nodules increased during follow-up. The pathologic results of a liver biopsy confirmed metastatic NET. This case was unusual in that synchronous small rectal NETs and distant liver metastasis occurred in the absence of any risk factors for metastasis. Thus, patients with rectal NETs should be carefully evaluated, especially for the possibility of metastasis. (Korean J Med 2019;94:281-286)