CLINICAL AND BIOCHEMICAL-STUDIES OF BONE DESTRUCTION IN CHOLESTEATOMA

The exact causative factor(s) of bone erosion in cholesteatoma are not known. In recent pears, the possible role of cytokines has drawn atte ntion. Since the studies on cytokines in cholesteatoma are limited and depend on histopathological methods, the present work approached this subject by biochemical determination of TNF-alpha lysosomal enzymes, acid phosphatase (total and tartrate resistant), cathepsin B, leucyl a minopeptidase lysozyme together with non-lysosomal enzymes calpain I a nd II in 50 cholesteatoma samples (epithelial and subepithelial tissue s) in comparison with 14 normal skin samples from the external ear can al. The study revealed significantly increased levels of all previous indices in cholesteatoma epithelium and subepithelial tissues compared with healthy skin. The levels of these indices reflected the clinical severity of the disease as reflected by their significant increase in cases with erosion of two or three ossicles, erosion of dural plate, sinus plate and facial canal and more extensive cholesteatoma. It is l ikely that TNF-alpha acts both directly by causing bone erosion and in directly by stimulating the release of lysosomal enzymes. The latter m echanism is supported by the significant correlations observed between TNF-alpha. and lysosomal enzymes. The non-lysosomal enzymes calpain I and II seem to participate in the bone erosion associated with choles teatoma by their involvement in collagen destruction. Due to the sugge sted role of TNF-alpha in bone destruction associated with cholesteato ma the use of anti-inflammatory drugs should be taken into considerati on in otitis media to diminish bone destruction. Similarly, antibiotic s should be used to prevent the deleterious effects of bacterial endot oxin.