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Illustration 1. The patient, a 32-year-old man with polyostotic fibrous dysplasia, presented with increasing deformities of the skull and ribs and pain in both ankles. He had been diagnosed as having fibrous dysplasia at the age of 11, had had cranial dysmorphia since childhood, and had experienced a pathologic fracture of the right femur at 14 years old. A 99mTc–methylene diphosphonate bone scan showed multiple areas of increased radiotracer uptake in the long bones, the skull, and the ribs (left). Magnetic resonance imaging (MRI) was performed to rule out neurologic compression due to the skull lesion. T1-weighted images acquired after intravenous administration of gadolinium-based contrast material showed no brain damage, but revealed a bilateral thickening of the skull vault and skull base, with intermediate tissue signal indicating fibrous areas with cystic components and lower signal indicating greater matrix mineralization (right) (1). Clinical examination revealed the presence of café-au-lait spots and subcutaneous nodules that corresponded to soft tissue myxomas. Mazabraud syndrome, which is an association of intramuscular myxomas with fibrous dysplasia, was suspected. There are currently ∼70 reported cases of Mazabraud syndrome. The syndrome is found predominantly in women, with the lower limbs most frequently affected, and fibrous dysplasia occurring more commonly in the femur and pelvis (2). In this patient, who had cranial involvement, we also excluded acromegaly by measuring the insulin-like growth factor 1 level. According to the new French guidelines recently presented for the diagnosis and management of fibrous dysplasia (3), when cranial localization is suspected during clinical or simple radiologic examination, a computed tomography scan or MRI must always be performed in order to rule out meningioma and compressive local complications.

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