A histopathologic review of temporal bone exostoses and osteomata.

It is widely accepted that external auditory canal exostoses and osteomata are separate clinical entities that differ in their gross appearance. Disagreement still exists as to whether external auditory canal exostoses and osteomata should be considered similar or separate histopathologic entities. A chart review was performed of all patients who had external auditory canal exostoses or temporal bone osteomata excised from January 1991 to November 1994 at St. Vincent's Hospital, Sydney. A histologic examination was undertaken with a blind study method of the patients whose pathological specimens were suitable for assessment. Eight exostoses and five osteomata were available for examination. The results of this study demonstrate that exostoses and osteomata of the external auditory canal cannot be reliably differentiated by routine histopathological examination.