Immunohistochemical characterization of cellular immunoglobulins and epithelial marker antigens in Warthin's tumor.

Lymphoid and epithelial cell marker studies based on paired immunofluorescence staining were performed on ethanol-fixed specimens from six Warthin's tumors of the parotid gland. A polyclonal pattern of isotype and light-chain expression was demonstrated for immunoglobulin-producing cells and afforded definitive evidence for the reactive nature of B-cell proliferation. The average percentages of IgG, IgA, IgM, IgD, and IgE immunocytes were 48.6, 38.5, 8.9, 3.3, and 0.7, respectively. The percentages of J-chain-positive cells within the first four isotypes were 11.3, 47.0, 67.2, and 64.4. Both features were more typical of immune responses in lymphoid tissues than in exocrine glands. In five of the six specimens, IgE was present in a prominent lacy pattern in some follicular centers, often extending to lymphocyte membranes of the mantle zone. Mast cells positive for IgE were seen in all cases. The two latter features indicate that type 1 hypersensitivity might contribute to the lesion. Parts of the tumor epithelium stained selectively for dimeric IgA and secretory component (SC), signifying secretory capacity. In addition, lactoferrin and carcinoembryonic antigen (CEA) occasionally were present in a narrow cytoplasmic luminal rim. Carcinoembryonic antigen was also seen in papillary epithelial projections. Lysozyme was found in isolated epithelial cells, whereas amylase was completely lacking. Except for the presence of CEA, this pattern of epithelial markers resembled that seen in striated ducts of normal salivary glands.