The bony changes seen in this case are typical for polyostotic fibrous dysplasia with an associated secondary aneurysmal bone cyst in the right femoral neck; however, the presence of intramuscular myxomatous lesions indicate that this is not simply polyostotic fibrous dysplasia but rather Mazabraud syndrome. Fibrous dysplasia may be either monostotic or polyostotic in Mazabraud syndrome, but is typically polyostotic.
The intramuscular myxomas in this case were biopsy proven, however biopsy is not critical because the lesions are characteristic in this setting and there is no potential for malignant degeneration.
Less than 100 cases of Mazabraud syndrome have been reported.
This case was shared with me by the late and great Dr. Deborah Forrester.