Primary colorectal lymphoma: spectrum of imaging findings with pathologic correlation.

Primary colorectal lymphoma is a very uncommon disease; therefore, it has received little attention in the radiology literature. Moreover, imaging features of newly described pathologic subtypes have not been reported such as low-grade B-cell lymphoma arising from mucosa-associated lymphoid tissue and peripheral T-cell lymphoma that involves colorectal area. We retrospectively reviewed double-contrast barium enema and CT scans in the patients with primary colorectal lymphoma. In this article the radiologic appearances of primary colorectal lymphoma are categorized into focal lesion and diffuse lesion. Focal lesion includes polypoid mass, circumferential infiltration with smooth mucosal surface, circumferential infiltration with extensive ulceration, cavitary mass, mucosal nodularity, and mucosal fold thickening. Diffuse lesion includes diffuse ulcerative lesion and diffuse nodular lesion. Peripheral T-cell lymphomas that involve the colon manifested as either a diffuse or focal segmental lesion and showed extensive mucosal ulceration. These findings are similar to those of Crohn's disease or tuberculous colitis and are different from those of previously reported colorectal lymphoma. Low-grade B-cell lymphoma arising from mucosa-associated lymphoid tissue manifest as multiple mucosal nodularity. The imaging features of primary colorectal lymphoma are quite variable and overlap with other colonic pathology; however, it is important for radiologists to know the imaging features of primary colorectal lymphoma with their pathologic correlation.