Hyperproliferative characteristics of Human Middle Ear Cholesteatoma

Abstract

Human epidermis is a continuously dividing tissue, in which the keratinocytes gradually differentiate and mature while moving from the basal cell compartment to the upper cell layers. However, cholesteatoma is characterized by the presence of squamous epithelium invading the middle ear. This epithelium is believed to have hyperproliferative properties. Using immunohistochemical techniques, we investigated the reaction pattern of monoclonal antibody to PCNA and cytokeratin 16 as proliferating markers, and of monoclonal antibody to cytokeratin 13 and DBA as basal cell markers in the cholesteatoma to determine whether the number of proliferating cells is increased, and whether proliferating cells are found beyond the basal cell layer in cholesteatoma. The results were as follows: 1) When the tissues were stained with the proliferating markers PC10 and K8.12, the normal epithelium of ear canal showed focal staining in the basal cell layer, whereas epithelium of cholesteatoma showed dense, diffuse staining not only in the basal cell layer but also in the suprabasal cell layer. 2) When the tissues were stained with the basal cell markers KS-1A3 and DBA, both epithelium of the normal ear canal and of cholesteatoma showed staining in only a single basal cell layer. These results suggest that increased epidermal cell proliferation in cholesteatoma may be due to increased proliferative activity in suprabasal keratinocytes as well as in the basal compartment.