Hemangiomas of the liver are the most common benign masses and the second most common overall mass found in the liver.
Liver hemangiomas are blood-filled outpouches of the liver endothelium that become engorged and ectactic. It is assumed that they arise from enlargement of existing vascular sinusoids and not from growth of new blood vessels (i.e., angiogenesis).
Hemangiomas when enlarging appear to be surrounded by a capsule, which is more accurately characterized by compression of the normal surrounding liver parenchyma (tissue).
Blood flow in larger hemangiomas is abnormal and can be associated with internal hemorrhage, thrombosis, and fibrosis.
Hemangiomas are considerably more common in women than men and typically are discovered incidentally or present with symptoms between the ages of 40 and 60 years. The overall incidence in the general population is estimated to be 2% to 7%.
Development of liver hemangioma is associated with pregnancy and hormone replacement therapy, although a causal relationship has never been definitively established.
Hemangiomas can grow to be quite large and in some patients are noted to slowly enlarge. Lesions larger than 4-10 cm are often termed “giant”. Multiple hemangiomas occur in 30%-35% of patients.