Epidermoid cysts of the cranial bones.

Ectodermally derived tissue in ectopic sites is seen in the head and neck. Extracranial dermoid and epidermoid tumors are relatively rare. While most otolaryngologists are familiar with the cholesteatoma of the otic area, not very many are exposed to this lesion in other sites. Those of the cranial bones are even rarer still. These tumors may expand (1) laterally in the cranial bones, (2) externally to present as masses in the scalp or facial region, or (3) internally to involve the intracranial contents. A patient with a frontal bone epidermoid, whose tumor had expanded in all three directions to erode both inner and outer cortex of cranium and laterally to rupture into the frontal sinus, is discussed. The literature is reviewed and the management of these rare masses is discussed.