PAPILLARY cystadenoma lymphomatosum is a relatively rare type of salivary gland tumor. It may be grouped roughly among the benign mixed tumors of the salivary glands but is so distinctive in its microscopic appearance that a special niche has been made for it. Because of the rarity of these tumors, one is inclined to dismiss them as pathological curiosities. However, when the surgeon is confronted with a patient with such a diagnosis, knowledge of the pathology, treatment, and prognosis are of paramount importance. We have had the opportunity to see two of these tumors within a period of four months, and these serve as the basis for this report. REPORT OF CASES Case 1 .—A 56 year old white man entered the hospital for evaluation of low back pain. An incidental finding was a firm, nontender tumor below the posterior part of the right mandible. The mass had been present