Nationwide survey of congenital cholesteatoma using staging and classification criteria for middle ear cholesteatoma proposed by the Japan Otological Society

Objective: This study was undertaken to determine the characteristics of congenital cholesteatoma (CC) in Japan, via a nationwide survey using staging and classification criteria for middle ear cholesteatoma, as proposed by the Japan Otological Society (JOS). Methods: A nationwide survey regarding middle ear cholesteatoma treated in 2015 was performed. There were 1787 registrations from 74 facilities, among which, CC accounted for 12.9% (231 cases) of all middle ear cholesteatoma cases. The extent of the disease was classified according to the classification and staging of cholesteatoma proposed by JOS in 2015. Results: The age of the patients ranged from 1 to 55 years (mean, 8.2 years; median, 6 years; 149 ears of males; 82 ears of females). Among these cases, 105 (45.5%) were classified as stage I, 121 (52.4%) as stage II, and 5 (2.1%) as stage III, with no cases in stage IV. In the sub classification of stage I, 35 (33%), 43 (41%) and 27 (26%) ears were classified as stages I-a, I-b and I-c, respectively. Stage I-b (cholesteatoma confined to the posterior half of the tympanic cavity) was more frequent than stage I-a (the anterior half of tympanic cavity). Pre-operative hearing level of air-conduction was 20.5 dB for stage I-a, 34.5 dB for stage I-b, 30.5 dB for stage I-c, 38.6 dB for stage II, and 59.0 dB for stage III. The rate of missing stapes superstructure increased as the disease progressed. In the same way, the mastoid development lowered as the stage of the disease progressed. There were significant differences in the age at operation, pre-operative hearing level, status of stapes, and major ossiculoplasty, between stage l-a and l-b. Conclusions: The current condition of CC in Japan was been evaluated; in particular, it was observed that the cases limited to the posterior part of tympanic cavity were not rare. The JOS stage classification based on the progression of the disease seemed simple and efficient.