Rhabdomyosarcoma, Mediastinal

Definition

Rhabdomyosarcoma is the most common soft tissue sarcoma in children accounting for 4–8% of all malignancies in children under the age of 15 years. It is an uncommon neoplasm in adults in whom it merely accounts for 2–5% of all soft tissue sarcomas. These tumors show rhabdomyoblastic differentiation and most commonly occur in the extremities, head and neck area, or genitourinary tract. Rhabdomyosarcomas arising in the mediastinum are rare and most often a component of a teratoma, non-teratomatous germ cell tumor, or thymic carcinosarcoma. Pure mediastinal rhabdomyosarcomas have only sporadically been reported in the literature as case reports and only a single larger series of four cases (Suster et al. 1994). The tumors can be subdivided into three large categories based on histological appearance and genetic features: embryonal, alveolar, and pleomorphic rhabdomyosarcoma. The embryonal and alveolar types predominate in children, while the pleomorphic variant has a higher...