Abstract
The mechanism of bone resorption in middle ear cholesteatomas has been investigated over the past century. In the early and middle periods of the last century, bone resorption by cholesteatomas was explained by pressure exerted on the bone, which is currently rejected by most researchers. Since the 1980s, a diversity of cytokines, chemical mediators, and enzymes have been detected in cholesteatoma tissue, and presumed to be candidates that play pivotal roles in bone resorption in cholesteatomas. Among the candidates, interleukin-1α, tumor necrosis factor-α, and prostaglandin E2 have been most thoroughly investigated. In the 2000s, many researchers vigorously studied the regulation of osteoclasts by the RANKL/RANK/OPG system in connection with the above inflammatory products. However, the presence and participation of osteoclasts still remain unclear in human cholesteatoma lesions. Most recently, we reappraised bone resorption by acid lysis, which was first proposed in the 1950s. Hypotheses on the mechanism of bone resorption in middle ear cholesteatomas were comprehensively reviewed.
