Frontal mucocoele communicating with an arachnoid cyst of the anterior cranial fossa.

Mucocoeles usually involve the frontal sinus and can extend to the orbit or intracranially. In this case symptoms and radiological findings were typical of a left frontal mucocoele with intracranial extension. Intraoperative findings were compatible with a left frontal mucocoele communicating with an arachnoid cyst of the anterior cranial fossa.