Immunohistochemical studies on the epithelial and lymphoid components of Warthin's tumour.

The lymphoid and epithelial elements of three Warthin's tumours (adenolymphomas) were studied by immunohistochemical technique. All classes of immunoglobulin (Ig)-producing cells were found, except IgE immunocytes. The numbers of cells/mm2 section area (median and range) were: 20.4 (15.2--27.2), 4.8 (2.8--12.4). 4.8 (0.4--9.6) and O (0--1.2) for IgG-, IgA-, IgM- and IgD-producing cells respectively. This gives percentage class ratios (68:16:16:0) which are quite different from those found in normal parotid tissue (3.6:91:3.1:2.6). Thus, the immunocytes found in Warthin's tumour are clearly polyclonal and show a class distribution comparable to that of lymphoid organs such as the tonsils. Also as in such organs, there were lymphoid follicles with mantle zone of B lymphocytes bearing membrane-bound IgM and IgD, and germinal centres showing reticular IgM staining. Apical staining for IgA and secretory component (SC) was shown in the luminal cells of the tumour epithelium, giving a fluorescence pattern similar to that of normal striated ducts. Selective transport of IgA apparently taken place into the cystic spaces of the tumour. Carcino-embryonic antigen (CEA), normally absent from striated ducts, was not generally present in the tumour epithelium, but was found in small groups of cells, especially in papilliferous parts of the epithelium. Warthin's tumour therefore seems to be composed of a fairly inactive normal lymphoreticular tissue and a neoplastic duct epithelium, most of which is highly differentiated with retention of immunoglobulin transport.