Abstract
Large-cell neuroendocrine carcinoma (LCNEC) of the endometrium is an extremely rare, high-grade malignant tumor. We herein report a case of a rapidly growing LCNEC arising in the endometrium. A 52-year-old woman was referred to Toyooka Hospital (Tooyoka, Japan) due to genital bleeding in February 2016. There had been no abnormalities on a regular gynecological and physical examination 3 months prior to the consultation. Imaging (computed tomography and magnetic resonance imaging) and a pelvic examination revealed a tumor sized 16.9×8.4×7.8 mm occupying the intrauterine cavity and extending into the vaginal cavity. Multiple metastatic pelvic and paraaortic lymph nodes were also identified. Continuous bleeding from the tumor was observed, and a blood examination revealed anemia, which was likely due to that bleeding. Biopsy of the tumor was performed, and large atypical cells were identified. The tumor cells were negative for cytokeratin AE1/AE3 and chromogranin A, but positive for CD56 and synaptophysin. There was also an abundance of Ki-67-positive cells in the tumor, altogether suggesting that the tumor was an LCNEC. The patient succumbed to the disease 36 days after the first consultation. Based on the findings of the present case and previously published cases, LCNECs arising in the endometrium may progress rapidly and are associated with an unfavourable outcome. LCNEC should be included in the differential diagnosis in cases of rapidly growing tumors of the uterine corpus.