Benign liver lesions are non-cancerous growths that develop in the liver. These growths are quite common and are often discovered incidentally during imaging tests performed for other health concerns. They do not spread to other parts of the body, distinguishing them from malignant, or cancerous, liver tumors.
Understanding Benign Liver Lesions
The liver can develop several types of benign lesions, each with distinct characteristics. Hemangiomas, the most common type, consist of abnormal blood vessels, found in up to 20% of adults, and are typically asymptomatic, rarely requiring treatment. Focal nodular hyperplasia (FNH), the second most common type, arises from abnormal cells, often featuring a central scar, and is generally discovered by chance, primarily affecting women aged 20-50. Hepatocellular adenomas are less common but are notable for their potential association with hormone use.
Do They Grow?
Many benign liver lesions remain stable in size over extended periods, often causing no symptoms. For instance, most liver hemangiomas do not grow and do not lead to cancer. Similarly, focal nodular hyperplasia lesions are generally stable and rarely increase significantly in size. However, some benign liver lesions can indeed grow, though this varies by type and individual factors.
Hepatocellular adenomas, for example, can range significantly in size, from less than a centimeter to potentially 30 centimeters. These lesions have a small but significant risk of progressing into malignancy, unlike hemangiomas or FNH. While many hemangiomas stay small, larger ones can sometimes increase in size, especially in response to hormonal changes. Although FNH lesions usually remain unchanged, some have been observed to enlarge, particularly in certain circumstances.
Factors Influencing Growth
Several factors can influence whether a benign liver lesion grows. Hormonal influences play a role, particularly for hepatocellular adenomas. The use of oral contraceptive pills and pregnancy are linked to the growth of these adenomas due to increased estrogen levels. Some studies suggest that anabolic steroids can also contribute to adenoma development. These hormonal connections highlight a mechanism behind the enlargement of certain lesions.
For focal nodular hyperplasia, while typically stable, some cases show growth, especially in women who are pregnant or using birth control pills. This suggests a similar hormonal sensitivity for FNH, though its growth is less common and less concerning than for adenomas. Hemangiomas, while largely stable, can also occasionally grow, and estrogen is believed to contribute to this increase in size or number. Underlying liver conditions or specific genetic factors may also influence lesion behavior.
Monitoring and Clinical Implications
Healthcare professionals typically monitor benign liver lesions, especially those with growth potential, through regular imaging studies. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans are common tools used to track changes in a lesion’s size and characteristics over time. These imaging techniques help differentiate benign lesions from malignant ones and assess any growth.
Growth becomes a concern if it leads to symptoms such as abdominal pain or a feeling of fullness, or if the lesion reaches a very large size. For hepatocellular adenomas, growth also raises concerns about potential rupture or, in rare instances, malignant transformation. Most benign lesions, even if they exhibit some growth, do not require active treatment beyond continued observation. Surgical intervention is considered in rare cases, if the lesion causes significant symptoms, reaches a concerning size, or shows signs of higher risk.