AUTHOR=Zheng Chuanxi , Zhou Yong , Luo Yi , Zhang Hongying , Tu Chongqi , Min Li 

TITLE=Case Report: Primary Ewing Sarcoma of the Penis With Multiple Metastases

JOURNAL=Frontiers in Pediatrics

VOLUME=Volume 8 - 2020

YEAR=2021

URL=https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2020.591257

DOI=10.3389/fped.2020.591257

ISSN=2296-2360

ABSTRACT=Background: Ewing sarcoma is the second most common malignant bone tumor in children, but it rarely originates from extra-skeletal sites. The commonly involved sites of soft tissue include paravertebral spaces, lower extremities, pelvis, head and neck, while primary extra-skeletal Ewing sarcoma (EES) located in the genitals is extremely rare. 
Case Presentation: We report a young patient who presented to our hospital with painful erection of penis and limited motion of left hip. Magnetic resonance imaging showed a hyperintense mass with invasion of adjacent tissue in the penis and a heterogeneously high signal lesion in the left proximal femur. 18F-fluorodeoxyglucose positron-emission tomography detected wide-spread metastatic lesions in the bilateral lung and multiple skeletons. An incisional biopsy of penis was performed; the histopathological findings and EWS gene translocation identified by molecular analysis confirmed the diagnosis of Ewing sarcoma. Subsequently, the punch-biopsy specimen from left femur showed undifferentiated small round cells, a finding consistent with the microscopical presence of Ewing sarcoma metastasis. However, after the first course of multiagent chemotherapy, the penile mass did not obtain stabilization, instead growing progressively with surface ulceration and multi-drug resistant bacteria infection. Despite receiving the antibiotic and maximal supportive therapy, the patient died from sepsis and lung metastasis complications in the intensive care unit two months later. 
Conclusion: This case indicates that EES as a subtype of Ewing sarcoma is rare, but it virtually can occur in any soft tissue site, even in the genitals. Therefore, clinicians need to distinguish this entity from other soft tissue sarcomas with rapid progression since early diagnosis and timely treatment of EES is pivotal for a favorable prognosis.