Benign lesions in the liver are sometimes caused by hormones, whether natural or synthetic, as in the case of hemangiomas and adenomas, according to California Pacific Medical Center. Lesions can also be caused by the distribution of fat in the liver and the presence of cysts.
Cysts found in the livers can be infectious or noninfectious, according to California Pacific Medical Center. Infectious cysts include liver abscesses, which are caused by bacteria or amoebas. Noninfectious cysts include polycystic liver disease, which is inherited.
Other lesions are caused by cancers of the liver, according to Cleveland Clinic. These cancers start in the liver and usually arise from cells called hepatocytes. Other types of malignant lesions found in the liver are the results of metastasis from other areas in the body.
Medical experts believe that hemangiomas are caused by hormonal fluctuations in the female body, according to California Pacific Medical Center. Interestingly, it is the smaller hemangiomas that cause symptoms. Usually, even large hemangiomas don't need treatment unless they are causing problems. Adenomas seem to be caused by oral contraceptives, and treatment may involve patients ceasing use of the contraceptives. Though these lesions are rare, the larger ones are at risk of bleeding and becoming malignant. This is why adenomas are best treated with surgery.