Archives of the AFIP -- RadioGraphics

Figure 3: Intradiploic epidermoid inclusion cyst with classic radiologic features in a 19-year-old man. Panel A Lateral skull radiograph shows a well-demarcated lytic defect with sclerotic and scalloped margins, suggestive of a slowly expanding mass. Panel B Axial contrast material enhanced CT scan shows an expansile, nonenhancing, intradiploic mass; its attenuation is low but higher than that of fat in the scalp. The inner margin of the mass is formed by a combination of the dura mater and the remodeled inner table of the skull and appears sclerotic and slightly nodular. Panel C Axial T1-weighted MR image shows the ovoid lesion within the diploic space. The mass is hyperintense relative to cerebrospinal fluid. Panel D On the gadolinium-enhanced T1-weighted MR image, the lesion has signal intensity near that of water. Panel E On the T2-weighted MR image, the mass becomes quite bright. Lateral intradiploic epidermoid lesions are usually not associated with any other malformations.

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