Neuroendocrine tumors (NETs) are a heterogeneous group of tumoral lesions originating from diffuse endocrine system cells. They occur mostly in the gastrointestinal system and the lung. Primary NETs of the female reproductive tract are rare. In a widely used classification, primary small cell neuroendocrine carcinomas (SCNECs) and large cell neuroendocrine carcinomas (LCNECs) of the endometrium were included in a subgroup of poorly differentiated neuroendocrine carcinomas. SCNECs of the endometrium are very rare and they are often combined with other epithelial neoplasms. Their myometrial and extrauterine invasions are common during the initial diagnosis due to their aggressive behaviors. In this article, we present a rare case of primary endometrial SCNEC detected within the benign endometrial polyp and without invasion of myometrium and extrauterine tissues in a 70-year-old female patient presenting with postmenopausal bleeding. Histopathologically, the tumor cells showed positive staining with Synaptophysin, the Ki-67 labeling index was 80-90%, the mitotic index was 15/10 per HPF and there was no necrosis and lymphovascular invasion.
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