Classically, the alveolar subtype is characterized by a chromosomal translocation t(2;13)(q35;q14) or t(1;13)(p36;q14) fusing the PAX3 or PAX7 gene, respectively, to the FOXO1 gene, although fusion-negative cases of alveolar rhabdomyosarcoma (ARMS) occur; these share considerably more with the genomic profiles and biological behavior of embryonal rhabdomyosarcoma than with fusion-positive ARMS.
Using fluorescent in situ hybridization (FISH), the SRMS and the FRMS tumor cells of the elbow and the FRMS tumor cells of the testis were found to be negative forFOXO1A translocation in chromosome 13.
Identification of PAX3-FKHR-regulated genes differentially expressed between alveolar and embryonal rhabdomyosarcoma: focus on MYCN as a biologically relevant target.
The majority, but not all, alveolar rhabdomyosarcoma carry the specific PAX3(7)/FKHR-translocation, whereas there is no consistent genetic abnormality recognized in embryonal rhabdomyosarcoma.
By fluorescence in situ hybridization analysis, the tumor cells were negative forFKHR-disrupting translocations specific for alveolar type of RMS and for NMYC gene amplification.
A sample from a patient with a diagnosis of embryonal rhabdomyosarcoma on presentation and expression of PAX3-FKHR fusion transcript yielded a small focus of alveolar rhabdomyosarcoma and was reclassified as alveolar rhabdomyosarcoma.