Musculoskeletal case 8. Mazabraud's syndrome--intramuscular myxoma associated with fibrous dysplasia.

The association of fibrous dysplasia and intramuscular myxoma is a rare disease known as Mazabraud's syndrome. Both lesions tend to occur in the same anatomical region. The relationship between fibrous dysplasia and myxoma remains unclear, where an underlying localized error in tissue metabolism has been proposed to explain this occasional coexistence. Another example of this syndrome in a 52 year-old woman is reported. The patient presented with a soft tissue mass at the anteromedial mid part of the left thigh. After excision of the mass, three separate bone lesions were detected in her control MRI. The soft tissue mass was misdiagnosed as liposarcoma in another center, and the bone lesions were interpreted as metastasis. The hypocellularity and the indistinct vascular pattern of the lesion were consistent with myxoma. The Jam-Shidi needle biopsies of the osseous lesions were diagnosed as fibrous dysplasia. The recognition of this entity is important for appropriate management of the patient. Patients with soft tissue myxomas should be thoroughly examined for fibrous dysplasia. The greater risk of sarcomatous transformation in fibrous dysplasia with Mazabraud's syndrome should also be kept in mind.