実験的骨破壊における皮膚のうの役割 中耳真珠しゅとの関係について

Abstract

In the present study, we used animal models to induce chronic inflammatory bone resorption which was associated with or without development of skin cysts in order to understand the pricise role of the skin to born resorption in middle ear cholesteatomas. The following tissues were implanted subcutaneously in the back of a total of 60 rats.Group 1: Fresh cortical cochlea wall bone alone.Group 2: Fresh cortical cochlea wall covered with full thickness skin obtained from the external ear canal.Group 3: Fresh cochlea wall wrapped with carrageenan granuloma.Group 4: Fresh cochlea wall combined with full thickness canal skin and carrageenan granuloma.All the animals were sacrificed between 45 to 57 days after the implantation. After each specimen was removed, the size of the bone fragment was determined by the longest diameter with calipers under the operative microscope. Then, the specimen was fixed in formalin and used for histological study.In our stndy, the buried skin made a complete epidermal cyst subcutaneously in 70% of the 42 specimens. Microscopically, most of the bones implanted in various graft combinations indicated that the graft was the seat of a dual process, destruction and reconstruction. The inflammatory connective tissue, pyogenic or foreign body reaction produced by the skin cyst, was the common finding in bone resorption margins. The presence of the skin cyst with carrageenan was associated with the highest incidence of bone resorption in our series. On the other hand, the fact in our series that the skin cyst lied in a shallow or deep depression on the surface of a bone indicated that there might be a certain type of mechanical bone destruction in interaction of the skin cyst and bone. Therefore, it is suggested that the skin cyst adjacent to the bone or conective tissue may play an enhancing role in the localized bone destruction by:a. Promoting a persistent chronic inflammatory response in the underlying connective tissue, andb. Influencing bone cells by the physical presence as a space occupying structure.