LAUSR

CT: computed tomography INTRODUCTION Epidermoid cysts are benign and slow-growing lesions that are usually less than 2 cm in diameter and do not affect the overlying skin. Characterized by a stratified squamous epithelial wall, they often feature a central punctum and are freely mobile on palpation. Although relatively common elsewhere in the body, they rarely arise from the central nervous system, with an incidence of 0.2% to 1.8% of all brain tumors. The majority of central nervous system epidermoid cysts are observed in adults, with a mean age of presentation of 40 years. These lesions are thought to arise from inadvertent inclusion of ectodermal elements during neural tube closure, trapping them in the diploe, meninges, scalp, or suture lines. Intradiploic cysts may also occur secondary to trauma. Regardless of the mechanism underlying their formation, central nervous system epidermoid cysts are overwhelmingly intradural and, even when located in the intradiploic space, rarely perforate bone. Here, we present a pediatric case of an intradiploic epidermoid cyst with cranial bone invasion.