Sarcopedia

MalignantSoft tissue

Rhabdomyosarcoma

Synonyms: Embryonal rhabdomyosarcoma, alveolar RMS, pleomorphic RMS

Most common soft tissue sarcoma in children

Quick Facts

Behaviour

Malignant

Category

Soft tissue

Grade

High

Synonyms

  • Embryonal rhabdomyosarcoma
  • alveolar RMS
  • pleomorphic RMS

Category

Soft tissue

Behaviour

Malignant

Grade

High

Gender

M = F

Tissue of Origin

Skeletal muscle

Epidemiology

  • Most common soft tissue sarcoma in children
  • Peak incidence <5 years for embryonal subtype
  • Alveolar: slightly older children

Clinical Features

  • Rapidly growing mass
  • Pain if deep location
  • Site-dependent symptoms (biliary, bladder obstruction)

Location

  • Biliary tract (botryoid)
  • Bladder/prostate (botryoid)
  • Extremities
  • Head and neck
  • Parameningeal locations

Imaging

  • MRI primary site - essential for surgical planning
  • CT chest/abdomen/pelvis - metastatic staging

Pathology

  • Small round cells with myogenic differentiation
  • Embryonal: myxoid background
  • Alveolar: nested pattern with PAX-FOXO1 fusion

Genetics

  • PAX3-FOXO1 in alveolar (t(2;13))
  • PAX7-FOXO1 in alveolar (t(1;13))
  • PAX-FOXO1 negative in embryonal

Treatment

  • Multiagent chemotherapy (VAC/IE)
  • Local control: surgery and/or radiotherapy

Prognosis

  • Embryonal: 70% 5-year survival
  • Alveolar: 50% 5-year survival
  • Stage and histology critical prognostic factors

Key Points

  • Most common soft tissue sarcoma in children
  • PAX-FOXO1 status defines risk stratification
  • Multimodal therapy standard

Workup - Blood Tests

  • FBC, U&E, LFTs - baseline and pre-chemo
  • LDH - prognostic marker

Workup - Local Imaging

  • MRI primary site with gadolinium - local staging
  • CT chest/abdomen/pelvis - metastatic staging
  • PET-CT - systemic staging

Workup - Biopsy

  • Core needle biopsy - confirm diagnosis
  • PAX-FOXO1 FISH essential for prognostic stratification

Workup - Staging

  • CT chest/abdomen/pelvis - metastases
  • PET-CT - staging

Workup - Other

Paediatric oncology MDT mandatory

Follow-up Summary

  1. 1

    Year 1

    2-monthly clinical examination, CXR, plain films of primary bony site; soft tissue tumours - baseline end-of-treatment MRI/CT primary site, thereafter at clinician's discretion; radiotherapy as definitive local treatment - baseline end-of-treatment MRI/CT, then at 6 and 12 months; end of Year 1 - gonadal function and renal function

  2. 2

    Years 2–3

    3-monthly clinical examination, CXR, plain films of bony primary site; MRI of soft tissue primary site at clinician's discretion; radiotherapy patients - MRI/CT at 18 and 24 months; MUGA/ECHO 2 years post-diagnosis; annual renal function

  3. 3

    Year 4

    6-monthly clinical examination, CXR, plain films of primary site; MRI of soft tissue primary at clinician's discretion; MUGA/ECHO 4 years post-diagnosis; annual renal function

  4. 4

    Year 5

    6-monthly clinical examination, CXR, plain films of primary site; annual renal function

  5. 5

    Years 6–10

    Annual clinical examination, CXR, plain films of primary site; MUGA/ECHO 6 years post-diagnosis; annual renal function

  6. 6

    Discharge at 10 years after surgery

Medical disclaimer

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