A Rare Pediatric Paratesticular Spindle Cell Rhabdomyosarcoma and Systematic Literature Review.

Paratesticular rhabdomyosarcoma (RMS) is a rare malignancy, representing ~3% of all pediatric soft tissue tumors. The spindle cell subtype, a variant of embryonal RMS, is particularly uncommon but is typically associated with a favorable prognosis. We report the case of a 12-year-old boy who presented with a painless, progressively enlarging right inguinoscrotal mass. Imaging studies revealed a heterogeneous lesion without distant metastasis, and tumor markers were within normal limits. The patient underwent radical orchiectomy, and histopathology confirmed spindle cell RMS, with immunohistochemical positivity for myogenin and desmin. After completing treatment with the Children's Oncology Group (COG)-ARST0531 Vincristine, Actinomycin D, and Cyclophosphamide protocol, a retroperitoneal lymph node recurrence was detected 1 year later. Management consisted of surgical resection and escalated chemotherapy per the COG-ARST0431 protocol, with subsequent imaging showing no evidence of disease. This case demonstrates that despite a favorable histology, paratesticular spindle cell RMS carries a risk of late, regional recurrence, underscoring the necessity of vigilant long-term surveillance. We also performed a systematic literature review to contextualize our findings, focusing on clinical presentation, therapeutic strategies, and outcomes.