Abstract
Primary pericardial synovial sarcoma is extremely rare, with few published cases in the literature. We report the case of an adolescent aged 13 years with primary pericardial synovial sarcoma discovered during tamponade, confirmed by molecular biology, and for whom treatment combined radiosurgery and adjuvant chemotherapy. The particularity of the case we are reporting stems from the young age of our patient (13 years) as well as the duration of remission, which is quite long (21 months) prior to a superior mediastinal relapse compared to cases reported in the literature. .