Int. Adv. Otol. 2009; 5(3); 294-300

Tympanic epidermosis: A noncholesteatomatous keratinizing entity of chronic otitis media
Patrice Tran Ba Huy, Romain E Kania, Rania Benhamed, Michel Wassef, Charlotte Hautefort  

Department of Otorhinolaryngolaryngology-Head and Neck Surgery, Assistance Publique Hôpitaux de Paris, Hôpital Lariboisière, Paris, Université Paris 7
Paris Diderot and LNRS, CNRS 7060, romain.kania@lrb.aphp.fr

Objective: Keratin in the middle ear cavity is usually associated with the diagnosis of cholesteatoma currently explained by 3
mechanisms in the literature: retraction, squamous metaplasia and immigration. But different pathogenetic mechanisms cannot
result in the same disease. The objective of this study is to show that immigration of the keratinizing epithelium of the tympanic
membrane into the middle ear yields a specific entity, tympanic epidermosis.

Materials: Retrospective study of 34 patients referred for “cholesteatoma”.

Results: Otoscopic findings were mesotympanic perforation lining the malleus handle, keratin surrounding the handle of the
malleus and accumulating into the mesotympanum with no limiting matrix, and tympanic remnants opaque and whitish.
Histopathology of the tympanic remnants revealed a preserved intermediate fibrous layer lined on both sides by a thin
keratinized squamous epithelium. Computed tomography revealed well-ventilated posterior cavities.

Conclusions: Epidemiologic, clinical, pathogenetic, and histopathologic features suggest that immigration of keratinizing
epithelium through a mesotympanic perforation results in the clinical condition tympanic epidermosis, which is strikingly
different from cholesteatoma and squamous metaplasia. Retraction, metaplasia and immigration processes yield different
pathological entities that should be clearly identified, because they do not share the same evolution or require the same
therapeutic management.