Mediastinal Alveolar Soft Part Sarcoma
ASPS; Malignant granular cell myoblastoma; Malignant myoblastoma; Malignant tumor of non-chromaffin paraganglia
Alveolar soft part sarcoma (ASPS) is a rare and very distinctive sarcoma of young patients. The tumor was originally described in 1952 as a unique soft tissue malignancy and named after its distinctive pseudoalveolar histologic appearance (Christopherson et al. 1952). Since its first description, numerous reports of such tumors have been published; however, uncertainty still exists today with regard to the line of differentiation and clinical behavior of these lesions. Speculation about the cell of origin had previously included the non-chromaffin paraganglia, a malignant form of angioreninoma or an unusual myogenic tumor; however, over the years ultrastructural and immunohistochemical studies have failed to support these assumptions. The more recent discovery that ASPS belongs to a group of translocation-associated sarcomas has raised the possibility...