Sarcomas of the mediastinum are rare.The incidence in pediatric age is unknown.Its symptoms are caused by the compression of structures in the mediastinum.We present a case of a 15-year-old adolescent, she had dyspnea and chest pain, an anterior mediastinal mass was identified, in imaging studies the mass had various areas of soft tissue density and fatty tissue with histology reporting liposarcoma.She was managed with surgical resection and postoperative radiotherapy.Less than 25 cases have been reported in children under 18 years of age, surgical management is the mainstay in treatment and the prognosis is given by complete resection of the lesion.