Computed tomography of a diploic epidermoid cyst of the skull.

The computed tomographic (CT) and other roentgenological characteristics of a skull diploic epidermoid cyst in a 14-year-old boy with Ito syndrome, a neurocutaneous syndrome, are presented. When this boy was 3 years 10 months of age, a plain roentgenogram of the skull showed an area of decreased density in the left parietal bone. The area has grown for the subsequent 10 years plus and a characteristic sclerotic margin has become evident. CT examination showed a cystic lesion in the diploe, the outer third of high density and the inner third low density. CT allowed prediction of the operative and histological findings. It was useful not only for the diagnosis but also in the pathogenesis.