A mass on the liver refers to any abnormal growth, lump, or lesion found within the organ’s tissue. This discovery can cause immediate concern, but the term itself is non-specific and does not automatically indicate cancer. A liver mass is simply a descriptive finding seen on a medical scan, meaning it can range from a common, harmless growth to a serious malignancy. Understanding the nature of the mass is the immediate goal of subsequent medical evaluation.
How Liver Masses Are Discovered
Most liver masses are found entirely by chance during imaging tests performed for unrelated health issues. This phenomenon is known as an incidental finding, accounting for the majority of diagnoses in asymptomatic individuals. Common imaging modalities like abdominal ultrasound, Computed Tomography (CT), or Magnetic Resonance Imaging (MRI) often reveal these growths while screening for other conditions.
While many masses cause no symptoms, specific complaints may prompt investigation when the mass becomes large enough to press on surrounding structures. Patients may report a feeling of fullness, vague abdominal discomfort, or pain in the upper right quadrant. Unexplained weight loss or jaundice (yellowing of the skin and eyes) are less common but concerning symptoms that signal the need for comprehensive evaluation.
Classifying Liver Masses
The medical evaluation focuses on placing the mass into one of two categories: benign or malignant. Benign masses are non-cancerous and do not spread, while malignant masses are cancerous and can invade surrounding tissues. The vast majority of lesions discovered are benign, offering reassurance to most patients.
Malignant masses are further categorized based on their origin within the body. A mass that begins in the liver tissue itself is classified as a primary liver malignancy, such as Hepatocellular Carcinoma (HCC). Alternatively, a mass that has spread to the liver from a cancer that started in another organ, like the colon or lung, is termed a secondary or metastatic malignancy. Metastatic cancer is statistically the most common type of malignant tumor found in the liver, requiring a search for a primary source outside the liver as part of the diagnostic process.
Common Benign Growths
Benign masses are common and rarely pose a health risk, often requiring no treatment. The most frequent type is a Hepatic Hemangioma, a tangle of abnormal blood vessels. These are considered congenital and may be present in up to 20% of the population, often remaining small and asymptomatic. Hemangiomas are typically monitored with follow-up imaging but are only removed surgically if they grow large and cause pain or complications.
Another common non-cancerous lesion is Focal Nodular Hyperplasia (FNH), which is considered a tumor-like growth arising from a localized reaction to an abnormal artery. FNH is composed of normal liver cells, bile duct cells, and connective tissue, often featuring a characteristic “central scar” visible on imaging. It is more common in women and carries no risk of turning into cancer, so asymptomatic patients rarely require any intervention.
Liver Cysts are simple, fluid-filled sacs that are also a frequent incidental finding on imaging. Most simple cysts are harmless, do not grow, and require no follow-up. In the rare event a cyst becomes very large and causes abdominal discomfort or blocks a bile duct, a procedure to drain the fluid or surgically remove the cyst wall may be considered.
A less common but important benign mass is a Hepatocellular Adenoma (HCA), which originates from the main liver cells, called hepatocytes. These growths are typically associated with hormonal factors, such as the use of oral contraceptives or anabolic steroids. Adenomas are closely monitored because they carry a risk of rupturing and causing internal bleeding, particularly when larger than five centimeters. Specific subtypes, such as those with a beta-catenin mutation, also have an increased risk of malignant transformation, usually prompting a recommendation for surgical removal.
Malignant Mass Types and Management
When a liver mass is determined to be malignant, the type of cancer dictates the management plan. Hepatocellular Carcinoma (HCC) is the most prevalent form of cancer originating in the liver, strongly linked to chronic liver diseases such as cirrhosis from hepatitis B or C infection, or long-term alcohol abuse. HCC treatment is complex and depends on the tumor’s size, location, and the health of the remaining liver tissue.
Metastatic cancer, where cells have spread to the liver from a primary tumor elsewhere, is the most frequent malignant finding. Treatment for metastatic disease is determined by the source of the original cancer (e.g., colorectal or lung cancer) and typically involves systemic therapy like chemotherapy or immunotherapy.
Management for both primary and metastatic liver cancers involves a multidisciplinary approach. Surgical resection, which removes the tumor along with a margin of healthy tissue, offers the best chance of a cure for localized disease. For patients with small HCC tumors and underlying liver failure, a liver transplant may be the preferred curative option.
Non-surgical treatments include ablation therapies, such as radiofrequency ablation (RFA) or microwave ablation (MWA), which use heat to destroy the tumor cells. Embolization procedures cut off the tumor’s blood supply, sometimes delivering chemotherapy drugs or radiation beads directly to the mass. Newer systemic therapies, including targeted drugs and immunotherapy, work to help the patient’s own immune system fight the advanced cancer.