[Mallear epidermosis. An unusual form of open mucous otitis].

The presence of keratin in the middle ear cavity is usually associated with the diagnosis of cholesteatoma or epidermoid metaplasia. Analysis of a series of 18 cases suggests that it may correspond to a specific entity developing in the course of severe or long-lasting opened chronic otitis. This condition, we called mallear epidermosis, is characterized by: i) a perforation of the tympanic membrane lining the handle of the malleus and the umbo; ii) a proliferation of keratin surrounding the handle of the malleus and diffusing into the mesotympanum on the internal side of the tympanic membrane, without matrix; and iii) a mild inflammation of the middle ear epithelium. The process is usually limited to the mesotympanum and does not extend towards the attic and the posterior cavities. Epidemiological, clinical, pathophysiological, and histological features allow this entity to be distinguished from cholesteatoma and epidermoid metaplasia. Management is either medical consisting of local treatment and microaspiration, or surgical including resection of the umbo, removal of the tympanic membrane invaded by the adherent hyperkeratotic layers and repair by conventional underlay myringoplasty. This report emphasizes the need for a clear identification of the various types of chronic otitis media presenting with keratin in the middle ear, as they do not share the same course and do not require the same therapeutic management.