Learning Objectives: JOS staging system is efficient for understanding the pathgenesis of cholesteatoma. In general, regular follow-up is required for at least 10 years post-operatively to identify the formation of cholesteatoma recurrence.

Introduction: Japan Otological Society (JOS) proposed the original staging system for the intra-operative extension of cholesteatoma around the tympano-mastoid cavity at this meeting. In the present study, first we defined the types of cholesteatoma as follows: pars flaccida, pars tensa, congenital and secondary. Using JOS staging system, then we reviewed our cases with primary acquired cholesteatoma recently experienced in Nara Medical University Hospital.

Patients and methods: A prospective study of patients with primary acquired cholesteatoma was conducted from January 2011 to September 2014. One hundred and two cases were enrolled and followed-up for a median period of 30 months (range: 12–67 months). We examined the relationship between extension of cholesteatoma according to JOS staging system and surgical results of hearing outcomes and recurrence rates.

Results and conclusion: Hearing improvement in all the subjects with pars flaccida cholesteatoma was 60.6 % (n = 71) and that with pars tensa 44.4% (n = 9). Two cases of recurrence were seen in pars flaccida and also two in unclassifiable cases (range: 18–42 months).