Abstract: Primitive neuroectodermal tumor (PNET) is divided into central and peripheral types. Peripheral PNET belongs to the family of Ewing′s sarcoma. Its occurrence is due to abnormal gene regulation, thus the primitive stem cells differentiate into different stages of neural epithelialcells which is similar to pediatric central nervous system tumors morphologically. The histological and clinical biological behavior of the peripheral PNET are similar to extra-osteous Ewing′s sarcoma. Ovarian primary PNET is peripheral PNET, belonging to the ovarian monoderm teratoma, which is extremely rare and metastasizes early, relapses easily with poor prognosis. The clinical manifestation is lack of specificity, and patients always show with chief complaints with abdominal pain, abdominal distention and pelvic mass. The pathology is the gold standard for diagnosis. There is still no exact guideline for treatment, and most articles regarding this neoplasm have been case reports because of its rarity. Only seventeen cases of ovarian primary PNET had been reported in the English language literature between 1975 and 2017. And we reported four additional cases treated at the Peking Union Medical College Hospital to depict the clinical behavior, treatment strategies and prognosis of the ovarian primary PNET.

Key words:  Ovaｒｙ, Ｎｅｕｒｏｅｃｔｏｄｅｒｍａｌ ｔｕｍｏｒ, ｐｒｉｍｉｔｉｖｅ, Ｄｒｕｇ ｔｈｅｒａｐｙ, ｃｏｍｂｉｎａｔｉｏｎ, Ｒａｄｉｏｔｈｅｒａｐｙ, Ｔａｒｇｅｔ ｔｒｅａｔｍｅｎｔ, Prognｏｓｉｓ, Ｃａｓｅ ｒｅｐｏrts