Paratesticular Embryonal Rhabdomyosarcoma Masquerading as Epididymitis: A Diagnostic Challenge in Adolescents.

Paratesticular rhabdomyosarcoma is a rare malignancy in children and adolescents that frequently presents diagnostic challenges when mimicking benign inflammatory conditions. We report the case of a 14-year-old previously healthy male who presented with acute right scrotal pain and swelling initially diagnosed as epididymo-orchitis. Despite 1 month of intensive antibiotic therapy including intravenous meropenem, the patient showed no clinical improvement. Serial ultrasound examinations demonstrated a heterogeneous paratesticular mass with increased vascularity, prompting MRI evaluation that revealed an 8 × 6.4 × 9.5 cm heterogeneous enhancing mass. CT staging showed prominent para-aortic and inguinal lymph nodes without distant metastases. The patient underwent radical inguinal orchiectomy, and histopathology confirmed embryonal rhabdomyosarcoma with spindle cell features and focal anaplasia. Immunohistochemistry demonstrated positive staining for desmin and myogenin, confirming skeletal muscle differentiation. The patient was referred for multimodal chemotherapy according to Children's Oncology Group protocols. This case highlights the critical importance of maintaining high clinical suspicion for paratesticular malignancy when pediatric scrotal masses fail to respond to appropriate antibiotic therapy, as diagnostic delays can significantly impact staging and treatment outcomes.