Inflammatory myofibroblastic tumors in the liver: MRI of two immunohistochemically-verified cases.

In immunohistochemically-proven hepatic inflammatory myofibroblastic tumors, MRI revealed layered patterns of contrast enhancement during dynamic imaging, consisting of outer hypovascular rind and inner hypervascular stroma and mimicking the imaging features of pyogenic organized abscess with deficient central necrosis in four lesions in two patients. For the outer hypovascular rind, T2-weighted images showed hyperintensity, suggesting immature fibrosis corresponding to the area of arterial hypovascularity and delayed contrast enhancement. The patients' favorable clinical course and imaging findings reflected the benign nature of these lesions, from an infectious origin, despite the phenotypic expression of myofibroblastic proliferation in the hypervascular stroma containing chronic inflammatory cells. (c) 2007 Wiley-Liss, Inc.