SQUAMOUS METAPLASIA OF THE MIDDLE-EAR EPITHELIUM

This study deals with the expression of cytokeratins (Cks) in squamous cell metaplastic lesions in rat and human middle ear. In rats, squamo us metaplastic lesions could be induced during chronic otitis media. T he histological features of these lesions were similar to those observ ed in the human middle ear. Immunohistochemistry revealed that squamou s cell metaplasia in both rat and human middle ear is characterised by a loss of simple epithelial cell related Cks and the appearance of Ck s characteristic of stratified and cornifying epithelia. This indicate s a true change in the differentiation of the middle ear epithelium. I t is concluded that the Ck profile of the cholesteatoma matrix cannot be used as a variable to decide whether the origin of cholesteatomas i s epidermal or metaplastic. This rat model is suitable for studying sq uamous cell metaplasia in relation to cholesteatoma genesis.