Biomolecular characteristics of cholesteatomas

• Grant number: 08/08188-0
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2008
• End date: September 30, 2009
• Field of knowledge: Health Sciences - Medicine - Surgery
• Principal Investigator: Fernando de Andrade Quintanilha Ribeiro
• Grantee: Fernando de Andrade Quintanilha Ribeiro
• Host Institution: Faculdade de Ciências Médicas da Santa Casa de São Paulo (FCMSCSP). Fundação Arnaldo Vieira de Carvalho. São Paulo , SP, Brazil

Abstract

Cholesteatomas are characterized by the hyperproliferation of the keratinocytes of the epidermis, causing erosion of the adjacent bones. The migration of skin of the external auditory meatus through the interior of the tympanic ear cavity characterizes cholesteatoma of the middle ear. This migration can occur for aspiration of the "pars flaccida" of the tympanic membrane (primary cholesteatoma) or through a previous perforation of this membrane (secondary cholesteatoma). There is also the congenital cholesteatoma, this type is rare and elapses of the growth of epithelial remaining portions that had remained in the timpanic cavity during the embryologic development. Clinically we notice that, in similar conditions, not all individuals develop cholesteatoma. Moreover, this illness can be disclosed of different forms, related to the degree of epithelium migration, the onset of adjacent bone structures and aggression. Infection occurs frequently as much as erosion of middle ear bones, causing serious complications, such as deafness, facial palsy, cerebral abscesses and meningitis. Recent studies demonstrate that the migration, proliferation and aggression caused by this epithelium are specific characteristics of the keratinocytes that constitute cholesteatoma. Many of these characteristics had been observed in epithelial cells of the medial portion of the external auditory meatus. The presence of cytokeratin 16 (intermediate filament presents in the cytoplasm of hyperproliferative cells) in this place, under the influence of inflammatory cytokines, would cause the migration of this epithelium through the interior of the middle ear cavity in predisposed individuals. These findings can be evidenced in cholesteatomas of the external auditory meatus, which skin, apparently normal, eroded spontaneously the adjacent bones, with similar complications as cholesteatoma of the middle ear. (AU)