Warthin's tumor: an immunohistochemical study of its lymphoid stroma.

The lymphoid stroma of Warthin's tumor was studied using an immunoperoxidase method. We found that IgA plasma cells constituted approximately 80 per cent of the total number of plasma cells in this tumor. IgA was present also in the tumor epithelium and in the intraluminal sections. The predominance of IgA plasma cells in Warthin's tumor is in contrast to the lymphoid pattern observed in autoimmune diseases and usual host-tumor reactions. It seems likely that the lymphoid stroma of Warthin's tumor represents an exaggerated secretory immune response. The neoplastic tissue of Warthin's tumor may elaborate or contain an unknown factor that causes the accumulation of lymphoid tissue and the differentiation of IgA plasma cells.