Primary primitive neuroectodermal tumor of urinary bladder in a child: a case report and literature review

Objectives: The present study is to report the clinical and pathological features of the primary primitive neuroectodermal tumor, Ewing's sarcoma (PNET/EWS) of urinary bladder. Methods: A case of PNET/EWS in urinary bladder was reported. The literatures of 14 cases of PNET/EWS were reviewed according to clinical manifestation and pathological characteristics. Results: A 2-year-old boy presented with dysuria was referred to our institution for further management in December 2014. Pelvic computed tomography showed a large intravesical tumor. Cystoscopy showed a large intravesical mass arising from the neck and left side of the bladder, and then biopsy was made. Histopathological examination revealed sheets of uniform, small, round, and oval cells, which presented scarce cytoplasm, hyperchromatic nuclei, inconspicuous nucleoli, and abundant atypical mitotic figures. From the further immunohistochemical characterization, the tumor cells demonstrated strong reactivity to CD99 and Vim. A definitive diagnosis of PNET of the bladder was established. Catheterization was performed, but chemotherapy was refused by the parents, and the patient was discharged according to his parents' will. The patient died 4 months later. Conclusions: Bladder PNET is an extremely rare malignant tumor. The diagnosis is based on histological, immunohistochemical and molecular pathologic findings. It is a kind of highly aggressive tumor and has very poor prognosis. Radical excision combined with adjuvant chemotherapy and radiotherapy appears to be the best treatment.