Clonal analysis of the epithelial component of W0arthin's tumor

The proliferation of the epithelial component of Warthin's tumor is generally considered to represent a neoplastic condition. There has been much controversy about the histogenesis of this tumor, and the clonality of the epithelial component has not been clarified. We examined the clonal status of epithelial cells of Warthin's tumor by using a polymerase chain reaction (PCR) method based on trinucleotide repeat polymorphism of the X chromosome-linked human androgen receptor gene (HUMARA) and on random inactivation of the gene by methylation. Total DNA was isolated from formalin-fixed, paraffin-embedded tissue from 16 women with Warthin's tumor. Of the 16 cases analyzed, 7 were heterozygous for the HUMARA polymorphism and informative. The epithelial components of the tumors from the 7 cases were microdissected under the light microscope, and were subjected to extraction of DNA and HUMARA analysis. Using a permanent aqueous mounting medium during microdissection, we succeeded in reducing the rate of contamination by lymphocytes in the samples to less than 10%. All 7 cases showed patterns of polyclonal proliferation in the HUMARA analysis. Our results showed the nonclonal nature of Warthin's tumor, suggesting that Warthin's tumor is a non-neoplastic tumor-like condition.