1997 Volume 7 Issue 5 Pages 567-573
The pathogenesis of middle ear cholesteatoma is considered as the migrating process of keratinizing epithelia with hyperproliferative behavior to the middle ear cavity. In the present study, antibodies to the proliferating cell nuclear antigen (PCNA), which is a marker for proliferating cells in the S phase cell cycle, and specific cytokeratins (CKs) 5 and 19 were used in order to characterize cellular growth in middle ear cholesteatoma. Confocal laser scanning microscopy (CLSM) was employed to assess the density of antigen positive cells and to evaluate the fluorescence intensity quantitatively. PCNA positive cells were consistently identified in the basal and suprabasal matrix layers of cholesteatoma. Well-developed thick epithelia generally showed an intense PCNA staining compared to that of thin and flattened matrix tissues. The average cell densities positively stained for PCNA were 780.3cells/mm2 in 79 cholesteatoma specimens taken from 25 patients, and 257.8cells/mm2 in 8 control specimens of external meatal skin. The degree of cytokeratin expression as determined by fluorescent intensity of the labeled cells was correlated with the PCNA distribution in each sample. The presence of CK5 was broadly confirmed in cholesteatoma matrix. In contrast, a focal expression of CK19, which is known to reflect the presence of proliferating stem cells, was found in the basal layer of well-developed cholesteatoma matrix. A positive correlation was found between the degree of CK19 reactivity and the density of PCNA distribution (R=0.72, Pearson). Our results indicate that unusual growth patterns of cholesteatoma are mainly ascribable to the hyperproliferative activity of the basal and suprabasal layers, and their activities may vary considerably in each specimen.
