Hepatic angiosarcoma: cross-sectional imaging findings in seven patients with emphasis on dynamic contrast-enhanced and diffusion-weighted MRI

Primary hepatic angiosarcoma is a very rare and aggressive malignancy of vascular origin. We describe cross-sectional imaging findings of this entity with emphasis on dynamic contrast-enhanced (DCE) and diffusion-weighted (DWI) MR imaging. Seven cases of pathologically confirmed hepatic angiosarcoma were retrospectively reviewed (CT and MRI examinations were available in seven and six patients, respectively). Two radiologists evaluated lesion growth patterns, attenuation, signal intensity characteristics, contrast enhancement patterns, and apparent diffusion coefficients (ADCs). Multifocal hepatic disease was present in six patients by means of a mixed pattern of large dominant masses and multiple small nodules; one patient had a solitary large mass. Unenhanced images depicted hemorrhagic areas and a markedly heterogeneous internal architecture within large tumors. Contrast-enhanced early phase images showed variable patterns including patchy peripheral or bizarre shaped intralesional foci of enhancement, peripheral rim enhancement, and small lesions without enhancement. On DCE images, the majority of lesions presented with varying degrees of progressive enhancement. Small nodules frequently displayed homogeneous enhancement on delayed phase images due to complete fill-in. DWI revealed a high interlesional variability of ADC values (range 0.57-2.41 x 10(-3) mm(2)/s, mean 1.37 x 10(-3) mm(2)/s). Cross-sectional imaging findings of hepatic angiosarcoma reflect the varied histopathological composition of the tumors. Multifocal disease, hemorrhage within large lesions, as well as progressive enhancement on DCE images are typical features of hepatic angiosarcoma. The mean ADC of lesions was found to be slightly elevated in comparison with other hepatic malignancies.