Stereologic analysis of the lymphoid stroma in parotid adenolymphoma

In 2 parotid adenolymphomas, the composition of lymphoid stroma was analysed, using stereologic point-counting methods at the electron microscopic level. In the 2 lesions, the stroma was almost identical with respect to organization and composition. Most areas of the stroma showed accumulation of mixed cell populations. On average, the latter were comprised of 5.1% fibroblastic/reticular cells, 2.7% macrophages, 68.9% small and 18.8% medium/large lymphocytes, 0.5% blastforming T-lymphocytes, 2.3% blastforming B-lymphocytes, and 1.6% plasma cells. Polymorphonuclear leukocytes and mast cells were extremely rare. Areas corresponding to the mantle zone of lymphoid follicles were found to contain 83.0% small and 15.8% medium/large lymphocytes. The present data seem to be in accordance with the speculation that the lymphoid stroma of adenolymphoma represents an immune reaction.