Benign Liver Masses
Overview
Benign liver masses or lesions are relatively common in the liver. They may be detected on imaging studies incidentally or during investigation of abnormal liver function tests or abdominal pain. Differentiating benign liver lesions from cancers can sometimes be done by radiologic imaging studies alone. If the diagnosis is not clear, then often a liver biopsy is done to examine a sliver of the liver mass under the microscope. This allows the liver pathologist to determine the tissue diagnosis. It is helpful to compare the size of the lesion to prior imaging studies (if they exist), to determine if the mass is growing.
The main indication for resection of benign liver masses is for symptoms of abdominal pain or if the diagnosis is still in question after the evaluation. Follow-up imaging is important to ensure that the lesion is not enlarging.
Hemangioma
Hemangiomas (also referred to as hemangiomata) are the most common benign solid lesions that occur in the liver. They represent congenital vascular lesions that contain fibrous tissue and small blood vessels that eventually grow. They can range from small (1 centimeter or less) to giant cavernous hemangiomas (10 to 20 centimeters) in size. The most common symptom is pain, and often occurs in lesions greater than 5 to 6 centimeters in size. Spontaneous rupture (bleeding) is rare, and the main indication for resection is pain. Caution should be taken in ordering a liver biopsy if the suspected diagnosis is hemangioma, due to the risk of bleeding from the biopsy site, especially of the lesion is at the edge of the liver.
Adenoma
Hepatic adenomas are benign solid neoplasms of the liver. They are most commonly seen in young woman, and are typically solitary, although multiple adenomas also can occur. Prior or current use of estrogens (oral contraceptives) is a clear risk factor for development of a liver adenoma, although they can occur even in the absence of oral contraceptive use. Hepatic adenomas carry a significant risk of spontaneous rupture with intraperitoneal bleeding. Further, there is a risk of malignant transformation to a well-differentiated HCC. Therefore, it is usually recommended that a hepatic adenoma be surgically removed.
Focal Nodular Hyperplasia (FNH)
Focal nodular hyperplasia (FNH) is another solid, benign lesion of the liver. FNH lesions are usually well-circumscribed, with a typical “central scar” on CT imaging. Similar to adenomas, they are more common in women of childbearing age, although the link to oral contraceptive use is not as clear as with adenomas. Unlike adenomas, FNH lesions usually do not rupture spontaneously and carry no significant risk of malignant transformation. The main indication for surgical resection is abdominal pain.
Hepatic Cyst
Cysts of the liver are fluid-filled structures that can usually be differentiated from solid lesions by U/S or CT imaging. Differential diagnosis of hepatic cysts include simple liver cysts, biliary cysts, parasitic cysts, and cystadenomas. The treatment varies based on the nature of the cyst. When the cysts are large, they often produce abdominal pain or fullness and a palpable mass. Definitive treatment is surgical resection, although simple cysts can occasionally be managed by aspiration with or without sclerotherapy.