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Rhabdomyosarcoma : Classification

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Histologic Classification: A variety of classification schemes for rhabdomyosarcomas (RMS) have been proposed over the years by different groups. The International Classification of Rhabdomyosarcoma categorizes various subtypes into prognostic groups. Any alveolar architecture or cytology earns the tumor an alveolar designation. Pleomorphic RMS is excluded in this classification since it is uncommon in children.

  • Superior Prognosis (botryoid, spindle cell)
  • Intermediate Prognosis (embryonal)
  • Poor Prognosis (alveolar, undifferentiated sarcoma)
  • Prognosis Not Presently Evaluable (rhabdoid)
The 4th Edition of the WHO Classification of Tumors of Soft Tissue and Bone recognizes four major subtypes of RMS. In this classification scheme, botryoid type is placed under embryonal RMS instead of being recognized as an independent diagnosis. Spindle cell/sclerosing type was established as a histologic type separated from embryonal RMS.
  • Embryonal
  • Alveolar
  • Pleomorphic
  • Spindle Cell/Sclerosing

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