[Aneurysmal bone cyst of the mastoid bone: one case report].

Aneurysmal bone cyst of mastoid bone is seldom, here one case was reported. The mastoid bone of the patient presented with a baloon-like swelling full of non-coagulated blood and serous-hemorrhagic fluid. CT scan demonstrated a large expansile destructive mass located in left mastoid bone region with the thin or absent cortical bone. The MRI demonstrated T2-weighted images and clear boudary from surrounding tissue. Pathologic reported that the mastoid bone was repalcement with lacunar divided by fibro-tissue, containing numerous hemosiderin, giant cells and inflammatory cells. A surgery was performed and the patient was cured.