Mazabraud syndrome

Mazabraud syndrome is a rare syndrome consisting of:

It is very rare, with only 81 cases in the global literature reported to 2012 13. It is most frequently seen in women (~70%) and usually presents in middle-age (mean age 46 years; range 17-82 years) 7

Patients usually present with a painless mass with a history of long duration 5. Intramuscular myxomas are commonly found in the thigh, shoulder, and buttocks and tend to be in the lower extremities 6. Strangely the right side is more commonly affected 9. Myxomas usually occur in the same extremity as the bony lesions, but typically later than them (years is common) in the natural history of the condition 9

Molecular genetic analysis has found that mutations in the GNAS1 gene, involved in cell proliferation, are expressed in both lesions 3,4.

The imaging features of the condition are those of fibrous dysplasia and of intramuscular myxomas, but also note:

  • fibrous dysplasia is usually polyostotic
    • monostotic has been reported 9
  • myxomas usually lower limbs and in close proximity to the bone disease
    • right > left

There is an increased risk of osseous malignant transformation. 

Although the malignant transformation of the myxoma has not been reported 8, a few cases of osteosarcoma and fibrosarcoma arising from fibrous dysplasia lesions have been reported 9.

High recurrence rate, locally or in adjacent muscles has been reported, with a time to recurrence of up to more than 10 years 10.

Non-malignant complications of the fibrous dysplasia include pathological fractures and bone pain.

The first case was described in the literature in 1926 11 but it was Mazabraud in 1967 who first recognised the association between the intramuscular myxomas and fibrous dysplasia 12

Bone tumours

The differential diagnosis for bone tumours is dependent on the age of the patient, with a very different set of differentials for the paediatric patient.

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Article information

rID: 6569
Section: Syndromes
Synonyms or Alternate Spellings:
  • Mazabraud's syndrome

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Cases and figures

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