Pergamon Oral Oncol, EurJ Cancer, Vol. 32B, No. 3, pp. 154157, 1996 Copyright c 1996 Elsevier Science Ltd. All rights reserved Primed in Great Britain 096G1955196 $15.00+0.00 zyxwvuts 0964-1955(95)00090-9 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPO Papers Cell Kinetics of Pleomorphic Adenomas of the Parotid Gland L. Matturri,’ A.M. Lavezzi,’ B. Biondo’ and M. Mantovani2 ‘Institute of Pathology, University of Milan, Via della Commenda, 19-20122 Milan; and ‘Institute of Otorhinolaryngology, University of Milan, Italy The aim of the present study is to characterise the cell kinetics of pleomorphic adenoma of the parotid gland by assessing DNA content and proliferating cell nuclear antigen (PCNA) positivity. In 22 parotid adenomas, DNA content was measured by densitometry in histological serial sections stained with Feulgen’s method and PCNA positivity was determined by immunohistochemistry with the monoclonal antibody PClO. To assess the proliferative activity, DNA index and PCNA index were evaluated. It was possible to distinguish two types of adenoma. In Group I there was a prevalence of diploid cells with a low PCNA index. Group II is represented by adenomas with a large percentage of triploid cells and a PCNA index significantly higher than that of Group I. Our findings suggest that the possibility of recurrence or malignant transformation depends on intrinsic biological properties of each adenoma. Copyright 0 1996 Elsevier Science Ltd Keywords: cell kinetics, DNA content, PCNA index, pleomorphic adenoma, parotid gland zyxwvutsrqponmlkj Oral Oncol, Eur J Cancer, Vol. 32B, No. 3, pp. 154-157, 1996. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJI INTRODUCTION The pleomorphic adenoma is the most common tumour of the parotid gland. It is a benign lesion characterised by histomor- phologic heterogeneity, being made up of an epithelial component and a more or less abundant stroma which may be mucoid, myxoid or chondroid and is the product of the altered metabolism of the epithelial cells. On the basis of cell differentiation and amount and nature of the stroma, Seifert et al. [I] have proposed a subdivision of pleomorphic adenomas into four groups. However, irrespective of the histological aspect, local recurrence occurs in lo-12” ,, of parotid adenomas and malignant transformation is not uncommon [2, 31. Cytogenetic studies on this type of tumour have revealed different clonal chromosome anomalies and it has been hypothesised that these alterations may cause variations in proliferative activity [4-91. So far, however, the cell kinetics of pleomorphic adenoma of the parotid gland have been poorly investigated [ 10, 111. The aim of the present study, therefore, was to characterise the proliferative capacity of this tumour by assessing DNA content and labelling index with proliferating cell nuclear antigen (PCNA) of the epithelial component, and in particular to determine the percentage of cells in the S phase, which many studies have shown to be closely correlated to the biological Correspondence to L. Matturri. Received 10 Aug. 1995; provisionally accepted 20 Oct. 1995; revised manuscript received 23 Nov. 1995. behaviour and aggressiveness in various types of neoplasias [12-161. MATERIALS AND METHODS Twenty-two parotid adenomas, selected from 1989 to 1991, were investigated. In 19 of these, histological examination showed the tissue polymorphism typical of pleomorphic adenoma. The other 3 cases were diagnosed as “carcinoma in pleomorphic adenoma” (malignant mixed tumour), on the basis of histological observation showing the coexistence of carcinoma and a component having the typical appearance of pleomorphic adenoma [ 171. In all the adenomas (19 cases), and in the adenomatous areas adjacent to the carcinomas (3 cases), DNA content w as measured by densitometry and PCNA positivity was deter- mined by immunohistochemistry in serial sections. Since the aim of this study was to assess proliferative activity only in benign tumours, the carcinomas were not investigated. Immunohistochemical staining for PCNA Paraffin sections of 4-pm-thick from the same blocks used for histological diagnosis were air-dried overnight at room temperature and immunostained with the monoclonal anti- body PC10 at dilution of 1: 200, using an immunoperoxidase method (ABC complex) with light haematoxylin counterstain- ing. All immunostained sections were examined using a x 100 154