Polyostotic fibrous dysplasia with secondary aneurysmal bone cyst in tibia

Polyostotic fibrous dysplasia (McCune-Albright) with rare multiple epiphyseal lesions in association with aneurysmal bone cyst and pathologic fracture

Fibrous dysplasia, including McCune-Albright syndrome, is a genetic, non-inheritable benign bone disorder that may involve a single or multiple bone, typically occurring in the diaphysis or the metaphysis of long bones. In very rare instances polyostotic fibrous dysplasia present involvement of the epiphysis in long bones. Aneurysmal bone cysts are benign, expansile, lytic bone lesions formed by cystic cavities containing blood, that may occur de novo or secondary to other lesions of bone, including fibrous dysplasia. We report a case of an 18-year-old female with polyostotic fibrous dysplasia (McCune-Albright syndrome) with diaphyseal and unusual multiple foci of epiphyseal involvement of long bones as well as in the patella, and a simultaneous aneurysmal bone cyst of the left femoral neck with pathologic fracture. This is the first report of a simultaneous aneurysmal bone cyst in a patient with polyostotic fibrous dysplasia (McCune-Albright syndrome) with involvement of diaphysis and epiphysis of long bones, highlighting that fibrous dysplasia should be included in the differential diagnosis of polyostotic tumors involving the diaphysis as well as the epiphysis. In patients with polyostotic fibrous dysplasia there should be an active search for lesions in the epiphysis.