Epithelioid angiomyolipoma of the liver: cross-sectional imaging findings of 10 immunohistochemically-verified cases.

AIM

To retrospectively evaluate the computed tomography (CT)/magnetic resonance imaging (MRI) imaging features of epithelioid angiomyolipoma of the liver (Epi-HAML), with pathology as a reference.

METHODS

The CT/MRI findings (number, diameter, lobar location, and appearance of lesions) in a series of 10 patients with 12 pathologically proven epithelioid angiomyolipomas of the liver were retrospectively analyzed. The imaging features, including attenuation/signal intensity characteristics, presence of fat, hypervascular, outer rim, and vessels within lesion, were evaluated and compared with that of non-Epi-HAML in 11 patients (13 lesions). The Fisher exact test was used to compare difference in probability of imaging features between the two types.

RESULTS

For 21 patients, CT images of 15 patients and MR images of six patients were available. No patient underwent two examinations. For the 15 patients with a CT scan, all HAML lesions in the two groups (10 Epi-HAML and seven non-Epi-HAML) manifested as hypoattenuation. For the six patients with MRI, all lesions (two Epi-HAML and six non-Epi-HAML) were hypointense on T1WI (fat suppression) and hyperintense on T2WI. There were 10 non-Epi-HAML, but only two Epi-HAML lesions showed the presence of fat, which significantly different between the two types (P = 0.005). On the dynamic contrast enhancement (DCE) imaging, eight Epi-HAML, and 13 non-Epi lesions manifested as hypervascular. Punctate or curved vessels were displayed in 10 Epi-HAML as well as in nine non-Epi lesions and outer rim enhancement could be found with eight Epi-HAML as well as six non-Epi lesions.

CONCLUSION

Little or no presence of adipose tissue was found to be an imaging feature of Epi-HAML, compared with the non-Epi type. In addition, hypervascularity with opacification of central punctiform or filiform vessels on DCE would be a characteristic enhancement pattern for Epi-HAML.