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

Abstract

Objective: The aim of the current study was to provide support for a combination of the retraction and proliferation theories of acquired cholesteatoma.

Background: There is clinical evidence for formation of a retraction, but there is a lack of explanation for the transition from a retraction pocket to an active and expanding attic cholesteatoma.

Methods: Epidemiologic studies on the incidence of attic retractions and follow-up studies on patients with attic retractions were performed. Additionally, 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 investigated 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 of attic cholesteatomas showed that proliferating keratinocytes were very often seen within epithelial cones growing toward the underlying stroma. These growth cones exhibited focal discontinuities of the basement membrane, especially in areas of intense subepithelial inflammation.

Conclusions: As a possible explanation based on clinical and immunohistochemical findings, the authors propose a four-step concept for the pathogenesis of cholesteatoma that combines the retraction and proliferation theories: (a) the retraction pocket stage; (b) the proliferation stage of the retraction pocket, subdivided into cone formation and cone fusion; (c) the expansion stage of attic cholesteatoma; and (d) bone resorption.