Immunohistopathology of papillary cystadenoma lymphomatosum (Warthin's tumor)

A retrospective study of various benign salivary gland neoplasms was designed to study the frequency distribution and density of immunoglobulins (Igs) located within their various tissue compartments. Buffered-formalin fixed, paraffin embedded sections of Warthin's tumor, cystadenoma, oncocytoma, autoimmune thyroiditis, normal salivary gland, and reactive peripheral lymph node were obtained and processed via the peroxidase-antiperoxidase method following trypsinization to re-expose antigenic sites. The subepithelial and parafollicular zones of Warthin's tumor show an Ig density distribution (IgA greater than or equal to IgG) much greater than IgM, but the relative densities in the germinal center are (IgG = IgM) much greater than IgA. In contrast, the normal salivary gland displays almost exclusively IgA positive cells with only an occasional IgG or IgM positive cell. In general, the three salivary gland neoplasms considered all display a relatively similar frequency distribution with (IgA greater than or equal to IgG) much greater than IgM and much greater densities of all Igs than encountered in the normal salivary gland; however, the densities of IgA and IgG positive cells are greatest in Warthin's tumor. A similar frequency distribution of immunocytes in the parafollicular zone of autoimmune thyroiditis and Warthin's tumor is noted with an increased density of all Igs occurring in autoimmune thyroiditis. A significant increase in the density of IgA immunocytes is noted in the germinal centers of autoimmune thyroiditis. A comparison of Warthin's tumor with a reactive peripheral lymph node shows a marked increase in the density and frequency of IgA in the parafollicular zone in the former lesion, and significant elevations of IgG and IgM in the latter process both in the parafollicular zone and in the germinal centers. No data generated by this study support an autoimmune etiology of Warthin's tumor. Histopathologically, the oncocytoma appears to represent a pathologic entity distinctly different from papillary cystadenoma lymphomatosum. Our data tend to support the hypothesis that Warthin's tumor arises within ectopic salivary gland elements trapped within paraparotid or intraparotid lymph nodes during embryogenesis. The cystadenoma appears to represent a similar pathologic process arising in salivary gland elements independent of lymphoid tissue.