Pattern of cholesteatomas under a scanning electron microscope - a risk factor for bone resorption.

OBJECTIVE: The damaging effect of cholesteatomas presents mainly as bone resorption by osteoclasts located in the space between the bone and perimatrix. This process is initiated by the molecular cascade of osteoclast differentiation factors. The aim of the study is to analyse cholesteatoma microstructures via scanning electron microscope (SEM), and associate them with risk and grade of bone erosion.

METHODS: Pathological middle ear tissue fragments with cholesteatoma visible under a microscope were collected from 58 patients operated on for chronic otitis media with features of bone defects in the middle ear walls. These fragments were examined under a scanning electron microscope.

RESULTS: Analysis of the cholesteatomas' surface under a SEM revealed both regular and irregular structure of the matrix, most being the latter. Irregular matrix structures were observed in cases with a short disease history and in patients for whom this was the first surgical procedure. In our analysis, a cholesteatoma matrix with regular structures was associated with less bone destruction of the middle ear space.

CONCLUSIONS: The microstructure of cholesteatomas that showed regular layers under SEM coincides with reduced destruction of the middle ear bone walls. An irregular structure (pathognomonic for a process with a short medical history, and in patients operated on for the first time) is characterised by a tendency towards deeper destruction of bone tissue.