Embryonal Prostatic Rhabdomyosarcoma: A Case Report

Sarcomas account for 0.1 to 0.2% of all prostatic malignancies. Rhabdomyosarcoma is a malignant tumor that shows skeletal muscle (sarcomeric) differentiation. About 35% of rhabdomyosarcomas occur in the head-neck, 40% on the limbs and other areas and 25% in the genitourinary system. Only 5% of them arise in the prostate or bladder. Primary prostatic rhabdomyosarcoma usually develops in infancy and childhood at around 10 years of age. A 20-year-old male presenting with a complaint of right-left side pain was diagnosed with bilateral hydronephrosis after a series of tests. His urethrography showed a severely narrowed, firm and fixed prostatic urethra, so a needle biopsy was performed. The microscopic examination detected an invasive tumor within fibromuscular stroma and prostate glands. The tumor consisted of oval to round tumor cells with hyperchromatic nuclei and irregular contours in places, as well as cells with occasional eosinophilic cytoplasm. Immunohistochemically, the tumor cells showed a positive immunoreaction for myogenin, desmin and c-kit. Based on these findings, the patient was diagnosed with embryonic rhabdomyosarcoma. The case has been presented for discussion, since prostatic embryonic rhabdomyosarcoma is a rare disease with diagnostic challenges in differentiating from other prostatic tumors.