Pathogenesis of attic cholesteatoma: Clinical and immunohistochemical support for combination of retraction theory and proliferation theory

Objective: The aim of the current study was to provide support for a combin ation of the retraction and proliferation theories of acquired cholesteatom a. Background: There is clinical evidence for formation of a retraction, but t here is a lack of explanation for the transition from a retraction pocket t o an active and expanding attic cholesteatoma. Methods: Epidemiologic studies on the incidence of attic retractions and fo llow-up studies on patients with attic retractions were performed. Addition ally, expression of proliferation marker and analysis of basement membrane were studied in samples of attic cholesteatoma. Results: The prevalence of attic retractions was between 14% and 25% of inv estigated ears. In children with manifest secretory otitis, there were some attic cholesteatomas and 5% to 6% severe retractions. Some of them became precholesteatomas, requiring treatment and controls. Immunohistochemistry o f attic cholesteatomas showed that proliferating keratinocytes were very of ten seen within epithelial cones growing toward the underlying stroma. Thes e growth cones exhibited focal discontinuities of the basement membrane, es pecially in areas of intense subepithelial inflammation. Conclusions: As a possible explanation based on clinical and immunohistoche mical findings, the authors propose a four-step concept for the pathogenesi s of cholesteatoma that combines the retraction and proliferation theories: (a) the retraction pocket stage; (b) the proliferation stage of the retrac tion pocket, subdivided into cone formation and cone fusion: (c) the expans ion stage of attic cholesteatoma; and (d) bone resorption.