Introduction: Extradural intradiploic epidermoid cysts are rare, representing less than 0.25% of all primary intracranial tumors. They can be neurologically silent and can only present psychiatric symptoms like depression, cognitive or personality changes.
Case outline: A 68-year-old male with two year long history of depressive mood, lack of motivation, helplessness, hopelessness and poor response to antidepressive drug therapy was described. CT scan showed a well-defined mass in the parietal scalp with destruction of the scull. He underwent intracranial tumor resection. Surgical resection and cranioplasty were performed. Pathology confirmed intradiploic epidermoid cyst.
Conclusion: Total removal of these cysts and repeated washing of the cavity with 0.9% saline may prevent recurrence and aseptic meningitis and may improve mental state of the patient. We also emphasize the need for neuroimaging studies in a patient with atypical changes in mental status, even without neurological signs or symptoms.