Lymphangioma usually occurs in children and usually involves the skin. Mesenteric lymphangioma is extremely rare in adults. Typically, lymphangioma appears on computed tomography (CT) as a lower attenuation of a cystic mass, however, some cases appear to be a solid mass. We describe the CT and 18FFDG positron emission tomography/CT appearance in a case of jejunal and mesenteric cavous lymphangiomatosis mimicking metastasis in an adult patient with rectal cancer.