Parenchymal changes of salivary glands adjacent to a variety of salivary gland disorders

A fully developed tumor is the first manifestation of a typical salivary gland neoplasm. Identification of precursor lesions and the accompanying clinical findings may improve our understanding of these tumors. The frequency of possible precursor lesions of salivary gland tumors have not been systematically investigated to date. In this study, slides of 661 cases from three pathology laboratories in Ankara, Turkey were reviewed to search for possible precursor lesions. Salivary gland parenchymal changes adjacent to a variety of salivary gland disorders such as metaplastic changes, ductal epithelial hyperplasia, adenomatoid ductal hyperplasia, adenomatoid oxyphilic hyperplasia, adenomatoid hyperplasia of the minor salivary glands, myoepithelial sialadenitis and dysplasia were screened histologically as potentially precursor lesions. Nuclear protein Ki-67 and cellular tumor antigen p53 were also analyzed immunohistochemically in selected cases. Approximately 16% of the cases in this series contained various types of pathologic hyperplasia. Only a minority of these lesions were originally reported, so most of the findings in this study were not part of the original histology reports. The majority of these parenchymal changes were seen in parotids. Adenomatoid ductal hyperplasia was the most frequent possible precursor lesion, and it was found most frequently around pleomorphic adenomas. Although the biological significance of most of the lesions described in this report still remains to be understood completely, efforts to define and detect possible preneoplastic lesions should be intensified. We believe that detection and eradication of the precursors is the best way of decreasing the overall morbidity caused by salivary gland tumors.