[Immunohistochemical studies of vascularization of cholesteatoma]

Middle ear cholesteatoma is characterised by the presence of a stratified squamous epithelium with keratin depositions in the middle ear cavity. The vascularisation of the stroma of cholesteatoma was examined using a monoclonal antibody against human factor VIII related antigen as an endothelial cell marker. Normal aural skin sections were stained for comparison. The vascularisation was frequently more numerous in the stroma of cholesteatoma than in normal skin. It was generally noted that the morphology of the blood vessels differed between both clinical types of cholesteatoma. Furthermore, the number of transforming growth factor-alpha positive cells was found to be increased in the stroma of cholesteatoma. In the surroundings of the blood vessels an abundant infiltration of macrophages was observed. Macrophages are known to produce significant amounts of transforming growth factor-alpha. Therefore, hypervascularization could be induced by enhanced expression of growth factors from activated immune cells in the stroma of cholesteatoma and could substantially contribute to the unrestricted abnormal growth of cholesteatoma.