Encyclopedia of Pathology

Living Edition
| Editors: J.H.J.M. van Krieken

Intramuscular Myxoma

Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-28845-1_5407-1


Benign soft tissue tumor composed of benign-appearing spindle cells set in an abundant myxoid hypovascular stroma.

Clinical Features

  • Incidence

    It is a rare tumor. It may occur sporadically or in the context of Mazabraud syndrome (single or multiple intramuscular myxomas associated with monostotic or polyostotic fibrous dysplasia) (Nielsen and Hogendoorn 2013).

  • Age

    It generally affects adult patients, with a peak in the fourth to seventh decades of life.

  • Sex

    Females are more frequently affected than males.

  • Site

    It generally arises in the extremities, especially in the thigh.

  • Treatment

    Simple surgical excision is curative.

  • Outcome

    It is a benign lesion, with a low risk of local recurrence after incomplete surgery. No malignant transformation has been reported (Nielsen and Hogendoorn 2013).


Size usually ranges between 5 and 10 cm in greatest diameter. The tumor appears well-circumscribed and diffusely gelatinous on cut surface, sometimes featuring fluid-filled cystic...
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  1. Enzinger, F. M. (1965). Intramuscular myxoma: A review and follow-up study of 34 cases. American Journal of Clinical Pathology, 43, 104–113.CrossRefGoogle Scholar
  2. Miettinen, M., Höckerstedt, K., Reitamo, J., & Tötterman, S. (1985). Intramuscular myxoma – A clinicopathological study of twenty-three cases. American Journal of Clinical Pathology, 84(3), 265–272.CrossRefGoogle Scholar
  3. Nielsen, G. P., & Hogendoorn, P. C. W. (2013). Intramuscular myxoma. In C. D. M. Fletcher, J. A. Bridge, P. C. W. Hogendoorn, & F. Mertens (Eds.), World Health Organization classification of tumours. Pathology and genetics of tumours of soft tissue and bone (pp. 195–196). Lyon: IARC Press.Google Scholar
  4. Okamoto, S., Hisaoka, M., Ushijima, M., Nakahara, S., Toyoshima, S., & Hashimoto, H. (2000). Activating Gs(alpha) mutation in intramuscular myxomas with and without fibrous dysplasia of bone. Virchows Archiv, 437(2), 133–137.CrossRefGoogle Scholar
  5. van Roggen, J. F., McMenamin, M. E., & Fletcher, C. D. (2001). Cellular myxoma of soft tissue: A clinicopathological study of 38 cases confirming indolent clinical behaviour. Histopathology, 39(3), 287–297.CrossRefGoogle Scholar

Authors and Affiliations

  1. 1.IRCCS Istituto Ortopedico RizzoliBolognaItaly