Paratesticular rhabdomyosarcoma (RMS) is a rare malignant soft tissue tumor that originates from the mesenchymal tissue surrounding the testis, including the epididymis and spermatic cord. It predominantly affects pediatric and adolescent males, with a peak incidence in the second decade of life. Although it accounts for a small fraction of all pediatric malignancies, paratesticular RMS represents one of the more common genitourinary sarcomas in this age group. Clinically, it often presents as a painless scrotal mass, which may lead to delayed diagnosis due to its indolent onset and resemblance to benign conditions such as hydrocele or epididymitis. Timely diagnosis is crucial, as the tumor can rapidly progress and metastasize through lymphatic channels, particularly to the retroperitoneal and pelvic lymph nodes. Imaging studies and histopathologic evaluation, supplemented by immunohistochemistry, play a key role in establishing the diagnosis. Management typically involves a combination of surgical excision, chemotherapy, and in some cases, radiotherapy, depending on the stage and risk stratification. Early diagnosis and prompt multimodal treatment are critical for improved outcomes, as delayed intervention is associated with a higher risk of recurrence and reduced survival rates.

We report a case of a 12-year and 4-month-old boy who presented with a one-month history of painless right testicular enlargement. Physical examination revealed a firm, non-tender mass. Initial imaging via CT scan confirmed a right testicular mass. Tumor markers including alpha-fetoprotein and beta-human chorionic gonadotropin were within normal limits. A radical orchiectomy was scheduled electively; however, the patient developed cyanosis of the right testis, indicating tumor rupture. An urgent right radical orchiectomy was performed.

Histopathology confirmed embryonal rhabdomyosarcoma with a tumor size of 6.6 x 5.5 x 4.0 cm, negative margins, and no lymphovascular invasion. Immunohistochemistry was positive for WT1, Myogenin, MyoD1, and Desmin, supporting the diagnosis. Postoperatively, PET imaging revealed FDG-avid lymph nodes in the right external iliac and paraaortic regions, suggesting metastatic involvement. A Port-A catheter was placed, and chemotherapy was initiated using the TPOG RMS-2016 intermediate-risk protocol. The patient tolerated week 1 chemotherapy without major complications and was subsequently discharged.

This case underscores the importance of early recognition and timely intervention in paratesticular RMS. Although the primary tumor was localized at presentation, early lymphatic spread was detected, necessitating systemic chemotherapy. This case also illustrates the utility of PET-CT in staging and treatment planning for pediatric RMS.