Pathology of childhood and adolescent rhabdomyosarcoma - A report from theChildrens' Tumor Registry at the Gesellschaft fur Padiatrische Onkologie und Hamatologie

Rhabdomyosarcoma (RMS) is the most important and a very heterogeneous group of malignant soft tissue tumors of childhood and adolescence. The two majo r subtypes (embryonal and alveolar) share a common myogenic differentiation , but seem to be histogenetically not related. The so-called 'International Classification of Rhabdomyosarcoma 'includes, besides the two major subtyp es, the botryoid and leiomyomatous subtypes of embryonal RMS which are asso ciated with a better prognosis and are treated less aggressively according to current protocols. In addition, the solid variant of alveolar RMS is inc luded in the alveolar group of RMS. The identification of the various subty pes is necessary and important because the treatment with the current proto cols is also related to histology. Using conventional stains and immunohist ochemistry, these subtypes are distinguishable. Genetic analysis can be hel pful in the demonstration of t(2;13) or t(1;13) translocations in alveolar RMS. The identification of alveolar RMS with t(1;13) translocation might be come important in the future, because this type of translocation seems to b e related to a better prognosis as compared to tumors with a t(2;13) transl ocation.