Epidermal hyperplasia of the tympanic membrane and deep external ear canal: novel histo‐pathological features, embryological and clinical correlates

Abstract

Objectives. To study the histology and developmental biology of epidermis of tympanic membrane and deep ear canal and to correlate the histo‐pathological features with clinical conditions.Method. Histo‐pathological and electron microscopic examination was performed of deep meatal skin, keratosis, keratosis obturans, external canal cholesteatoma, retraction pockets, acquired cholesteatoma and tympanic membrane perforations.Results. In some mature ears, a marked change in the normal flat thin epidermis to one resembling that of the fetus is seen in the presence of local inflammation. This hyperplastic epidermis is present in varying lengths on the tympanic membrane and deep ear canal and displayed as hyperplastic bands growing down into sub‐epidermal tissue and sometimes penetrated the collagen layer of the tympanic membrane to enter the middle ear. Keratosis was frequent on the surfaces of the tympanic membrane and deep ear canal, which may also be found in the invading bands, where they produced small keratin cysts.Conclusions. Severe chronic otitis media, with inflammatory exudates, glandular metaplasia or tympanosclerosis, may be associated with hyperplasia. This type of epidermal hyperplasia appeared to be pathogenic and was observed in several structurally distinct entities such as keratosis, keratosis obturans, retraction pockets, and cholesteatoma of the deep external canal. Invading epidermis in the middle ear, in some cases, is indistinguishable from acquired cholesteatoma. This reverse differentiation highlights a primordial property of auditory epithelium, which was not previously recognised. Furthermore, hyperplastic epidermis appears to be pathogenic and may be the cause of some specific conditions or their complications.References 1 Johnson A., Hawke M., Berger G. (1984) Hodge memorial Award‐surface wrinkles, cell ridges, and desquamation in the external auditory canal. J Otolaryngol.13, 345–3542 Johnson A., Hawke M. (1985) Cell shape in the migratory epidermis of the external auditory canal. J Otolaryngol.14, 273–281