Inflammatory rhabdomyoblastic tumor: A review and update.

Inflammatory rhabdomyoblastic tumors (IRMT), clinicopathologically and genetically distinct skeletal muscle tumors of borderline malignancy. These rare tumors were originally believed to represent "inflammatory leiomyosarcomas" and have also been reported as "histiocyte-rich rhabdomyoblastic tumor" and "low-grade inflammatory myogenic tumor". In addition to representing the only skeletal muscle tumor of borderline malignancy, IRMT may also rarely progress to fully malignant rhabdomyosarcoma. The clinicopathologic, immunohistochemical and molecular genetic features of IRMT and rhabdomyosarcomas arising from IRMT are reviewed.