External auditory canal cholesteatoma in patients given radiotherapy for nasopharyngeal carcinoma.

Abstract

Patients who undergo radiotherapy (RT) for nasopharyngeal carcinoma (NPC) may develop external auditory canal cholesteatoma (EACC). The records of patients with newly diagnosed NPC who had received concomitant chemotherapy and RT in a tertiary referral center from 1997 January to 2012 July were retrospectively reviewed. RT-related external auditory canal cholesteatoma (RT-related EACC) was identified in 15 of 833 patients given RT for NPC. Three patients had EACC in both ears. The interval from completion of RT to the diagnosis of EACC ranged from 0.5 to 15.4 years (mean, 5.6 years). RT-related EACC commonly (75%) invaded the anterior and inferior parts of the external canal wall. Canaloplasty was used in 12 patients to surgically remove cholesteatoma. There was no recurrence of RT-related EACC during the study period. Patients with NPC might contract RT-related EACC a few years after RT. We hypothesize that a fraction dose of 200 cGy or more induces RT-related EACC.