Focal Nodular Hyperplasia: Symptoms, Causes, Diagnosis, Treatment and Outlook
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
TL;DR
Focal nodular hyperplasia (FNH) is a benign, noncancerous liver tumor characterized by normal liver cells growing in an abnormal pattern around a distinctive central scar. As the second most common type of noncancerous liver growth, FNH typically does not cause symptoms and is often discovered incidentally during imaging tests for unrelated health concerns. Unlike cancerous tumors, FNH lesions do not spread to other organs or increase the risk of liver cancer. While most cases require no treatment other than periodic monitoring, the condition is most prevalent in females aged 35 to 50. The long-term outlook for individuals with FNH is excellent, as the lesions often remain stable or shrink over time without affecting overall liver function.
Quick Answer: What is Focal Nodular Hyperplasia?
Focal nodular hyperplasia (FNH) is a noncancerous liver growth made of healthy liver cells that have grown in a disorganized way, often around a central star-shaped scar. It is a regenerative process, likely triggered by unusual blood flow patterns in the liver, rather than uncontrolled cell growth. FNH is not precancerous and does not harm the liver's ability to function. Most people with FNH have no symptoms and require no treatment beyond occasional follow-up scans. It is most frequently diagnosed in women between the ages of 35 and 50 and is often found by chance during an MRI or CT scan.
What Is Focal Nodular Hyperplasia?
Focal nodular hyperplasia is a benign (noncancerous) liver tumor that represents the body's response to localized changes in blood flow. It is composed of normal, healthy liver cells (hepatocytes), bile ducts, and connective tissue, but they are arranged in an abnormal, nodular pattern. The hallmark feature of FNH is a "central scar," which is a star-like area of fibrous tissue in the middle of the lesion that contains blood vessels.
FNH is the second most common benign liver tumor, following hemangiomas. These lesions do not have the potential to become malignant (cancerous) and do not spread to other parts of the body. While most individuals have only a single lesion, it is possible to develop multiple FNH growths.
FNH at a Glance
Tumor type: Benign (noncancerous)
Composition: Normal liver cells with a central fibrous scar
Prevalence: Second most common benign liver growth
Primary demographic: Females, ages 35 to 50
Cancer risk: None (not precancerous)
Symptoms of Focal Nodular Hyperplasia
The vast majority of people with FNH never experience symptoms. Because the lesions are typically small and grow slowly, they rarely interfere with the liver or surrounding organs. Symptoms are only likely to occur if a lesion becomes exceptionally large or begins to press on nearby structures.
When symptoms do manifest, they are usually mild and non-specific:
Abdominal pain: Discomfort or a dull ache in the upper right side of the abdomen.
Fullness: A sensation of pressure or feeling full after eating small amounts.
Fatigue: General tiredness, though this is less common.
Visible lump: In very rare cases, a large lesion may be felt as a lump in the abdomen.
Causes and Risk Factors
The precise cause of focal nodular hyperplasia remains unknown, but medical researchers believe it is a regenerative response to an underlying vascular (blood vessel) abnormality.
Pathogenesis
FNH is thought to form when an abnormal artery within the liver changes the way blood flows through a specific area. This increased blood flow stimulates healthy liver cells to grow faster than the surrounding tissue, creating the nodular lesion. Because it is a response to blood flow changes rather than a genetic mutation, FNH is considered a regenerative process rather than a true neoplasm (abnormal growth).
Risk Factors
While FNH can affect anyone, certain factors increase the likelihood of developing these lesions:
Biological sex: FNH is significantly more common in females than in males.
Age: Most diagnoses occur between the ages of 35 and 50.
Vascular conditions: Individuals with blood vessel differences or Budd-Chiari syndrome are at higher risk.
Associated lesions: FNH often occurs in people who already have other benign liver growths, such as hemangiomas.
Note on hormones: Although FNH is more common in women, clinical evidence has not shown that estrogen, pregnancy, or birth control pills cause the formation or growth of these lesions.
Diagnosis and Imaging
Because FNH is usually asymptomatic, it is often found "by accident" during imaging for other conditions. Accurate diagnosis is critical to ensure the lesion is not a more serious growth, such as a hepatic adenoma or hepatocellular carcinoma (liver cancer).
Diagnostic Tests
Healthcare providers rely on advanced imaging to identify the characteristic features of FNH, such as the central scar and specific blood flow patterns:
Liver MRI: Often performed with hepatocyte-specific contrast to provide the most detailed view of the lesion's composition. It identifies the central scar and cell types.
CT scan: Useful for identifying the size and location of the growth.
Contrast-enhanced ultrasound (CEUS): A specialized ultrasound that uses microbubbles to visualize blood flow within the liver.
