Primary and secondary keratomas of the frontal sinus.

Keratomas in the paranasal sinuses have been described in the world literature with variable frequency and the inaccurate terminology of cholesteatoma. This paper describes an illustrative case and provides a discussion of the etiology and pathology of this disease. Because the pathologic findings are that of a true keratoma, classification of this disease as primary and secondary keratomas is recommended. The classification 1. primary keratoma is recommended for the epidermal cyst of congenital rest origin and 2. secondary keratoma is suggested for epithelial layers and cysts that are secondary to squamous cell implantation or migrations.