Alterações Citogenético-Moleculares no Gene FOXO1 em uma Criança com Rabdomiossarcoma Alveolar: Relato de Caso

Introduction: Rhabdomyosarcoma (RMS) is the most common soft tissue tumor of childhood. It can be classified into two main subtypes: alveolar rhabdomyosarcoma (aRMS) and embryonal (eRMS). In aRMS the prognosis is unfavorable when compared to eRMS, requiring intensified treatment, thus the distinction between both subtypes is fundamental. Cytogenetically, aRMS present chromosomal translocations involving the FOXO1 gene in 80% of the cases. The fluorescence in situ hybridization methodology (FISH) has been widely used to characterize aRMS subtype. Case Report: A 7-year-old female patient presented with parameningeal aRMS, non-metastatic at diagnosis. FISH analysis showed translocation involving the FOXO1 gene and an extra copy of this gene. The patient was enrolled in the EpSSG treatment protocol, classified as a high-risk group and received chemotherapy and radiotherapy. At the end of treatment a partial response was observed, and second line chemotherapy was started. There was no clinical-radiological response and the patient progressed with local disease, refractory to rescue treatment and died of disease one year after diagnosis. Conclusion: To our knowledge, this is the first case of aRMS presenting FOXO1 gene translocation and an extra copy of this gene in separate clones. More studies are necessary to understand the prognostic significance of these alterations.