Artificial eustachian tube-induced keratin foreign-body granuloma.

The pathogenesis of granulation tissue that arises periodically around artificial Eustachian tubes was elucidated by histologic examination of 15 cases of tube granuloma. All cases showed the presence of a keratin foreign-body granuloma. The implanted squames incited a foreign-body type of granulomatous reaction and produced a friable vascular exuberant mass that surrounded the artificial Eustachian tube. Histologically, the tube granuloma was characterized by the presence of irregular ovoid slit-like spaces that contained keratin squames, and it was surrounded by foreign-body giant cells.