An inflammatory pseudotumor of the liver was discovered during a metastatic examination of a patient with rectal adenocarcinoma. Magnetic resonance imaging showed a three-component lesion that infiltrated a large portal vein, and CT arteriography and CT during arterial portography showed a portal obstruction. A histopathological examination proved that necrosis was present in the central zone; infiltration by proliferating connective tissue with chronic inflammatory cells was prominent in the middle zone; and fibrous changes, including pseudo-bile duct proliferation, were present in the peripheral zone. Magnetic resonance imaging revealed both portal infiltration and histopathological features including the above-noted three components. Magnetic resonance imaging is perhaps the most useful diagnostic modality.