A rhabdomyosarcoma is a malignant tumor derived from skeletal muscle. It is the most common cancer of soft tissue among children and usually affects the head and neck. Rhabdomyosarcomas are classified by histology into five groups: anaplastic, alveolar, botryoid, embryonal and spindle cell emgryonal. Embryonal and alveolar rhabdomyosarcoma are the most common types, comprising 60 and 31 percent of the cases, respectively. The following steps will show how to diagnose a rhabdomyosarcoma.
Observe a localized swelling in the head or neck as the most common early symptom of a rhabdomyosarcoma. It is usually not painful and other symptoms depend on the specific location. These can include airway obstruction, a foul smell, hearing loss, nasal discharge and falling forward.
Obtain a Magnetic Image Resonance (MRI) scan if a rhabdomyosarcoma is suspected. An MRI will define the mass and determine its extent into adjacent organs. Other imaging techniques also are helpful in making the diagnosis.
Perform an open biopsy as the preferred method for tissue sampling. A core needle biopsy can be used as an alternative.
Use a fluorescent in situ hybridization (FISH) to determine the alveolar subtype and differentiate a rhabdomyosarcoma with other tissue types. A reverse transcriptase-polymerase chain reaction can be used to assess alveolar rhabdomyosarcoma if FISH is not available or the results are uninformative.
Differentiate rhabdomyosarcoma histologically with other round blue cell tumors. Rhabdomyosarcoma cells are often variably differentiated along the myogenesis pathway and may stain positive for actin, desmin and myoglobin.