Blood tests: Used to rule out impaired liver function; results are typically normal in FNH.
Blood tests are typically normal in patients with FNH, as the lesion does not affect liver function. A liver biopsy is rarely necessary and is only considered if imaging results are inconclusive.
Treatment and Management
For most people, the best treatment for focal nodular hyperplasia is no treatment at all. If the diagnosis is certain and the patient has no symptoms, healthcare providers typically recommend a "watch and wait" approach.
Monitoring
Providers may schedule follow-up imaging scans every 12 months to ensure the lesion remains stable in size and appearance. If the lesion stays the same or shrinks, further follow-up may eventually be discontinued.
Active Treatment Options
Treatment is only considered if the lesion is causing significant pain, pressing on organs, or if the diagnosis remains uncertain after imaging. Options include:
Liver resection: Surgical removal of the part of the liver containing the lesion.
Arterial embolization: A procedure to block the blood supply to the lesion, causing it to shrink.
Radiofrequency ablation: Using heat to destroy the abnormal liver cells.
Outlook and Prognosis
The prognosis for focal nodular hyperplasia is excellent. These lesions are not dangerous, do not become cancerous, and do not shorten life expectancy. In many cases, FNH lesions remain the same size for years or may even shrink over time. Once a definitive diagnosis is made, most patients can return to their normal lives without any impact on their long-term health or liver function.
FAQ: Frequently Asked Questions
Can focal nodular hyperplasia turn into cancer?
No. FNH is a benign, noncancerous growth made of normal liver cells. It does not have the potential to become malignant or lead to liver cancer.
Do I need to stop taking birth control if I have FNH?
Generally, no. Research has not shown a direct link between birth control pills and the growth of FNH lesions. You should discuss your specific situation with your healthcare provider.
Is surgery always necessary for FNH?
No. Surgery is rarely needed and is only considered if the lesion is very large, causing pain, or if the diagnosis is not 100% clear from imaging.
What is the "central scar" in FNH?
The central scar is a star-shaped area of fibrous tissue in the middle of the FNH lesion. It contains blood vessels and is a key feature that helps doctors distinguish FNH from other liver growths.
Does FNH cause liver failure?
No. FNH is made of healthy liver cells and does not interfere with the liver's overall ability to function or filter blood.
How common is focal nodular hyperplasia?
It is the second most common benign liver tumor, occurring in approximately 3% to 5% of the general population, though many people never know they have it.
Can children get FNH?
Yes, FNH can occur in children, although it is much more common in adults between the ages of 35 and 50.
What happens if an FNH lesion ruptures?
Rupture or bleeding of an FNH lesion is extremely rare. Unlike some other liver tumors, FNH is generally very stable and does not pose a significant risk of spontaneous bleeding.
Does FNH cause weight loss?
No, FNH is not typically associated with weight loss. If you are experiencing unexplained weight loss along with liver symptoms, your doctor will look for other potential causes.
How often should I get follow-up scans?
If your doctor recommends monitoring, follow-up scans are typically performed every 12 months, though this frequency may decrease if the lesion remains stable.
Is FNH hereditary?
There is no strong evidence to suggest that focal nodular hyperplasia is a hereditary condition passed down through families.
Can I drink alcohol if I have FNH?
Moderate alcohol consumption is generally fine, as FNH does not affect liver function. However, you should always follow your doctor's advice regarding liver health.
What is the difference between FNH and a hemangioma?
Both are benign liver growths. A hemangioma is made of a tangle of blood vessels, while FNH is made of liver cells growing around a central scar. Hemangiomas are the most common benign liver growth, and FNH is the second most common.
Can FNH cause yellowing of the skin (jaundice)?
No. Jaundice is a sign of liver dysfunction or bile duct blockage, neither of which is typically caused by focal nodular hyperplasia.
Is a liver biopsy painful?
If a biopsy is needed, it is performed under local anesthesia or sedation. While there may be some discomfort, it is generally a well-tolerated procedure. However, most FNH cases are diagnosed via imaging alone.
References
Cleveland Clinic. Focal Nodular Hyperplasia. (2026, March 19). https://my.clevelandclinic.org/health/diseases/focal-nodular-hyperplasia
American Liver Foundation. Benign Liver Tumors. (2025, June 11).
British Liver Trust. Focal nodule hyperplasia. (2023, October 8).
StatPearls. Focal Nodular Hyperplasia. (2022, September 26).
Journal of Clinical and Translational Hepatology. Focal Nodular Hyperplasia Review. (2024, January 2).
Medical Disclaimer: The information provided in this article is for educational purposes only and should not be considered medical advice. If you have concerns about a liver growth or abdominal pain, consult a qualified healthcare provider for diagnosis and treatment.
Comments