Primary primitive neuroectodermal tumor in pelvic cavity: an unusual case and literature review

Primitive neuroectodermal tumor (PNET) in the pelvic cavity is a relatively rare tumor of neural crest origin. We report a 35-year-old lady diagnosed as pelvic cavity PNET treated with 6 cycles of chemotherapy (VAC regimen then followed by IE regimen), and the final clinical effect was partial remission (PR). The patient did not show any characteristic symptoms except for left lower limb numbness and weakness. The diagnosis was confirmed by the imageology as well as immunohistochemistry of ultrasound-guided puncture and biopsy, which showed positive for Mic-2 (CD-99 antigen), vimentin, neuron-specific enolase (NSE), and Chromogranin A (CgA). She didn’t have the chance to take the radical operation not only due to the size of the tumor, but invasion of the surrounding tissues. Therefore, she only received chemotherapy and was regularly followed for 18 months at our clinic without evidence of disease progression. The result of immunohistochemistry is a useful supplement in differential diagnosis, furthermore, CAV and IE alternating chemotherapy has high objective response rate for metastic PNET. The incidence of peripheral PNET (pPNET), their clinical and pathological features are discussed with a review of the literature.