Pediatric Head and Neck Rhabdomyosarcoma

  • Etiology: Malignancy of mesenchymal origin which does not necessarily arise in muscle
  • Imaging Orbital:
    — Unilateral
    — Extraconal
    — Usually well-circumscribed
    — Most often in medial-superior quadrant of orbit
    — If parameningeal in location look hard for CNS involvement
    — May have aggressive or non-aggressive or mixed effects on bone
  • Imaging MRI:
    — T1WI: Hypointense to intermediate
    — T1WI post contrast: Enhances heterogeneously
    — T2WI: Intermediate to hyperintense
    — DWI: Restricted diffusion
  • DDX: Infantile hemangioma
  • Complications: Metastasis to lung
  • Treatment:
  • Clinical:
    — Most common sarcoma in children
    — Most common extraoccular orbital malignancy in childhood
    — In all ages with mean age 6-8 years old,
    — Orbital rhabdomyosarcoma has best prognosis of all head and neck rhabdomyosarcomas
    — 50% head and neck and 30% genitourinary and 20% musculoskeletal
    — Embryonal cell type seen in infants is most common
    — Alveolar cell type seen in older children and affects musculoskeletal system and is more aggressive
    — Orbital has best prognosis

Radiology Cases of Head and Neck Rhabdomyosarcoma

MRI of rhabdomyosarcoma
Axial T1 MRI without (above left) and with contrast (above right) of the orbits show a solid homogenously enhancing mass arising superior and medially to the right orbit which shows restricted diffusion on diffusion weighted imaging (below right).
MRI of pediatric rhabdomyosarcoma of the parotid gland
Axial T1 MRI without contrast of the face (above left) shows an isointense lobular mass in the region of the left parotid gland that is hyperintense on axial T2 MRI (above right) and which enhances heterogeneously on axial T1 MRI with contrast and fat suppression (below left) and coronal T1 MRI with contrast (below right).