Primary pure small cell neuroendocrine carcinoma of the endometrium: a case report

Small cell carcinoma is a highly aggressive neuroendocrine malignancy that most commonly arises in the lungs, gastrointestinal tract, or pancreas. Primary small cell neuroendocrine carcinoma of the endometrium is exceedingly rare, and its clinical characteristics, diagnostic criteria, and optimal treatment strategies remain poorly defined.

We report the case of a 74-year-old postmenopausal Chinese woman (gravida 4, para 4) who presented with a 20-day history of irregular vaginal bleeding. Transvaginal pelvic ultrasound performed at an outside institution 1 week prior to admission revealed an intrauterine mass with internal vascularity, suggestive of an endometrial neoplasm. Pelvic magnetic resonance imaging demonstrated an intrauterine mass invading the deep myometrium, without definite evidence of extrauterine metastasis. Serum tumor markers were within or near normal ranges. Diagnostic curettage revealed a malignant neoplasm, and immunohistochemistry confirmed a diagnosis of small cell neuroendocrine carcinoma of the endometrium. The patient subsequently underwent laparoscopic extrafascial total hysterectomy with bilateral salpingo-oophorectomy and pelvic and para-aortic lymphadenectomy. Histopathological examination confirmed a 3.0 cm × 2.0 cm × 2.5 cm small cell neuroendocrine carcinoma of the endometrium with invasion of more than half of the myometrium and diffuse lymphovascular space invasion but without lymph node metastasis. According to the 2009 International Federation of Gynecology and Obstetrics (FIGO) staging system, the tumor was classified as stage IB. Given the aggressive histological features, the patient received six cycles of adjuvant chemotherapy with etoposide and cisplatin. To date, corresponding to 18 months after completion of chemotherapy, no evidence of disease recurrence or metastasis has been observed.

Primary pure small cell neuroendocrine carcinoma of the endometrium is an exceptionally rare and highly malignant neoplasm associated with an unfavorable prognosis. Accurate diagnosis relies on histopathological and immunohistochemical evaluation. In this single-case observation, comprehensive surgical staging followed by platinum-based chemotherapy was administered. However, owing to the limited follow-up duration and the absence of adjuvant radiotherapy, definitive conclusions regarding treatment efficacy cannot be drawn. Larger case series and longer-term follow-up are required to establish optimal management strategies for this rare tumor.