Posttraumatic intradiploic epidermoid cyst of frontal bone

Intracranial epidermoid cysts constitute about 1% of all intracranial tumors. They are usually congenital in origin and are thought to derive from ectodermal cell inclusions occurring during closure of the neural tube. Twenty-five percent of these are found in the skull as intradiploic epidermoid cysts. These intradiploic cysts are usually congenital, slow growing, and can grow to large size without causing symptoms. We present a case of intradiploic epidermoid cyst of frontal bone developed due to childhood trauma. The cyst expanded and eroded the walls of the frontal sinus causing proptosis, diplopia, and restricted eye movements with frontal headache. The bicoronal flap approach was used for complete removal of the cyst. Complete removal of the cyst wall is necessary to avoid recurrence.