eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2022-09-12 10 9 224 226 10.12691/ajmcr-10-9-3 AJMCR20221093 article Oadi N. Shrateh oadi.shrateh@students.alquds.edu 1 Ali N. Obeidat 1 Maysam Hamarsheh 2 Mohand Abulihya 3 Mashhour Naasan 3 Faculty of Medicine, Al-Quds University, Jerusalem, Palestine Department of Obstetrics and Gynecology, Al-Istishari Arab Hospital, Ramallah, Palestine Department of pathology, Al-Istishari Arab Hospital, Ramallah, Palestine Introduction: Pure large cell neuroendocrine carcinoma (LCNEC) of the endometrium is a rare and inadequately researched gynecologic malignancy with an aggressive course. Our knowledge of pure LCNEC of the endometrium is restricted to case reports. Herein, we describe a very rare case of pure LCNEC of the endometrium. Case presentation: A 70-year-old female presented with post-menopausal uterine bleeding and abdomino-pelvic pain. A sufficient sample endometrial biopsy showed benign endometrial tissue. We performed total abdominal hysterectomy with bilateral salpingo-oophorectomy and the final histopathology and immunohistochemistry established the diagnosis of a pure type of LCNEC of the endometrium (positive for Synaptophysin, CD56, focal Pan-CK, P53, and OCT3/4). Conclusion: A pure LCNEC of the endometrium is extremely uncommon and is often mistaken for a poorly differentiated endometrial carcinoma. Pure LCNEC of the endometrium is a difficult diagnosis to establish. That is why, high clinical suspicion index is required along with performing histological and immunohistochemical testing. Although rare, it is very important to include pure LCNEC of the endometrium in the differential diagnosis of abnormal uterine bleeding and/or abdomino-pelvic pain, especially in the postmenopausal sitting. http://pubs.sciepub.com/ajmcr/10/9/3/ajmcr-10-9-3.pdf pure large cell neuroendocrine carcinoma endometrial cancer abnormal uterine bleeding Synaptophysin CD56