RESUMO
Alveolar rhabdomyosarcoma (ARMS), a histological subtype of rhabdomyosarcoma (RMS), is characterized by an unfavorable clinical outcome. In most ARMS cases, an indicative chromosomal alteration is identified. The recurrent translocation of FKHR with either PAX3 or PAX7 genes results in the encoding of chimeric transcription factors that boost tumorigenesis. Besides structural mutations, the copy number of these genes also contributes to the oncogenic activity. In our case, a 12-year-old female patient was diagnosed with a 4 cm pelvic mass. Histopathological examination indicated an alveolar type of RMS. Subsequent FISH analysis with a dual color break-apart probe identified positive signals of FKHR3 gene break, as well as the rare event of a synchronous aneuploidy and gene deletion of FKHR. Our findings lead to the conclusion that a systematic break-apart probe FKHR FISH analysis in ARMS, confirms the diagnosis and elucidates the full spectrum of genomic alterations of this malignancy.