A benign liver tumor is a non-cancerous growth of cells in the liver. These growths are common and are distinct from malignant tumors because they do not spread to other parts of the body, meaning they are not life-threatening. In most cases, they do not cause symptoms or affect the liver’s ability to function. They are often discovered by chance during medical imaging for unrelated health issues.
Common Types of Benign Liver Tumors
The most frequently identified type of benign liver tumor is the hepatic hemangioma. This formation is a tangle of abnormal blood vessels and is the most common benign solid lesion of the liver. Hemangiomas are found in up to 5% of adults, with a higher prevalence in women, and are typically diagnosed between the ages of 30 and 50. Their size can range from very small to quite large, though most remain small and asymptomatic.
Another common type is focal nodular hyperplasia (FNH), the second most prevalent benign liver tumor after hemangiomas. FNH is a tumor-like growth composed of several cell types that contains a characteristic central scar visible on imaging scans. These growths are most often found in women between the ages of 20 and 30. Like hemangiomas, FNH tumors are generally solitary, do not cause symptoms, and rarely require treatment.
A less common type is the hepatocellular adenoma, often called a hepatic adenoma. These tumors develop from the main type of liver cells, known as hepatocytes. Adenomas are most frequently seen in women of childbearing age and have been strongly linked to oral contraceptives. While usually harmless, adenomas carry a greater risk of complications, such as rupture and bleeding, than other benign types.
Associated Symptoms and Causes
When symptoms do arise, they are the result of a tumor growing large enough to press on nearby organs or structures. This can lead to a feeling of fullness or bloating in the abdomen, discomfort, or a dull ache in the upper right quadrant. This pain can sometimes radiate to the back or shoulder. Nausea may also occur if the tumor is particularly large.
The underlying causes for these growths vary depending on the specific type of tumor. Hormonal influence is a significant factor for hepatocellular adenomas, which are linked to estrogen from oral contraceptives or hormone replacement therapy. Discontinuing these medications is often recommended if an adenoma is found. Hemangiomas are thought to be congenital, meaning they are present from birth. The cause of focal nodular hyperplasia is less clear, but it is more common in women, suggesting a possible hormonal connection.
The Diagnostic Process
An ultrasound is often the first test to detect an unexpected mass in the liver, frequently found during an imaging study for an unrelated reason. Following this initial discovery, more advanced imaging is employed to better characterize the lesion. Computed tomography (CT) scans and magnetic resonance imaging (MRI) are the primary tools for this purpose.
These technologies provide detailed images of the liver, allowing radiologists to observe the tumor’s specific features. For example, a CT scan can reveal the “central scar” associated with FNH, while an MRI with a contrast agent can highlight the vascular patterns of a hemangioma. Recent MRI advancements with hepatocyte-specific contrast agents have improved the ability to distinguish between benign tumors and rule out malignancy.
In some situations where imaging results are not definitive, a biopsy may be considered. This procedure involves taking a small tissue sample from the tumor for microscopic examination. However, a biopsy is often avoided for suspected hemangiomas due to the risk of bleeding. A diagnosis is frequently made based on imaging characteristics alone.
Management and Treatment Approaches
Once a benign liver tumor is diagnosed, the most common management strategy is “watchful waiting” or active surveillance. This approach involves periodic follow-up with imaging tests like ultrasound or MRI to monitor the tumor for any changes. For many small, asymptomatic hemangiomas and FNH, this is the only action needed, as they pose little risk and often remain stable.
Intervention becomes a consideration under specific circumstances. Treatment is recommended if a tumor causes persistent symptoms or grows rapidly. For hepatocellular adenomas, treatment is advised for larger tumors (typically over 5 cm) due to the increased risk of spontaneous rupture and hemorrhage, a potentially life-threatening complication.
When treatment is necessary, the primary method is surgical removal, also known as resection. Depending on the tumor’s size and location, this can be done through a traditional open surgery or a minimally invasive laparoscopic approach. In very rare cases with extremely large tumors that cannot be safely removed, other options like liver transplantation may be considered.