Abstract
The aggressive resorption process of the temporal bone structure adjacent to the matrix is one of the most distinct clinical findings of middle ear cholesteatoma. Recently, the receptor activator of NF κ-B ligand (RANKL), a part of the combination of the ligand-receptor system, is known to be deeply involved in the maturation and activation of osteoclasts. In this study, we have semi-quantitatively assessed the degree of immunohistological expression of RANKL and Ki-67, a proliferation marker, in 26 chlesteatoma patients. Positive expression of RANKL was predominantly detected mainly in basal and para-basal layers of the matrix accompanying with severe inflammatory cell infiltration in the submucosal layer. The Ki-67 labeling index (LI) was 27.7 in the group with higher RANKL expression and 15.7 in the group with lower RANKL expression, and the difference was statistically significant. These results suggest that epithelial proliferative activities and inflammatory manifestation could be the possible factors responsible for the markedly increased bone resorption observed in cholesteatoma patients.
