Abstract
A 70-year-old man admitted to our hospital for abdominal pain was found, upon physical examination, to have a nonfixed tumor on the anterior rectal wall but no systemic lymph node swelling. No abnormalities were seen in laboratory findings. Barium enema showed an irregular filling defect in the ascending colon and a protruding tumor in the rectum. Colonoscopic examination showed a circumferential narrowing in the as-cending colon and a flatly elevated rectal tumor 2 cm in diameter. Biopsy from the rectal tumor showed well differentiated adenocarcinoma. Abdominal Computed Tomography showed no hepatolienal tumor or retroperitoneal lymph node swelling. Right hemicolectomy with lymph node dissection and anterior rectal resec-tion showed a 5×7.5 cm tumor in the ascending colon and a 2.7×1.8 cm tumor in the rectum. Histopathologic examination showed the colonic tumor to be a B-cell malignant lymphoma, consisting of diffuse medium-sized lymphoid cells. The rectal tumor was well differentiated adenocarcinoma. Two of the regional lymph nodes removed from the ascending colon were involved in the lymphoma. Primary colorectal malignant lymphoma is rare, and the coexistence of colorectal malignant lymphoma and adenocarcinoma has been reported in only 15 cases. In 7 of these, malignant lymphoma and adenocarcinoma were found at different sites of the large in-testine, ours is the eighth such case. Rectal malignant lymphoma thus appears to be found more frequently in tumor coexistence than in noncoexistence, but not to a statistically significant degree.
