[Immunohistochemical studies with middle ear mucosal remnants in cholesteatoma]

The development of a middle ear cholesteatoma is usually associated with chronic inflammation and displacement of the mucosa present by the invading squamous epithelium. To analyze the clinically different behaviors of both epithelia, we used immunohistochemical methods to study the distribution and expression of interleukin-1 (Il-1), transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), epidermal growth factor-receptor (EGF-R), the proliferation marker MIB 1, c-myc proto-oncogene product and activation marker 4F2. Results stromal that keratinocytes in a cholesteatoma exhibited a much higher activation and proliferation rate when compared to middle ear mucosa cells. Middle ear epithelial cells showed no immunoreactivity for TGF-alpha, EGF-R, Il-1 and c-myc in contrast to the markedly positive immunoreactivity found in cholesteatoma matrix. The local release of cytokines and growth factors, such as TGF-alpha, EGF and Il-1 by inflammatory cells seems to be an important factor for the hyper-proliferative behavior of cholesteatoma epithelium. Our findings could contribute to the pathogenesis of middle ear cholesteatoma and give a possible explanation for the sustained progression of its growth leading to displacement of the middle ear mucosa.