The Metaplastic and Congenital Origin of Cholesteatoma

Abstract

Nineteen out of 101 biopsies taken from cholesteatomatous ears showed in the subepithelial inflamed connective tissue small or large aggregates of keratin fibres surrounded by special cells. The larger aggregates were similar to epidermoid cysts. All these biopsies also contained mucus glands. The fibres were identified as keratin by their morphological features, birefringence and specific immuno-horseradish peroxidase reaction. The cells surrounding the keratin fibres 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 centres with the surface epithelium. We interpret these findings to 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. Of especial interest is our finding that cells of normal middle ear and Eustachian tube lining contain small amounts of intra-cellular keratin—as a non-pathological phenomenon—conforming to recent findings of most epithelial cells of the mammalian body (bronchia, pancreas, etc.). We would also like to suggest that it is this process which may be responsible for primary (the so-called‘congenital’) cholesteatomas, as well as recurrence of epidermoid cysts in operated choles-teatomatous ears, i.e., the so-called‘residual disease’. It also seems likely that quite a few congenital cholesteatomas do, with time, perforate silently—and present themselves later as an ordinary cholesteatoma. Therefore, while the aural cholesteatoma has more than one 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.