Craniospinal Polyostotic Fibrous Dysplasia, Aneurysmal Bone Cysts, and Chiari Type 1 Malformation Coexistence in a Patient with McCune-Albright Syndrome.

Aneurysmal bone cysts (ABCs) are defined as benign cystic lesions of bone composed of blood-filled spaces. ABCs may be a secondary pathology superimposed on fibrous dysplasia (FD). Concomitant FD and ABC in relation with McCune-Albright syndrome is an extremely rare condition. Here, we report concomitant, double ABCs in bilateral occipital regions and FD from the skull base to the C2 vertebra with Chiari type 1 malformation. A 14-year-old female with a diagnosis of McCune-Albright syndrome presented with swellings at the back of her head. The lesions were consistent with ABCs and were totally resected with reconstruction of the calvarial defects. The coexistence of FD, bilateral occipital ABCs, and Chiari malformation type 1 in a McCune-Albright patient is an extremely rare condition and, to our knowledge, has not been reported to date. Exact diagnosis and appropriate surgical treatment usually lead to a good outcome.