ABSTRACT
Dermoid cysts are congenital cysts that result from sequestration of ectodermal and mesodermal elements. They occur along lines of embryologic closure, and the external angle of the supraorbital ridge is the most common site. External angular dermoid cysts are situated beneath the muscle and lie in a shallow depression in the outer table of the bone of the skull. A ‘pit’ within the bone is invariably present in the base of the bony depression through which the cyst receives its blood supply. Occasionally these cysts have an intracranial extension in a ‘dumb-bell’ fashion, although this is far less common than with dermoid cysts situated at the internal angle of the eye or over the bridge of the nose.
