Clinical Characteristics of Keratosis Obturans and External Auditory Canal Cholesteatoma

Objective Keratosis obturans (KO) and external auditory canal cholesteatoma (EACC) have been considered separate entities. While the disorders are distinct, they share many overlapping characteristics, making a correct diagnosis difficult. In the present study, we compared their clinical characteristics and radiological features to clarify the diagnostic criteria. Study Design Retrospective case series. Setting Academic medical center. Subjects and Methods The clinical data of 23 cases of EACC and KO were retrospectively reviewed. The following clinical characteristics were compared between the 2 groups: sex, age, onset of symptoms, follow‐up period, audiometric results, and imaging findings on temporal bone computed tomography including bilaterality, location, and the presence of extension to adjacent tissue. Results The mean age of the EACC group was significantly older than that of the KO group. All of the cases of EACC occurred unilaterally, and bilateral occurrences of KO were observed in 4 of 9 cases. All of the lesions in the KO group were circumferential, and no lesion in the EACC group invaded the superior canal wall. No significant differences in symptoms, such as acute otalgia, otorrhea, and hearing loss, were noted between the 2 groups. The incidence of conductive hearing impairment more than 10 dB was higher in the KO group than in the EACC group. Conclusion Thus, KO and EACC are 2 distinct disease entities that share common features in clinical characteristics except for predominant age and bilaterality. Conservative treatment with meticulous cleaning of the lesion was successful in most cases with a long‐term follow‐up.