Radiation effects on the external auditory canal.

Radiation is used to treat many head and neck tumors, and of necessity the temporal bone is sometimes included in the paths of radiation. We studied the histopathology of the external auditory canal in 13 temporal bones from 10 patients who had undergone irradiation for head and neck tumors. The pathologic changes noted could be divided into: bony changes, and soft tissue changes. Bony changes manifested were those of resorption, fibrosis, empty lacunae, and sequestration. There were five soft tissue changes: the formation of a secondary cholesteatoma, ulceration of the lining epithelium with resorption of the underlying bone, thickened epithelium in the canal as well as in the tympanic membrane, subepithelial fibrosis, and atrophic ceruminous glands. Clinically these changes can be manifested as a persistent otitis externa, with otorrhea and otalgia.