rhabdomyosarcoma
Pronunciation: rab-doe-my-oh-sar-KOH-mah
Most common soft tissue sarcoma in children, arising from primitive mesenchymal cells.
Full Definition
Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in pediatric patients, accounting for approximately 50% of childhood soft tissue malignancies. These tumors arise from primitive mesenchymal cells that have the potential to differentiate toward skeletal muscle. The two main histological subtypes in children are embryonal rhabdomyosarcoma (more common, better prognosis) and alveolar rhabdomyosarcoma (associated with specific translocations and worse prognosis). Common sites include the head and neck region, genitourinary tract, and extremities. Diagnosis requires immunohistochemical staining for muscle markers such as desmin, MyoD1, and myogenin, along with molecular testing for characteristic translocations in alveolar types.
Usage
Usage note: Distinguish from benign rhabdomyoma. Subtypes (embryonal, alveolar) significantly impact prognosis and treatment.
In Context
- "Immunohistochemistry confirmed the diagnosis of embryonal rhabdomyosarcoma with positive staining for myogenin and MyoD1." — Pathology report
- "Molecular testing revealed PAX3-FOXO1 fusion characteristic of alveolar rhabdomyosarcoma." — Molecular pathology report