A case report: primary extragonadal yolk sac tumor of penile shaft in a 2-year-old child.

A 2-year-old boy, who had the chief complaints of penile swelling and pain, was brought to the hospital by his mother. Penile contusion/trauma was suspected and he was admitted the same day to undergo emergency surgery to eliminate hematoma. The surgery revealed that the origin of the bleeding was not trauma but a tumor lesion of the penile shaft. It was histopathologically identified as a yolk sac tumor and no tumorous lesions were found except that in the penis. Therefore the patient was diagnosed as definitely having a yolk sac tumor originating in the penis. The patient received four cycles of cisplatin, etoposide and bleomycin treatment as adjuvant chemotherapy. Although it was impossible to completely resect the tumor, cisplatin, etoposide and bleomycin chemotherapy was effective and a complete response was achieved. We plan to carefully monitor the patient in the future.