Primary Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of the penis: a report of an extraordinarily unusual site and a literature review of extraskeletal Ewing's sarcoma.

Ewing's sarcomas/primitive neuroectodermal tumors (ES/PNETs) arise from a multipotent progenitor cell and are considered to be of neuroectodermal derivation. Most tumors commonly arise in the skeletal system, which are the classic ES/PNET and occasionally occur in the soft tissue of extraskeletal sites, which are named extraskeletal Ewing's sarcomas (EES/PNET). This study reports a case of a 28-year-old man with primary EES/PNET of the penis.