Abnormal venous structures in salivary gland tumors: vasculature characteristics of pleomorphic adenoma

To clarify the diagnostic significance of abnormal venous structures presen t in salivary gland tumors, we examined 21 pleomorphic adenomas, 14 Warthin tumors, 1 oncocytic adenoma, 3 myoepitheliomas, 7 basal cell adenomas, 5 m ucoepidermoid carcinomas, and 6 adenoid cystic carcinomas. Verhoeff-van Gie son staining was carried out and the morphology of the veins within the tum ors was observed microscopically. Branching veins, thickened intima of the veins, discontinuous elastic membrane and multilayered elastic membrane wer e seen in 71.4%, 76.2%, 47.6% and 85.7% of pleomorphic adenomas, respective ly, and were abundant and easily found in most cases. The abnormal venous s tructures were also found in other salivary gland tumors examined, but they were few in number and lacked variety. Elastic fibers extending radially i nto the surrounding stroma were seen in 66.7% of pleomorphic adenomas, and were not seen in other salivary gland tumors. Our results showed that a var iety of abnormal venous structures are more abundant and more easily found in pleomorphic adenoma compared with other salivary gland tumors, and, in p articular, that perivascular radiating elastic fibers are characteristic of pleomorphic adenoma. We emphasize that the presence of perivascular radiat ing elastic fibers may be helpful in diagnosing pleomorphic adenoma in smal l biopsy specimens.