The Metaplastic and Congenital Origin of Cholesteatoma

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Abstract
Out of 101 biopsies taken from cholesteatomatous ears (human), 19 showed in the subepithelial inflamed connective tissue small or large aggregates of keratin fibers surrounded by special cells. The larger aggregates were similar to epidermoid cysts. All these biopsies also contained mucus glands. The fibers were identified as keratin by their morphological features, birefringence and specific immunohorseradish peroxidase reaction. The cells surrounding the keratin fibers also stained positive to keratin, suggesting synthesis or phagocytosis. Three ossicles contained the above keratin-containing structures in their vascular spaces. Serial sections excluded any connection of the described keratin and mucus-producing centers with the surface epithelium. These findings may be an expression of middle ear mucosa metaplasia. Such subsurface squamous and glandular metaplasia does occur frequently on the surface of the middle ear lining, as described previously. Cells of normal middle ear and Eustachian tube lining contained small amounts of intracellular keratin, as a nonpathological phenomenon, conforming to recent findings of most epithelial cells of the mammalian body (bronchia, pancreas, etc.). This process may be responsible for primary (the so-called genital) cholesteatomas, as well as recurrence of epidermoid cysts in operated cholesteatomatous ears, i.e., the so-called residual disease. A few congenital cholesteatomas do, with time, perforate silently, and present themselves later as an ordinary cholesteatoma. While the aural cholesteatoma has more than 1 origin (retraction pocket cholesteatoma, implantation and possibly migration), primary cholesteatomas originating in the middle ear by a metaplastic process are probably more common than usually recognized.

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