[Immunohistochemical study of the epithelial hyperproliferation in middle ear cholesteatoma]

To elucidate the role of epidermal growth factor (EGF) in the growth of cholesteatoma, and to investigate the biological behaviour of cholesteatoma.

The expression of EGF receptor (EGFR), proliferating cell nuclear antigen Ki-67, collagen IV protein and laminin in 18 specimens of cholesteatoma was stained immunohistochemically and compared with that in epidermis of 8 specimens of normal external auditory meatus skin.

The immunostaining for EGFR showed two patterns: strong linear or granular cell surface staining and granular cytoplasmic staining. In epidermis of normal skin, EGFR appear to be highly expressed on the basal layer. Cholesteatoma epithelium showed increased positive reactions in the super basal layers. The Ki67 was expressed in nuclei, and a dot-like as well as a diffuse nuclear staining pattern was detected. The Ki67 expression was restricted in the basal layer of normal epithelium, and the positive of Ki67 in nuclei was rare. The expression of Ki67 in cholesteatoma extended to the suprabasal and upper layers of the epithelium with an increasing frequency of positive cells. Collagen IV and Laminin were similary localized in the basement membrane of normal epithelium with a continuously staining pattern and a similar staining pattern was also found in the cholesteatoma, and the vas is abundant under basement membrane in some cholesteatoma samples.

The overexpression of EGFR suggest a hyperproliferative state in cholesteatoma and there is a close relationship between the EGF and hyperproliferation of cholesteatoma. The increased expression of Ki67 confirms the hyperproliferative nature of cholesteatoma. The results of expression of Collagen IV and Laminin in cholesteatoma indicate it is a benign disease.