Mazabraud syndrome

Case contributed by Dr Lukas Valkovic


Six months of thickening of the left thigh and recently associated with a sense of pressure. Previous hip fracture.

Patient Data

Age: 58
Gender: Female

There are two main morphologically different findings:

  • hypodense, irregular sclerotic lined lesions in sacral bone, both iliac bones and the left femur
  • multiple GGO lesions in the shaft/distal metaphysis of the left femur

In addition, there are multiple sharply demarcated cystoid lesions of variable size without significant enhancement in muscles in the following locations:

  • anterior and lateral muscle group left thigh (the largest single 77x65mm in the axial plane)
  • m. iliopsoas sin.
  • gluteal area + m. piriformis dx.

All these findings are consistent with intramuscular myxoid lesions and fibrous dysplasia.

Case Discussion

Mazabraud syndrome is a rare condition known for association of intramuscular myxomas and fibrous dysplasia.

Until 2004 there were only 55 documented cases. The first desciptions were documented in 1926 by Henschen, and the syndrome features were first described in 1967 by Mazabraud.

The differential diagnosis is broad and includes:

  • enchondroma
  • chondrosarcoma
  • bone cysts
  • fibrous dysplasia
  • osteosarcoma (especially in the form of monostotic fibrous dysplasia).

Myxoid lesions have to be distinguished mainly from malignant lesions like malignant histiocytoma, liposarcoma, sarcoma and chondrosarcoma. Patients often report painless mass which may be associated with bone deformities and fractures.

Molecular analysis revealed a mutation in the gene GNAS1. It is necessary to exclude malignancy histologically. Bone scintigraphy is suitable for determining the activity of the disease and multicentricity. CT is appropriate to determine the extent of bone lesions. Myxomas in MRI images are sharply defined (T1 hypointense, T2 hyperintese). After administration of contrast, you can differentiate the proportion of solid tissue and fibrous septa. Malignant transformation of myxoma is not recorded, although they are often present with local recurrence after incomplete resection. Treatment is mainly conservative, surgical solution is indicated for prevention of pathological fractures or bone deformities.

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