Giant hepatic venous malformation
Giant hepatic venous malformations (also known as giant hepatic hemangiomas) are relatively uncommon non-neoplastic vascular lesions of the liver, which can be strikingly large and mimic tumors.
It is important to note that according to newer nomenclature, these lesions are merely known as slow flow venous malformations (ISSVA classification of vascular anomalies). Having said that, it is probably helpful in reports to include the word 'hemangioma' as this term is ubiquitous in the literature and more familiar to many clinicians. The remainder of this article uses the terms 'giant hepatic hemangioma' and 'giant hepatic venous malformation' interchangeably.
In addition, there is poor agreement in the literature as to the exact definition of what constitutes a "giant" hepatic hemangioma, as some of the literature defines as a size >4 cm but others >6 or even >10 cm. Either way, they are examples of atypical hepatic hemangiomas 3.
Many are asymptomatic, however hemorrhage, thrombosis, and mass effect may lead to abdominal fullness and pain. Depending on location and size mass effects on adjacent structures (biliary dilatation or vascular structures) may also lead to presentation.
Hemorrhage and/or rupture may also be encountered (typically following trauma or biopsy).
Giant hepatic venous malformations may contains areas of central necrosis/liquefaction, hemorrhage, peripheral calcification, fibrosis and thrombosis, resulting in heterogeneous appearance and incomplete opacification, even on very delayed imaging.
Giant hemangiomas may demonstrate similar findings to their smaller relatives, although findings are less consistent.
On noncontrast scans the lesions are usually heterogeneous hypoattenuating masses with marked central areas of low attenuation.
The typical enhancement pattern is peripheral nodular discontinuous enhancement that gradually fills centrally and follows aortic attenuation (same as for smaller hemangiomas).
Contrast filling may be slow and the central portions may never demonstrate complete contrast fill in. Occasionally, they may have minimal contrast enhancement.
Capsular retraction from scarring may also be seen.
- sharply marginated, hypointense mass
- cleft-like areas of low signal intensity
T1 C+ (Gd)
- cleft-like area may remain hypointense during enhancement
- enhancement pattern is otherwise similar to that seen on CT
- T2: cleft-like area may be markedly T2 hyperintense
Treatment and prognosis
Potential complications include: