CYTOKERATIN 16 EXPRESSION DOES NOT INDICATE CHOLESTEATOMA AGGRESSIVENESS.

Aims: Cholesteatoma is characterised by a squamous epithelium in the middle ear and aggressive destructive behavior. A hyperproliferative epithelium also typically has an overexpression of cytokeratin 16 (CK16). The aim of this study was to compare CK16 expression in cholesteatoma epithelium and the epithelium of simple dry perforations. Methods: Samples were obtained from 60 patients: 30 with cholesteatoma and 30 with simple perforations. The epithelium was immunohistochemically stained for CK16. Correlations were made between the clinical picture and the absence or presence of complications in both groups. Results: Immunohistochemical staining for CK16 was positive in 45% of specimens taken from the edge of simple perforations and in 51% of specimens taken from the cholesteatoma matrix. The difference was not statistically significant. Conclusion: Two implications of our findings may be suggested: in cases of cholesteatoma the change in CK expression from normal epithelium is not the only factor which makes cholesteatoma aggressive; alternatively, in normal tissue the edge of a simple perforation is not as stable as is thought so that at least 45% of perforations can show hyperproliferative activity. It is therefore unclear whether hyperproliferative activity in either cholesteatoma or a simple perforation is a marker of instability or of attempts at healing. [ABSTRACT FROM AUTHOR]