Hemangioma is the most common benign tumor affecting the liver.
Hepatic hemangiomas are mesenchymal in origin and usually are solitary. Some authorities consider them to be benign congenital hamartomas. Hemangiomas are composed of masses of blood vessels that are atypical or irregular in arrangement and size.
The etiology of these lesions remains unknown, although oral contraceptives and steroids may accelerate the growth of a hemangioma. Whether or not these drugs actually induce the formation of the hemangioma is unclear.