Junctions of squamous epithelium with middle ear mucosa.

Specimens obtained from the middle ear during surgery for cholesteatoma showed either abrupt junctions without metaplasia or junctions of varying width with metaplastic epithelium. Another form of junctional area showed pronounced inflammatory cell reaction with squamous epithelium projections growing into the stroma under the columnar epithelium. Immunofluorescent staining for cytokeratins showed distinct decoration of the columnar and metaplastic epithelia as well as of the basal cells of squamous epithelium. Prekeratin staining showed decoration of both squamous and metaplastic epithelium and no staining of the columnar epithelium. The findings suggest that metaplasia forms part of the migrating front of the squamous epithelium and alone plays no major role in cholesteatoma genesis.