Joint Capsule-Like Intracranial Osteochondroma Mimicking Cystic Meningioma.

This report provides the first representative images of an intracranial osteochondroma with a cystic component mimicking cystic meningioma. A 40-year-old male presented at our outpatient clinic with decreased sensation in his right upper extremity. Preoperative computed tomography showed a tumor with a cystic meningioma-like appearance and prominent calcifications. On magnetic resonance imaging, calcification of the lesion was suggested by the T2-weighted image; weak enhancement was seen on the T1-weighted image. Following surgical removal of the tumor, the pathologic examination showed findings consistent with osteochondroma. Cystic meningioma is a rare tumor with a cystic component. Intracranial osteochondroma is also a rare, benign tumor that can mimic meningioma when presenting in the dural convexity. Our report describes the joint capsule-like appearance of a convex cystic osteochondroma including a calcified cap, bonelike structure, and fluid-containing intracapsular space. The tumor was evaluated by imaging and pathologic studies.