Necrosis and sequestration in the tympanic part of the temporal bone.

Unilateral ulceration, bone necrosis, and sequestrum formation in the external auditory meatus are at times confused with the general diagnosis of keratosis obturans. However, the clinical presentation and the radiological and pathological characteristics of this condition are quite distinct from the latter. Initial examination in this situation may raise the suspicion of malignancy. When a true cholesteatoma of the external auditory meatus is found in association with this entity, according to a review of the available literature and personal observation of the authors, it is the result rather than the cause of this pathological process. In order to clarify this relationship, three patients are presented in whom there is radiological and histological evidence of bone necrosis and sequestration of a segment of the temporal bone but no evidence of hyperkeratosis in the ear canal.