Inside-out hemangioma

46-year-old female patient who came to our observation for research of abdominal vascular malformations with a family history of Rendu-Osler-Weber's disease. She did not have a history of previous illness or any medication.

An abdominal ultrasound scan revealed a 2.5-3 cm inhomogeneous mass located in S5 of the liver (figure 1). The mass presented as a complex cyst with anechoic and hyperechoic portions. Color Doppler doesn’t show any evident vascularity, but the mass seems to cause an extrinsic compression on a small hepatic venous vessel (figure 2). The evaluation with 2D SWE was inconclusive (figure 3). Contrast-enhanced US (CEUS) showed the presence of a central enhancing focus in the arterial phase (Figure 4a and 4b) followed by a centrifugal enhancement in the portal-venous (Figure 4c and 4d) and late phases (Figure 4e). The successive MIP evaluation confirmed the centrifugal enhancement from a central focus (figures 5a and b)

MRI confirmed the presence of the lesion in S5. The mass has high signal intensity on T2-weighted MR images (figure 6 a) and low signal intensity on T1-weighted MR images (Figure 6b). No difference in fat content at in-phase and out-phase evaluation (Figures 6c and d). After hepato-specific contrast injection, the lesion at dynamic MR images reveals a centrifugal enhancement pattern of the mass in arterial and portal phases (Figure 6e and f), without any peripheral not enhancing portion on 5-min delayed images (Figure 6g). The mass has low signal intensity (wash-out) on the biliary phase (figure 6h).

The aspects described are compatible with a centrifugal (inside-out) enhancement of an atypical liver hemangioma.

Centrifugal enhancement (inside-out) of hepatic hemangioma is a contrastographic behaviour characteristic of a relatively rare, atypical hepatic hemangioma, which precisely because of its imaging characteristics, often leads to concern that it may be a malignant lesion rather than benign (1-3). 

Epidemiology: Centrifugal (inside-out) enhancement of hepatic hemangiomas is a relatively rare feature. A prevalence by age and sex is not described in the literature (4).

Pathology: As a subtype of hepatic hemangioma, it is, as in all hemangiomas, characterized by the presence of dilated vascular channels lined with endothelial cells and fibrous stroma. Reports have suggested that an atypical central location of the vascular spaces, together with predominantly peripherally placed fibrous components, could be responsible for the centrifugal pattern of the enhancement (5).

Ultrasound: on ultrasound evaluation, most are hyperechoic, sometimes inhomogeneous, like other hemangiomas.

Contrast-enhanced ultrasound: at CEUS, these lesions show the presence of a centrifugal “inside-out” pattern of contrast media, defined as the presence of foci of central enhancement in the arterial phase followed by centrifugal enhancement in the subsequent portal-venous and late phases.

CE-MRI: the lesion it’s hypointense in T1-weighted and markedly hyperintense in T2-weighted images. At dynamic post-contrast evaluation, a gradual centrifugal enhancement it’s evident. The use of a hepatospecific contrast agent allows highlighting the absence of enhancement (wash-out) of the lesion in the biliary phase.

The marked hyperintensity of the lesion in T2-weighted images is one of the decisive and absolutely characteristic interpretative keys of the diagnosis of hemangioma. This is associated with the presence of intense enhancement in the arterial phase, similar to that of the vascular structures. The presence of late-phase enhancement on MRI would not exclude the diagnosis of cholangiocarcinoma, but the hyperechogenicity of the lesion in the late-phase CEUS rules out the diagnosis. The possibility of FNH, a diagnosis possible on evaluation at CEUS, is made less probable on MR evaluation due to the marked hyperintensity of the lesion in T2-weighted images and, impossible, due to the presence of wash-out in the biliary phase after hepatospecific contrast (6). The diagnosis of liver adenoma could be assumed only by the presence of wash-out in the biliary phase after hepatospecific contrast agent, but both the centrifugal behaviour after dynamic CE-MRI and CE-US (7) and, at the MRI, the characteristics of marked hyperintensity of the lesion on T2-weighted images, the absence of fat at the in-phase and out-phase images, rule out the diagnosis.