Melanotic intracranial epidermoid: Case report and description of a new subtype

Intracranial epidermoids are generally seen as hypodense nonenhancing lesions on computed tomography scans; and, as T1 hypointense and T2 hyperintense lesions on magnetic resonance imaging (MRI). Unusual radiological findings have been reported earlier. The authors present the case of a 54-year old male patient who had prior intracranial surgery. On MRI, there was a thick peripheral mantle of diffusion restriction with a central core of brilliant T1 hyperintensity and very black T2 hypointensity. The peripheral mantle showing diffusion restriction was heterogeneously T1 hypointense and T2 hyperintense. At surgery, there was a typical pearly white epidermoid peripherally with a greenish-brown centre. Pathology showed abundant extracellular melanin which was also found in the basal layer. The authors present the first case of a melanin pigmented intracranial epidermoid in literature, describing a new histological subtype.