Rectal Neuroendocrine Tumor (G1) with Liver Metastasis: A Case Report

 Neuroendocrine carcinoma is a rare tumor and arises from cells dispersed in the neuroendocrine system.

 In this study, we report a 62-year-old man who was presented with a chief complaint of constipation in 2019 at Firoozgar Hospital in Tehran. The patient had no family history of cancer but noted a weight loss of 15 to 20 kg over the past 8 months.

 According to the colonoscopy, there was a polypoid lesion about 10 to 15 mm in the rectum, and biopsy was done for histological studies. In the present study, a metastatic rectal neuroendocrine tumor was detected in the liver.Microscopic studies of the mass revealed a well-differentiated neuroendocrine carcinoma. Immunohistochemical (IHC) staining was positive for Chromogranin, Pan-Cytokranine, and Ki-67 and negative for Synaptophysin, Hepar, TTFI, PAX8, and CDX2. After performing diagnostic procedures for excisional rectal biopsy, Transanal Minimally Invasive Surgery (TAMIS) was performed. After a few days, the patient was discharged with a good general condition and stable vital signs.

 Although neuroendocrine tumors of the rectum relatively slow growth, they are malignant and can metastasize to other areas. In general, the prognosis of patients with metastatic disease is poor and information about the specific treatment of these patients is limited