Histopathological classification of childhood rhabdomyosarcoma: a report from the International Society of Pediatric Oncology pathology panel.

Five hundred thirteen soft tissue tumours of childhood referred to the International Society of Pediatric Oncology (SIOP) Rhabdomyosarcoma study have been reviewed. The period covered was from January 1975 to December 1983. Three hundred thirty-nine neoplasms were regarded as embryonal rhabdomyosarcoma. The histological diagnosis of all referred tumours is given, and a classification of rhabdomyosarcomas developed during the course of the study is described. The relationship between histological subtypes and aspects of clinical behaviour is presented. The classification is thought to be helpful in diagnosis and also in assessment of the likelihood of recurrence and/or metastasis of childhood rhabdomyosarcoma.