Single Rectal Neuroendocrine Tumor Associated with Multiple Endocrine Cell Micronests: A Case Report

Although a few reports of neuroendocrine tumor (NET) in the stomach or appendix with surrounding micronests have been published, cases of rectal NET are rare. We herein report a unique case of a patient with single rectal NET treated endoscopically. A pathological examination revealed multiple endocrine cell micronests (ECMs) in the submucosal layer around the main NET lesion. Neither lymph node metastasis nor distant metastasis in computed tomography was observed six years after the treatment. Because case reports of multiple ECM are very rare, the significance of malignancy is unclear. It therefore appears to be necessary to accumulate similar cases.