Inflammatory pseudotumor of the liver in patients with recurrent pyogenic cholangitis: CT-histopathologic correlation

PURPOSE: To correlate computed tomographic (CT) features of inflammatory ps eudotumors of the liver with histopathologic results in patients with recur rent pyogenic cholangitis. MATERIALS AND METHODS: CT features of 13 cases of inflammatory hepatic pseu dotumor in 10 patients with recurrent pyogenic cholangitis were reviewed. D iagnosis was made by means of surgical resection in all patients. CT scans were analyzed for the appearance of masses and ancillary findings in correl ation with the histopathologic findings in each resected specimen. RESULTS: The masses were 2.0-7.0 cm (mean, 3.5 cm). At nonenhanced CT, the masses appeared as ill-defined, hypoattenuating lesions. At-contrast materi al-enhanced CT, the masses exhibited central hypoattenuating areas with an iso- or hyperattenuating thickened periphery in four cases and a multisepta te appearance with hyperattenuating internal septa and periphery in nine ca ses. CT-histopathologic correlation showed that the central hypoattenuating area indicated the presence of chronic inflammatory infiltrates with foamy histiocytes, plasmacytes, and lymphocytes, while iso- or hyperattenuating areas in the periphery a nd internal septa of the mass represented fibrobla stic proliferation. All patients had CT features of recurrent pyogenic chol angitis, such as hepatolithiasis, intrahepatic duct stricture and dilatatio n, common bile duct calculi, pneumobilia, or parenchymal atrophy. CONCLUSION: Although CT features are not specific, inflammatory pseudotumor should be included in the differential diagnosis in patients with recurren t pyogenic cholangitis and a hepatic mass detected at CT.