Colonic lymphoma and adenocarcinoma occurred together in a man with long-standing ulcerative colitis. The association between lymphoma and ulcerative colitis may be significant since primary colonic lymphomas are very rare. It is suggested that the factors which increase the risk of developing lymphoma of the colon in patients with ulcerative colitis may be the same as those which influence the development of adenocarcinoma, since most of the patients with either neoplasm were in their twenties at the time of onset of ulcerative colitis, the average duration of ulcerative colitis before developing lymphoma or carcinoma was long (12 years), and in most cases, the ulcerative colitis was severe and extensive. In both types of neoplastic disease, an abrupt change in symptoms is the most consistent indication that cancer has developed.Cancer 46:1695-1700, 1980.R I M A R Y LYMPHOMA of the colon and rectum is P very uncommon; Cornes ef ~1 .~ found only 4 cases of lymphosarcoma among 4,595 malignant tumors of the colon at St. Mark's Hospital, a large center for gastrointestinal diseases in London. While the most common neoplasm associated with ulcerative colitis is adenocarcinoma, the less frequent association with lymphoma has received little attention, probably because only 23 cases of primary colonic lymphoma associated with ulcerative colitis have been reThe coincidental occurrence of ulcerative colitis and lymphoma, rare as it is, has prompted speculation that a significant relationship may exist.2 In this report, we present a case of both histiocytic lymphoma and adenocarcinoma of the colon occurring in a man who had had ulcerative colitis for 18 years. ,-ted. Physical examination revealed no lymphadenopathy or hepatosplenomegaly. There was tenderness of the left abdomen with no palpable mass.Proctosigmoidoscopic examination showed multiple masses in the rectosigmoid colon and advanced ulcerative colitis. Results of barium-enema examination were interpreted as indicative of ulcerative colitis involving the entire colon and the terminal ileum. A well defined, irregular, fluoroscopically rigid-appearing, 9-cm segment constricted the mid-descending colon (Fig. 1). Chest x-ray, leukocyte count, and differential and other laboratory data including results of electrocardiogram, and hemoglobin, hematocrit, prothrombin time, and activated partial prothrombin time were interpreted as normal. Bone marrow morphology and differential count were within normal limits. On October 10, 1977, a total proctocolectomy was done. Intraoperatively , the liver, spleen, and periaortic and mesenteric lymph node areas were inspected and palpated and appeared, grossly, to be normal. The patient received multiple-agent chemotherapy (cytoxan, oncovin, procarbazine, and prednisone) and was alive and well 12 months after the colectomy. The operative specimen included the terminal ileum, colon, rectum, and anus. The mucosa of the ileum and colon was flat, finely granular and marked by numerous irregular ulcers. In the region of the descending col...