Frontal sinus mucocele with intracranial extension associated with osteoma in the anterior cranial fossa.

A 70-year-old man presented with a rare case of paranasal osteoma with secondary mucocele extending intracranially, manifesting as a generalized convulsion. Computed tomography showed a large calcified tumor adjacent to the cystic mass in the left frontal lobe. He underwent left frontal craniotomy, and the cystic lesion was totally removed. Histological examination confirmed the diagnosis of osteoma and mucocele. The giant paranasal sinus osteoma prevented growth of the mucocele into orbital recess and extension into the orbital space and paranasal sinus. The mucocele disrupted the dura in the anterior cranial fossa, resulting in a giant cystic intracranial lesion. Frontal osteoplastic craniotomy was effective for exposing both lesions and plastic repair of the dural perforation to prevent cerebrospinal fluid leakage and secondary infection.