Rhabdomyosarcoma is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

Rhabdomyosarcoma (RMS) is a malignancy of primitive mesenchymal cells with myogenesis capacity, which are in skeletal muscle tissues. It occurs mainly as primary malignancy, but can also be a component of heterogeneous neoplasias, like malignant teratoma.

  • Common anatomic sites:
    • Head and neck (common primary site in young children and are almost always of the embryonal type)
    • Genitourinary (mostly of the embryonal type)
    • Musculoskeletal (extremities are the most common primary sites in adolescents and adults)
  • The International Classification of RMS describes four major subtypes:
    • Embryonal RMS (ERMS): corresponds to 60–70% of pediatric cases. It is of early onset and the most common subtype in children. It is also more likely to occur in the head, neck, and genitourinary areas. ERMS is subdivided into:
      • Classic: groups most of the cases
      • Botryoid: is typically seen in infants, although can happen in children <4 years of age
      • Spindle cell: corresponds to 3% of cases and affects mostly young children
        • Both botryoid and spindle cell variants have better prognosis than the classical one.
    • Alveolar RMS (ARMS): represents 30% of pediatric cases. It is more common in the trunk, perineum/perianal area, and extremities. It is very aggressive.
    • Anaplastic (children)/pleomorphic (adults) is usually seen in patients aged 30 to 50 years, rarely in children.

Epidemiology

Incidence
  • 4.5 cases of RMS per 1 million children per year
  • 50% of pediatric cases occur before the age of 10 years.
  • RMS accounts for 60% of sarcomas in children and adolescents.
  • In adults, RMS represents 3% of all soft tissue sarcomas in adults.

Prevalence
  • RMS comprises 3.5% of all childhood cancers.
  • The embryonal subtype is more frequent in males (male:female ratio, 1.5)
Genetics

Genetic characteristics vary according to the RMS subtype (1,2):

  • Alveolar:
    • t(2;13)(q35;q14); causing PAX3-FOXO1 fusion
    • t(1;13)(p36;q14); causing PAX7-FOXO1 fusion
    • t(X:2)(q13;q35); causing PAX3-FOXO4 fusion
    • t(2;2)(q35;p23); causing PAX3-NCOA1 fusion
    • t(2;8)(q35;q13); causing PAX3-NCOA2 fusion
    • t(8;13)(p12;q13); causing FOXO1-FGFR1 fusion
  • Embryonal:
    • Complex genetic aberrations affecting multiple genes; among them, MYOD1 mutations
    • Loss or uniparental disomy of 11p15.5 +2,+8,+11,+12,+13,+20 affecting the genes IGF-2, H19, CDKN1C, and/or HOTS
  • Spindle cell RMS:
    • 8q13 rearrangements involving SRF-NCOA2 and TEAD1-NCOA2

Risk Factors

RMS is associated with high birth weight, large gestational size for age, and the genetic conditions described below.

Commonly Associated Conditions

  • Beckwith-Wiedemann syndrome (11p15 mutations)
  • Costello syndrome (germline HRAS mutations)
  • Li-Fraumeni (germline TP53; also known as p53 mutations)
  • Neurofibromatosis type I (NF1 mutations)
  • Noonan syndrome (PTPN11 mutations)
  • Pleuropulmonary blastoma (DICER1 mutations)

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Citation

* When formatting your citation, note that all book, journal, and database titles should be italicized* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Rhabdomyosarcoma ID - 117569 ED - Baldor,Robert A, ED - Domino,Frank J, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117569/all/Rhabdomyosarcoma PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -