Hepatic cavernous haemangioma with AV hepato-portal shunts

Clinical History

The patient underwent a whole body CT for staging of rectal cancer.

Imaging Findings

Non-enhanced CT: the liver is diffusely hypoattenuating; a hyperattenuating subcapsular wedge-shaped area is visible in S7 (Fig. 1).

Multiphasic contrast-enhanced CT. Arterial phase: a 3-cm mass with globular peripheral enhancement is appreciable in S7 (Fig. 2a). The nodule is circumscribed by a triangular transient hepatic attenuation difference (THAD); small portal branches are also detectable (Fig. 2 a; Fig. 3 a, b). Late venous phase: the lesion is completely filled; enhancement of surrounding parenchyma is no longer visible (Fig. 2b).

Discussion

Multiphasic contrast-enhanced CT is a well-established technique playing a pivotal role in diagnostic imaging of liver pathology, since it improves detection and characterization of focal hepatic lesions, even of those small in size [1]; ability in demonstrating intrahepatic haemodynamic changes is an additional advantage [2, 3]. Moreover, dynamic CT is especially valuable in case of fatty infiltration of the liver, a frequent finding which can hide or change features of focal hepatic lesion [4, 5].

In case of steatosis cavernous haemangiomas present as nodules hyperattenuating relatively to the surrounding parenchyma on non-enhanced CT; anyway they preserve the typical peripheral globular enhancement with a progressive centripetal filling on dynamic imaging. Time for complete filling depends on size of vascular spaces and histology of haemangioma [1].

Hepatic haemangiomas can be associated to a hepatic-portal arterio-venous shunt (AVS), an asymptomatic condition which is likely more frequent as previously thought and not only typical of malignancies [6, 7]. Incidence of an AVS and size of hepatic haemangiomas are not statistically related; pathogenesis is not clearly understood but probably related to the presence of potential AV communications in high flow haemangiomas, as suggested by clinical and experimental investigations [8].

A hepatic AVS is easier to be demonstrated with arteriography than with multiphasic contrast-enhanced CT. Hepato-portal AVSs associated with focal hepatic lesion can be detectable on arterial phase CT by identification of early opacification of dependent portal branches [1]; enhancement of contralateral branch can occur in case of a larger shunt. Smaller shunts are indirectly identifiable only by the presence of a wedge-shaped THAD associated to a haemangioma; Hanafusa et al. found a THDA on arterial phase images in 24% of cases haemangiomas, 83% of which due to a hepato-portal AVS [9-10].
In patients with fatty liver infiltration THADs associated to focal hepatic lesions correspond to focal areas sparing from steatosis, because supplied by the systemic circulation it is poorer in nutrients and hormones than the blood supplied by the portal trunk [11].

In conclusion, arterio-portal AVS can be sometimes associated to a haemangioma of the liver. A typical pattern of multiphasic CT allows a confident diagnosis of a haemangioma and rules out a malignancy; characterization of a hepatic haemangiomas may be additionally improved by perfusion CT [12].

Differential Diagnosis List

Final Diagnosis

Cavernous haemangioma with hepato-portal AVS in hepatic steatosis

URL:	https://www.eurorad.org/case/12019
DOI:	10.1594/EURORAD/CASE.12019
ISSN:	1563-4086