Primary uterine primitive neuroectodermal tumor

Primitive neuroectodermal tumors (PNETs) are rare malignant tumors and extremely rare in uterine corpus. We report a case of primary uterine PNET in Taiwan. A 68-year-old woman presented with vaginal bleeding and abdominal fullness for 2 weeks. Computed tomography revealed one 8.0 cm uterine corpus tumor with carcinomatosis peritonei and ascites. The cancer antigen 125 level was high (280.7 IU/ml). Pathology of endometrial biopsy diagnosed PNET according to the characteristic of small blue round cells with Homer-Wright rosettes and Friend leukemia integration 1 transcription factor (FLI-1) positive. She received dose-dense chemotherapy with paclitaxel and carboplatin, but the response was poor and the PENT metastasized to liver. PNETs belong to small blue round cell tumor group that is difficult to be diagnosed on histopathology. The immunohistochemistry for CD99 and FLI-1 provides high sensitivity and specificity for diagnosis, respectively. No optimal treatment is established due to rarity. The prognosis is poor, usually <3 years survival.