ANTIGEN EXPRESSION OF EPITHELIAL MARKERS, COLLAGEN-IV AND COLLAGEN-KI67 IN MIDDLE-EAR CHOLESTEATOMA - AN IMMUNOHISTOCHEMICAL STUDY

The expression of epithelial markers (cytokeratins, Filaggrin, BerEp4 and EMA), collagen IV and Ki67 was studied immunohistochemically in ch olesteatoma and compared with that in epidermis of meatal skin, squamo us epithelium of eardrum and simple epithelium of middle ear mucosa. M NF116 (cytokeratin 10, 17, 18) stained the full layer of normal epithe lium and all cholesteatoma specimens. CK10 and Filaggrin were expresse d in the upper layer of epidermis but more diffusely in cholesteatoma. BerEp4 was found in the basal layer of normal epithelium but was dete cted in most epithelial cells in cholesteatoma matrix. Variability was observed in EMA and CK14 immunostaining. Collagen IV was localized in the basement membrane of normal epithelium with a continuously staini ng pattern, an observation also made in the cholesteatomas studied. Ho wever, in one of these small areas the basement membrane was not stain ed with collagen IV. Ki67 was expressed in nuclei of the cells in the basal layer of normal epithelium but extended to epithelial cells in t he upper layers of cholesteatoma matrix. The results of the present st udy indicate that the expression pattern of epithelial markers in chol esteatoma corresponds to that in normal epidermis. The increasing expr ession of BerEp4 and Ki67 confirms the hyperproliferative nature of ch olesteatoma. Whether or not the lack of expression of collagen IV in o ne of the cholesteatomas reflects a true degradation of the basement m embrane needs further investigation in extended materials.