Immunohistochemical Study for Differentiation of Human Middle Ear Cholesteatoma.

Abstract

BACKGROUND AND OBJECTIVES: Human epidermis is a continuously dividing tissue, in which keratinocytes gradually differentiate and mature while moving from basal cells to suprabasal cell layers. Epidermal homeostasis is maintained by a delicate balance between proliferation and terminal differentiation. Cholesteatoma is characterized by the presence of a squamous epithelium invading the middle ear, which is believed to have hyperproliferative properties. The aim of this study is to determine whether the hyperproliferative character of cholesteatoma is associated with differentiation of basal cell or suprabasal cell layers. MATERIALS AND METHODS: Using immunohistochemical techniques, we investigated the reaction pattern of monoclonal antibody to involucrin and filaggrin as differentiation markers in the cholesteatoma matrices which were harvested during surgery. For the control, the same immunohistochemical study was also done in deep meatal skin and retroauricular skin during the same surgery. RESULTS: The immunostaining intensity of filaggrin at suprabasal cell layers was higher in cholesteatoma than in retroauricular skin and deep meatal skin. The immunostaining intensity of involucrin at suprabasal cell layers was higher in cholesteatoma and deep meatal skin than in retroauricular skin. CONCLUSION: This result represents that the epidermal cells in cholesteatoma at suprabasal layers actively differentiate more than the epidermal cells in retroauricular skin. So this study suggests that hyperkeratinization in cholesteatoma might be due to altered differentiation of suprabasal keratinocytes. Furthermore, this study reveals that the deep meatal skin has unusual hyperproliferative behavior in contrast to the retroauricular skin.