Localization of filaggrin in human middle ear cholesteatoma.

Filaggrin, a histidine-rich protein, was located immunohistochemically in human middle ear cholesteatoma by specific antibody. It was found to be localized in the cytoplasm of the granular layer cells and cornified layer. The pattern of distribution is similar to that of epidermis. Filaggrin is a major component of keratohyalin which is a distinct component of the differentiating epidermal cells. Thus the presence of filaggrin in cholesteatoma suggests epidermal characteristics of the cholesteatoma.