Alveolar rhabdomyosarcomas are a type of rhabdomyosarcoma and accounts for 20-40% of all rhabdomyosarcomas 1-2. Unlike embryonal rhabdomyosarcomas, which are more common, these tumours occur in slightly older individuals, typically 10-25 years of age 1.
Although these tumours can be found essentially anywhere, they are more frequently situated in the deep compartments of the extremities 1-2.
Specific genetic abnormalities have been identified, that are specific for alveolar rhabdomyosarcomas. They include t(2;13) and t(1;13) chromosomal translocations resulting in PAX3-FKHR and PAX7-FKHR gene fusions 2.
The features are non-specific (see radiographic features in the parent article: rhabdomyosarcoma), although in general alveolar rhabdomyosarcomas tend to have multiple areas of necrosis 1.