AgNOR counts in preneoplastic lesions of the bronchus

Silver staining of argyrophil nucleolar organizer regions (AgNORs) has become a valuable method to assess cell kinetics in paraffin sections and separate benign from malignant lesions. As a putative technique for the distinction between regenerative and preneoplastic alterations of the bronchial mucosa we employed the Ag-staining method, evaluating the number of dots/nucleus and shape of the dots. Dots/nucleus were counted by by standardized methods, and mean and standard deviation were calculated. Comparative investigations were performed in bioptically obtained specimens of normal bronchial epithelium (1.94 +/- 0.1 dots/nucleus, n = 12), basal cell hyperplasia (2.22 +/- 0.13 dots/nucleus, n = 15), goblet cell hyperplasia (2.38 +/- 0.16 dots/nucleus, n = 17), squamous cell metaplasia (2.58 +/- 0.17 dots/nucleus, n = 25), squamous cell metaplasia with mild and moderate dysplasia (2.50 +/- 0.5 dots/nucleus, n = 15), squamous cell metaplasia with severe dysplasia and carcinoma in situ (3.10 +/- 0.47 dots/nucleus, n = 17), micropapillomatosis (2.20 +/- 0.21 dots/nucleus, n = 13) and early squamous cell carcinoma of the bronchus (4.40 +/- 0.74, n = 13). In preneoplastic lesions a variability in form and size of the dots was found. Though showing an increase in the number of dots/nucleus coincidentally with the degree of proliferative activity, the AgNOR method cannot be considered as a statistically significant tool in the evaluation of regenerative and preneoplastic lesions in bioptically obtained specimens.