[Cell adhesion proteins in external auditory canal cholesteatoma]

External auditory canal cholesteatoma (EACC) is a rare entity in otolaryngology, which is histomorphologically identical with middle ear cholesteatoma. The cause of EACCt is, however, still not clear. The aim of this study was to describe the expression of beta-catenin, MMP-2, and MMP-9 in EACC matrix compared to the normal auditory meatal skin (AMS).

Thirteen specimens were obtained during surgical procedure. EACC and AMS specimens were immunostained with antibodies for beta-catenin, MMP-2, and MMP-9.

Only the basal layers of the EACC specimens were positive for beta-catenin. The suprabasal layers showed diminished or negative immunostaining for beta-catenin. In all layers, AMS was homogeneously positive for beta-catenin. In contrast, the immunostaining for the gelatinases was equally increased in all layers of EACC, whereas AMS was weekly positive.

The reduced immunoreactivity for beta-catenin may have been present because of the lessened cell-cell adhesion in the suprabasal layers of EACC. The increased expression of the metalloproteinases might point at an increased lack of integrity of EACC matrix. Recent studies revealed a balance between disintegrating and stabilising factors in normal tissue, which is disturbed in inflamed and neoplastic tissue. In EACC matrix, an imbalance of these factors, represented by reduced beta-catenin and increased gelatinase expression, is possible. Increased desquamation, the accumulation of keratin debris, and loss of tissue-stability support our findings.