Primitive neuroectodermal tumor of the corpus uteri

Primitive neuroectodermal tumor (PNET) of the corpus uteri is an extremely rare and aggressive malignant neoplasm arising within the body of the uterus. Also referred to as central-type PNET or uterine PNET, this tumor belongs to the family of small round blue cell tumors that are thought to originate from neuroectodermal progenitor cells. While PNETs more commonly occur in the central nervous system and bones (Ewing sarcoma family), their occurrence in the uterine corpus is exceptionally unusual. The tumor primarily affects the female reproductive system, specifically the endometrium and myometrium, and can present with abnormal uterine bleeding, pelvic pain, and a rapidly enlarging uterine mass. Due to its aggressive nature, the tumor frequently metastasizes to distant sites including the lungs, liver, and peritoneum. Histologically, the tumor is characterized by sheets of small, round, undifferentiated cells with high nuclear-to-cytoplasmic ratios and frequent mitotic figures. Immunohistochemical staining typically shows positivity for CD99 (MIC2), neuron-specific enolase (NSE), synaptophysin, and other neuroectodermal markers, which help distinguish it from other uterine malignancies such as endometrial stromal sarcoma, carcinosarcoma, and undifferentiated uterine sarcoma. Molecular analysis may reveal EWSR1 gene rearrangements in some cases, supporting the diagnosis. Given the rarity of this tumor, no standardized treatment protocol exists. Management typically involves a multimodal approach including radical hysterectomy with bilateral salpingo-oophorectomy, often followed by adjuvant chemotherapy regimens similar to those used for Ewing sarcoma (such as vincristine, doxorubicin, cyclophosphamide alternating with ifosfamide and etoposide) and sometimes radiation therapy. Despite aggressive treatment, the prognosis remains poor, with many patients experiencing recurrence and a high mortality rate. Early diagnosis and prompt initiation of combined therapy appear to offer the best chance for improved outcomes, though long-term survival data are limited due to the small number of reported cases in the medical literature.

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