Fetal Rhabdomyoma
A benign mesenchymal tumour of skeletal muscle differentiation occurring predominantly in the head and neck region of infants and young children, recognised by primitive myxoid stroma and immature rhabdomyoblasts.
Full Definition
Fetal rhabdomyoma is the most common subtype of rhabdomyoma in paediatric practice and presents chiefly in the post-auricular region, neck, and nasopharynx of children under three years of age. Histologically, it is composed of spindle-shaped immature rhabdomyoblasts embedded in a myxoid stroma, mimicking fetal muscle at approximately 7–12 weeks of development. Unlike rhabdomyosarcoma, fetal rhabdomyoma lacks significant nuclear atypia, mitotic activity, or infiltrative growth. Awareness of tuberous sclerosis as an association (particularly with the cardiac subtype) is pertinent in clinical context notes. Editors must distinguish it clearly from rhabdomyosarcoma to avoid implying malignancy.
Usage
Usage note: Always include the 'fetal' qualifier; 'rhabdomyoma' alone may refer to the adult or genital subtypes.
In Context
- "The post-auricular mass in the six-month-old was excised and diagnosed as fetal rhabdomyoma, with no evidence of malignancy." — Paediatric surgical pathology report
- "Editors must not shorten 'fetal rhabdomyoma' to 'rhabdomyoma' without the qualifier, as the adult and genital subtypes are distinct entities." — Editorial note