A giant intradiploic epidermoid cyst with perforation of the dura and brain parenchymal involvement.

A patient with a long-standing intradiploic epidermoid cyst with perforation of the dura and brain parenchymal involvement is reported. A 69-year-old man, who had previously presented with a subcutaneous mass on the left frontoparietal scalp, developed a sudden grand mal seizure. Magnetic resonance imaging showed a well-defined mass in the frontoparietal scalp with destruction of the skull. Penetration of the dura allowed for communication with the intracranial structures. Surgical resection and cranioplasty were performed. There were no well-defined margins in the deep portion and the mass was subtotally removed. Histological examination showed that the cystic structure was lined by squamous epithelium containing laminated keratin material. The pathologic findings were consistent with the diagnosis of an epidermoid cyst.