Spontaneous regression of inflammatory pseudotumor of the liver: report of three cases.

Inflammatory pseudotumor (IPT) of the liver is a rare benign hepatic lesion that sometimes mimics malignant tumors. An accurate diagnosis of IPT is important to avoid unnecessary surgery. We herein report three cases of IPT of the liver that spontaneously regressed and were successfully diagnosed without a surgical resection. Malignant tumors were initially suspected based on the initial imaging findings, including ultrasonography, computed tomography (CT), and magnetic resonance imaging. In particular, a delayed enhancement in the periphery of the masses was observed on dynamic CT scans, similar to the imaging results for metastatic tumors or intrahepatic cholangiocarcinomas. The serum levels of C-reactive protein were elevated in all three patients (6.6, 3.4, and 1.5 mg/dl), while the serum levels of tumor markers were almost within the normal ranges (carcinoembryonic antigen, <5 ng/ml; carbohydrate antigen 19-9, 201, 3, and 14 U/ml). Serial repeated imaging studies over the course of a month showed the spontaneous regression of the hepatic tumors, thus enabling us to make a diagnosis of IPT without a surgical resection. A percutaneous biopsy confirmed the histology in one case. The regression of tumors on repeated images should play a key role in making an accurate diagnosis of IPT.