Immunohistochemical Demonstration of Type II Collagen in the Chondroid Tissue of Pleomorphic Adenomas of the Salivary Glands

A study was done to investigate the presence of type II collagen and elastin in the metaplastic chondroid tissue of 21 pleornorphic adenomas of the major and minor salivary glands. Type II collagen was detected with anti-bovine type II collagen antibody after double digestion of histological sections with trypsin and hyaluronidase. The immunoreaction was positive in the chondrocytic cells and intercellular matrix. Elastic fibers in the chondroid tissue were found by orcein staining; they were scarce and randomly distributed. Although the presence of type II collagen and elastin in the metaplastic chondroid tissue is not directly implicated in the genesis of the tumor, it reveals a unique and high grade of cellular differentiation in comparison with true cartilage.