Immunohistology of adenolymphoma (Warthin's tumour): evidence for a role of vascularization in the organization of the lympho-epithelial structure.

The epithelial, vascular and lymphoid components present in two cases of adenolymphoma (Warthin's tumour) were characterized by immunohistochemistry on frozen sections. Epithelial cells were positive for cytokeratin and keratin and were in close contact with numerous factor VIII related antigen-positive capillary vessels, running parallel to the epithelial basement membrane. The capillary vessels were in communication with high endothelial post-capillary venules which were often lined by HLA-DR-positive endothelial cells. The lymphoid tissue was organized in B-cell and T-cell areas. The B-cell areas consisted of B4+/To15+ B-lymphocytes admixed with DRC-1-positive follicular dendritic reticulum cells. The T-cell areas were mainly populated by T11+/T3+/T4+ lymphocytes admixed with some S-100+/HLA-DR+ interdigitating reticulum cells. Plasma cells and T8+ lymphocytes were more numerous in the proximity of the epithelium. Leu-M3+/PAM-1+ macrophages were scattered singly in the T-cell areas or were arranged in sinus-like structures around the epithelial cysts. The epithelial basement membrane, the vascular membrane and the fibrillar reticular stroma of the lymphoid tissue were immunoreactive for laminin and type IV collagen. The possibility is discussed that the accumulation of lymphoid tissue in Warthin's tumour is modulated by the epithelial cells, perhaps through their ability to organize a peculiar pattern of vascularization.