Bone resorption in chronic otitis media. The role of cholesteatoma, a must or an adjunct?

Abstract

The paper contains the results of light microscopical, electron microscopical and histochemical examinations of chronic otitis media, with and without cholesteatoma, with special focus on the problems regarding bone resorption. It is demonstrated that bone resorption takes place without the presence of cholesteatoma itself, even though the magnitude of resorption is higher in the cases with cholesteatoma. It is demonstrated that there is always a layer of subepithelial granulation tissue between the cholesteatoma membrane and the underlying bone. The picture in the resorbing zone is dominated by mononuclear histiocyte like cells, containing dense cytoplasmatic bodies, called lysosomes, and it is demonstrated that the marker enzyme for acid hydrolases, the acid phosphatase, is present in large quantities, both in the histiocytes, as well as spread along the bony surface. It is concluded that a possible mechanism for bone resorption is performed by the acid hydrolases, contained in the histiocytes, working at acid pH. It is noteworthy that the multinucleated osteoclast is not demonstrated in the resorbing margin of bone and that the picture is dominated by capillary proliferation, indicating that ischemia does not play a role in bone resorption. On the contrary, this is in the author's opinion caused by inflammation and hyperemia. The various factors influencing bone resorption in general and in chronic otitis media are discussed and a new model for studying cholesteatoma pathology in the middle ear is presented.