The role of bone resorption in the etiopathogenesis of acquired middle ear cholesteatoma
Cholesteatoma is a destructive disease characterized by the progressive expansion of keratinizing squamous epithelium in the middle ear and mastoid, and chronic inflammatory reaction of the subepithelial connective tissue. N-Acetyl-β-d-hexosaminidase (HEX) catalyzes the release of terminal non-reducing N-acetyl-d-hexosamine residues acting on glucosides and galactosides in glycoproteins, GM2-gangliosides and glycosaminoglycans (GAGs). In this study the activities of HEX were measured in cholesteatoma tissue and in normal skin to demonstrate a possible role of HEX in bone resorption in the area adjacent to cholesteatoma. Cholesteatomas (n = 21) and normal adult retroauricular skin (controls, n = 21), were collected from patients during surgery due to chronic otitis media. In 20 of 21 specimens a significantly higher activity of HEX was observed in cholesteatoma tissue compared with that in normal skin. Mean release of HEX from the activated cells was 68.55 ± 30.77 nkat/g wet tissue in cholesteatoma and 31.79 ± 10.02 nkat/g wet tissue in skin specimens. It may explain the process of bone resorption in the area adjacent to cholesteatoma, i.e. ossicles or temporal bone. This study suggests that drugs inhibiting HEX activity, such as iminocyclitols, may be useful in cholesteatoma treatment.