OBJECTIVETo investigate whether the cholesteatoma from different positions have different biological characteristics.

METHODSThe expression of the Ki-67 and collagen IV in 19 specimens of cholesteatoma were stained immunohistochemically using the SP method, according to the origin of the specimens, include 7 cases from the epitympanum, 8 cases from tympanic sinus and 4 cases from the out acoustic canal. According to the severity of the inflammation in the perimatrix, the inflammation group included 7 cases, the non-inflammation group included 8 cases.

RESULTSThe average count was the same between the cholesteatoma from epitympanum and tympanic sinus. And the count of the cholesteatoma in the middle ear was also the same to the cholesteatoma from the out acoustic canal. But even from the same sample, the cholesteatoma from the positions with severe inflammation in the perimatrix count much higher, and the difference was statistically significant. Collagen IV had been found to localized in the basic membrane. In some specimens the staining of the collagen IV was not continuous.

CONCLUSIONSThe results suggested that it was the severity of inflammation in the perimatrix influenced the differences, but not the origins of the cholesteatoma.