Cell proliferation and apoptosis in human middle ear cholesteatoma

Objective: To compare the pattern of proliferation and apoptotic cell death in cholesteatoma tissues with that in normal skin. Participants: The cholesteatoma tissue samples were excised from 10 patients during surgery. Normal skin specimens collected from the external ear canal of 6 of the 10 patients were used as controls. Results: In all cholesteatoma tissue samples, apoptotic cells were not seen in the basal cell layer, but they were observed in the suprabasal, prickle, and granular cell layers. In skin specimens obtained from normal external ear canal skin, in which the suprabasal cell layer was comparatively small, similar kinetics of apoptotic cell death were observed. Immunohistochemical analysis using a monoclonal antibody to proliferation cell nuclear antigen demonstrated the presence of proliferating cells in the basal and suprabasal cell layers of the normal external ear canal skin, whereas in the cholesteatoma tissue samples, large numbers of proliferation cell nuclear antigen-positive cells were also observed in the prickle and granular cell layers. Conclusions: Proliferation in cholesteatoma epidermal cells is not uncontrolled, as it is in malignant tumors. Our results demonstrate an increase in the rate of proliferation and apoptotic cell death in cholesteatoma epidermis.