Two cases of Mazabraud syndrome and identification of a GNAS R201H mutation by next-generation sequencing

Excerpt

The first patient is a 43-year-old female with a history of left hip pain, which began 1 month prior to her presentation. At the onset, she felt a “pop.” Her medical history was otherwise unremarkable. X-rays taken showed a fracture of the proximal left femur and femoral neck, as well as sclerotic changes suggestive of a blastic process concerning for metastatic disease (Fig. 1a). CT scan of the abdomen and pelvis also showed fracture of the left femoral neck, as well as focal areas of abnormal architecture within the intramedullary canal of the left femur, suggestive of fibrous dysplasia. In addition, an 8.8 × 3.9 × 3.6 cm low-attenuation fluid density mass was seen that displaced the muscles of the left thigh. To further characterize this soft tissue mass, a multiplane multisequence MRI using 13 mL of MultiHance intravenous contrast was conducted. MRI of the left upper leg corroborated the bony findings on CT scan as polyostotic fibrous dysplasia (Fig. 1b, c). Multiple soft tissue lesions that demonstrated low signal on T1 and increased signal on inversion recovery were identified within the vastus intermedius, adductor magnus, and in the facial plane between the vastus lateralis and tensor fascia lata. These masses were radiographically consistent with myxomas. Based upon the imaging findings, a presumptive diagnosis of Mazabraud syndrome (MS) was made. To confirm this diagnosis, excision of the left thigh soft tissue masses was conducted. In addition, an open reduction and internal fixation of the left femoral neck was performed.

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