Large cell neuroendocrine carcinoma arising from uterine endometrium with rapidly progressive course: report of a case and review of literature.

Large cell neuroendocrine carcinoma (LCNEC) of the endometrium is a rare and highly malignant neoplasm with no characteristic findings in terms of clinical manifestations, diagnostic imaging, or pathology, and thus, the definitive preoperative diagnosis of LCNEC is difficult. A 61-year-old postmenopausal woman presented with low abdominal pain and a rapidly growing uterine mass without postmenopausal bleeding. Magnetic resonance imaging of the pelvis revealed an enlarged uterus with a 7.5 cm mass. Intraoperative frozen examination revealed a malignant tumor, and accordingly, cytoreductive surgery was performed. Microscopically, the tumor showed extensive necrosis, hemorrhage, and an organoid nesting pattern of large cells. Immunohistochemistry revealed tumor cells were diffusely positive for the neuroendocrine markers CD56 and synaptophysin. Thus the tumor was diagnosed as LCNEC of endometrium. Postoperatively, the disease pursued a progressive course and relapsed even after repeated multiple chemotherapy courses. The patient succumbed to the disease 23 months after surgery. We present a case of LCNEC of the endometrium with a high Ki-67 index that exhibited a rapidly progressive course. LCNEC should be considered when a rapidly growing uterine tumor is detected.