The specific distribution of dendritic interstitial cells at the tumor border of major salivary gland pleomorphic adenomas.

To investigate the role of stromal cells at the tumor border of major salivary gland pleomorphic adenomas, we performed immunohistochemical analysis for detecting CD34-positive stromal cells (dendritic interstitial cells) and alpha smooth muscle actin (ASMA) -positive stromal cells (myofibroblasts) at the periphery of the tumor. We examined 21 pleomorphic adenomas of major salivary glands. All of the 21 pleomorphic adenomas examined had both dendritic interstitial cells and myofibroblasts at the tumor border. The ratio between the two cell types varied, and they exhibited a bilayered capsular structure; myofibroblasts were located in the inner layer of the tumor capsule, whereas dendritic interstitial cells derived from nearby vascular structures and nerves were located in the outer layer of the capsule. On the basis of the specific distribution of the dendritic interstitial cells in the present study, there is a possibility that dendritic interstitial cells are associated with the tumor growth regulation of major salivary gland pleomorphic adenomas.