The etiology of keratosis obturans remains unclear. The self cleansing mechanism of the external ear canal is the net result of the finely coordinated processes of keratin maturation and lateral cell migration. In keratosis obturans, this mechanism is nonfunctional. It appears, however, that there is an increased rate of desquamation of the epithelial cells within the deep canal and a failure in the normal outward migration of these epithelial cells from the surface of the tympanic membrane along the external canal. The canal is occluded by a plug of white keratin debris which contains a small amount of normal appearing brown cerumen in its center.