Rapidly progressing large-cell neuroendocrine carcinoma arising from the uterine corpus: A case report and review of the literature.

Large-cell neuroendocrine carcinoma (LCNEC) is a high-grade neuroendocrine tumor. LCNECs arising from the genital organs are highly malignant and rare, with <20 cases of LCNEC developing from the uterine endometrium reported to date. We herein present the case of a patient with LCNEC of the endometrium. The patient was a 52-year-old woman, who exhibited lower abdominal pain and rapid uterine enlargement during outpatient treatment for uterine myoma. The endometrial biopsy suggested a diagnosis of poorly differentiated carcinoma or carcinosarcoma. Based on magnetic resonance imaging and positron emission tomography/computed tomography, endometrial stromal sarcoma was suspected. The serum lactate dehydrogenase level was abnormally high. Due to the suspicion of stage IIIC malignant tumor of the uterine corpus, surgery was performed. The pathological diagnosis was stage IIIC2 LCNEC of the endometrium. Recurrence occurred in the vaginal stump, and concurrent chemoradiotherapy (CCRT) was initiated 1 month after the surgery. The residual lesions markedly shrank, but metastasis to the upper abdominal region and cervix subsequently developed. CCRT was attempted, but the associated adverse effects were severe and was switched to palliative treatment. The patient eventually succumbed to the disease 309 days after surgery.