Ewing sarcoma/primitive neuroectodermal tumor of the ureter: A case report and literature review

 Correspondence to: Bangxian Tan. Email: tbx_nsmc@126.com © 2021 Huazhong University of Science and Technology In 1918, Stout described, for the first time, a solid tumor originating from the ulnar nerve, which was later named primitive neuroectodermal tumor (PNET). Subsequently, Ewing discovered a sarcoma he named after himself—Ewing sarcoma (ES)—composed of long bones’ undifferentiated cells. In 1973, Hart and Earle proposed that PNET is a malignant small round cell tumor originating from the neural crest [1]. According to the location, PNET can be divided into central PNET and peripheral PNET (pPNET). Because pPNET and ES share the same chromosomal translocation, approximately 85% of ES and pPNET present a specific t(11;22)(q24;q12) balanced translocation, which in 2002, the World Health Organization classified as the ES family of tumors that also includes Askin tumors (ES of the chest wall). ES/PNET is a highly malignant and extremely rare small round cell tumor, showing varying degrees of neuroectodermal differentiation, which usually occurs in children and adolescents. ES/PNET mainly affects the bones or soft tissues but is not common in the urinary tract. It is mostly reported in case forms, such as in the kidney and bladder, but rare in the ureter. It is challenging to make a preoperative diagnosis and identify other diseases based on clinical symptoms and imaging findings. The diagnosis mainly depends on histological biopsy, immunohistochemistry (IHC), and gene detection. Complete surgical resection combined with adjuvant radiotherapy and chemotherapy is the primary treatment method, whereas a new type of targeted immunotherapy is now being investigated in clinical trials [2].