The liver is a large organ located in the upper right part of the abdomen, performing functions including filtering blood, metabolizing nutrients, and producing bile. A lesion on the liver is a term used by medical professionals to describe an area of abnormal tissue or a mass found within the organ. This finding is often made incidentally during imaging tests. Understanding the nature of the abnormal tissue guides any necessary next steps.
Understanding What a Lesion Is
A liver lesion is a general description for any growth, cyst, or tumor that appears different from the surrounding healthy liver tissue. Lesions are categorized as either benign (non-cancerous) or malignant (cancerous). Most lesions are benign and do not spread, while malignant lesions require intervention.
The appearance of a lesion on an initial scan, such as an ultrasound or CT, is rarely definitive proof of its nature. Imaging characteristics like size, shape, and internal composition help doctors narrow the possibilities. Further testing is required to determine the lesion’s nature, as the distinction between benign and malignant dictates the management plan.
Common Non-Cancerous Liver Lesions
The majority of lesions found in the liver are benign and do not require treatment. One common type is a hepatic hemangioma, an abnormal mass of blood vessels. Hemangiomas are present in up to five percent of the adult population and rarely cause symptoms or complications.
Another common finding is a simple liver cyst, a thin-walled sac filled with fluid. These cysts are typically asymptomatic and are often present from birth. They are generally left alone unless they grow large enough to cause pain or pressure.
Focal nodular hyperplasia (FNH) is a non-cancerous growth sometimes mistaken for a tumor. FNH is a mass composed of normal liver cells and connective tissue, often characterized by a central scar on imaging. This lesion is more common in women and carries no risk of turning into cancer. Once properly identified, these benign lesions often require only periodic monitoring.
Malignant Lesions and Their Sources
Malignant liver lesions are cancerous and can arise from the liver itself (primary cancer) or spread from another part of the body (metastatic cancer). Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer. HCC is strongly associated with chronic liver damage and scarring, known as cirrhosis, often caused by long-term hepatitis B or C infection.
In the United States and Europe, the most frequent type of cancerous lesion is metastatic cancer. Metastatic lesions occur when cancer cells from an original tumor elsewhere, such as the colon, lung, or breast, travel through the bloodstream and colonize the liver. These lesions are named for the original site of the cancer.
Risk factors for primary liver cancer include chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV). HBV can cause cancer even without cirrhosis, while HCV typically leads to HCC after years of chronic infection. Other factors include heavy alcohol use, inherited diseases, and metabolic dysfunction-associated steatotic liver disease.
Diagnosis and Management Pathways
Characterizing a liver lesion begins with imaging, often starting with an ultrasound due to its accessibility. If the lesion is not clearly identifiable, a physician orders more sophisticated imaging, such as a CT scan or an MRI. MRI is often the preferred method for evaluation because of its superior soft tissue contrast and use of specialized contrast agents.
Advanced scans use contrast enhancement to analyze how the lesion takes up and washes out the dye, providing clues about its cellular composition. A characteristic pattern on an MRI can provide a confident diagnosis of a hemangioma or FNH, often avoiding further invasive procedures. If imaging results remain inconclusive or suggest malignancy, a biopsy may be performed.
A biopsy involves using a fine needle to extract a small tissue sample, which is examined under a microscope to confirm the exact cell type. Management depends entirely on the diagnosis. Small, benign lesions are usually managed with watchful waiting. Malignant lesions may require surgical removal, localized destruction (ablation), or systemic treatments like chemotherapy or immunotherapy.