Immunohistochemical study of carbonic anhydrase in mixed tumours from major salivary glands and skin.

Immunohistochemical distribution of carbonic anhydrase isoenzyme I and II was studied in mixed tumours of major salivary glands and skin. The normal salivary glands displayed strong carbonic anhydrase activity in both ductal epithelium and serous acinar cells and the serous demilune cells in the submandibular glands, including the eccrine ducts. Pleomorphic adenoma salivary gland origin exhibited positive staining in the inner-layer of epithelial cells of tubular, duct-like and glandular structures. No enzymatic staining was noted in the outer layer of tumour cells in these structures. Spindle tumour cells or the fibroblast-like cells with long cytoplasmic processes identified in the adjacent hyalin and myxomatous stroma were rarely positive, while chondroidal and osteo-chondroidal cells were highly reactive. Mixed tumours of eccrine gland origin showed the most reactive staining cells scattered throughout neoplastic epithelium in all tissues examined. Immunohistochemical stainability was usually higher for carbonic anhydrase II than I for both normal and tumour tissues. The biological roles of the distribution profiles of carbonic anhydrase are discussed.