A liver lesion is a general term for an abnormal growth or cluster of cells within the liver, often discovered incidentally during imaging tests for unrelated medical issues. These growths, also called masses or tumors, can be benign (non-cancerous) and may not pose a health risk. However, some can be malignant (cancerous), which requires further medical evaluation and management.
Types of Liver Lesions
Liver lesions are first classified as either benign or malignant. Benign lesions are non-cancerous, grow slowly, and do not spread. Malignant lesions are cancerous and have the potential to invade surrounding tissues and spread to distant organs.
Among the most common benign lesions is the hemangioma, which is an abnormal mass of blood vessels. Another frequent type is the simple liver cyst, a sac filled with fluid. Focal nodular hyperplasia (FNH) is the second most common benign lesion and is thought to result from changes in liver cells due to variations in blood flow. Hepatic adenomas are less common benign tumors sometimes associated with the use of oral contraceptives.
Malignant lesions are either primary or secondary. Primary liver cancer originates within the liver tissue, with hepatocellular carcinoma being the most prevalent form, often developing in livers damaged by long-term conditions. Secondary, or metastatic, liver lesions occur when cancer from another part of the body, such as the colon or lung, spreads to the liver.
Common Causes and Risk Factors
For many benign lesions, the exact cause is not always clear, and they are often thought to be congenital or develop without a specific trigger. Some have known associations; for example, hepatic adenomas have a recognized link to oral contraceptive use, particularly older, high-estrogen formulations.
The risk factors for malignant liver lesions relate to chronic liver inflammation and damage. Cirrhosis, a condition where scar tissue replaces healthy liver cells, is a significant precursor, with most individuals diagnosed with hepatocellular carcinoma having underlying cirrhosis. This scarring can be caused by chronic viral infections like hepatitis B and hepatitis C.
Prolonged and excessive alcohol consumption is another cause of cirrhosis and a major risk factor for liver cancer. Non-alcoholic fatty liver disease (NAFLD) has emerged as a growing concern. NAFLD is the buildup of excess fat in liver cells not caused by alcohol and is linked to obesity and metabolic syndrome. Other risk factors include certain genetic conditions like hemochromatosis and exposure to environmental toxins like aflatoxin.
Diagnosis and Monitoring
The diagnosis of a liver lesion begins when an abnormality is detected on an imaging study. Initial tests often include an ultrasound, which uses sound waves to create images of the liver and can help differentiate between a solid mass and a fluid-filled cyst. To gain more detailed information, physicians use advanced imaging like a computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan.
Blood tests are also used to assess liver function and check for specific tumor markers, which are substances that can be elevated in the presence of cancer. While these markers can be suggestive, they are not definitive on their own. If imaging and blood tests are inconclusive, a liver biopsy may be performed, where a small tissue sample is removed with a needle and examined under a microscope for a definitive diagnosis.
For many small, benign lesions that are not causing symptoms, the recommended course of action is active surveillance. This involves periodic follow-up imaging tests, such as an ultrasound or MRI, to ensure the lesion is not growing or changing. The frequency of these scans depends on the type and size of the lesion.
Medical Management and Treatment Approaches
The management strategy for a liver lesion is determined by its type, size, symptoms, and whether it is benign or malignant. For most benign lesions that cause no symptoms, such as small hemangiomas and simple cysts, no treatment is necessary beyond the periodic monitoring discussed previously. If a benign lesion grows large enough to cause pain or other symptoms, surgery to remove it may be an option.
When a lesion is malignant, the treatment plan is tailored to the cancer’s type, stage, and the patient’s overall health.
- Surgical resection, the removal of the cancerous part of the liver, offers a potential cure if the cancer is caught early.
- Ablation therapies use heat or cold to destroy cancer cells directly for patients who are not candidates for resection.
- Embolization procedures block the blood supply to the tumor, starving it of nutrients.
- Radiation therapy can be delivered from outside the body or internally through radioactive beads placed near the tumor.
- A liver transplant may be the most suitable option in cases of extensive primary liver cancer or severe underlying cirrhosis.
- Systemic treatments like chemotherapy, targeted therapy, or immunotherapy are used for cancers that have spread or cannot be treated with localized methods.