ABSTRACT
BACKGROUND AND OBJECTIVES: The Nucleolar organizer regions (NORs) are one of markers of cellular proliferation. Because the NORs can be visualized by a silver staining technique, the NORs are called the argyrophilic nucleolar organizer regions (AgNORs). The expression patterns of proliferative markers have been reported in the cholesteatoma, but the AgNORs have not been studied in the cholesteatoma. We investigated the proliferative activities of the cholesteatoma by the AgNORs and the usefulness of the AgNORs as a proliferative index in the cholesteatoma. MATERIALS AND METHODS: We assessed 5 postauricular skin samples and 20 cholesteatoma specimens by the numbers of the total AgNORs and the large AgNORs (large AgNOR means a diameter of over 6 nm) in high power fields and each cell. And the total areas of the AgNORs in high power fields (HPF) were calculated. RESULTS: The numbers of the large AgNORs in HPF, the numbers of AgNORs in each cell and the total areas of the AgNORs in HPF of the cholesteatoma were higher than those of the controls (p<0.05). In the cholesteatoma, the numbers of the large AgNORs and the total areas of the AgNORs in HPF were the highest in the keratinizing squamous epithelium of thick portion followed by the non-keratinizing squamous epithelium, and the keratinizing epithelium of thin portion. The numbers of the large AgNORs in each cell of the basal and superficial layers were the highest in the thick keratinizing squamous epithelium. In the suprabasal layer, the non-keratinizing squamous epithelium showed higher numbers of the large AgNORs but showed no statistical significance. CONCLUSION: 1) The proliferative capacity of the epithelium of cholesteatoma is reactive proliferative status. 2) The proliferative activity is varied with the differentiation status of the squamous epithelium in the cholesteatoma.