RADIOLOGY: ABDOMEN: Case# 32876: NON-HODGKINS LYMPHOMA, SPLENIC INVOLVEMENT(EXAM1), WITH SIGMOID COLON MASS AND COLO-VESICLE FISTULA. Exam 1: Patient is a 72 year old male with recent diagnosis of lymphoma. CT is requested to further evaluate. Exam 2: Follow-up evaluation of a colovesical fistula in a patient with non-Hodgkins lymphoma. Exam 1: The spleen is markedly enlarged measuring 21 cm in craniocaudad dimension. Focal areas of low attenuation are noted. A 11 x 10 cm gas containing necrotic mass which appears to arise from a loop of sigmoid colon in the low pelvis. The adjacent sigmoid colon demonstrates significant wall thickening. The remainder of the colon appears unremarkable. Exam 2: Within the abdomen, ascites has developed, when compared with the previous study, and can be seen extending around the liver and spleen and into the lesser sac. Retrocrural and para-aortic lymphadenopathy is unchanged from the previous examination. Within the pelvis, the markedly thickened wall and haustral folds of the sigmoid colon are again demonstrated. Incorporated into this huge sigmoid colon mass is a cavity which is now smaller in size. Contained within the cavity is an air fluid level. The contrast within this has the same density as the contrast within the urinary bladder. Free gas is seen within the bladder. A fistulous tract is not directly visualized but assumed to be present. Free fluid is seen within the pelvis adjacent to the bladder and sigmoid colon. Lymphomas are malignant neoplasms which can be classified as either Hodgkins disease or non-Hodgkins lymphoma based on the presence of the Reed-Sternberg giant cell which is the key morphological finding in Hodgkins disease. Non- Hodgkins lymphoma (NHL) usually presents as a localized or generalized adenopathy, although in one third of cases the disease may be primary in other sites where lymphoid tissue is located such as the oropharyngeal region, gut, bone marrow, and skin. All lymphomas have the potential to metastasize to other lymph nodes and eventually to infiltrate the spleen, bone marrow, and liver. If the disease spreads to the blood the patients peripheral blood will resemble that of a leukemic patient. CT findings of NHL include multiple enlarged individual nodes and coalescence of enlarged nodes to form rounded multilobular masses which may encase vessels, displace organs, and obstruct ureters. Conglomerate nodal masses are typical of lymphoma and are rarely seen in other diseases. CT findings of primary and secondary lymphoma of the liver include low attenuation masses which are often large and well circumscribed. Diffuse infiltration may or may not cause hepatomegaly and thus may be difficult to distinguish from normal liver tissue.