Focal Nodular Hyperplasia (FNH) is a common, non-cancerous growth found in the liver. This condition represents a benign liver lesion, meaning it is not malignant and does not spread to other parts of the body.
Focal Nodular Hyperplasia Explained
Focal Nodular Hyperplasia is a benign tumor or lesion that forms in the liver. It is not considered a type of cancer and rarely causes any problems. FNH is thought to arise from an unusual formation of an artery within the liver, causing nearby liver cells to grow larger than they normally would. This growth typically forms a well-defined lesion, often characterized by a distinctive central scar composed of different tissue types. It is the second most common benign liver tumor.
The exact cause of FNH is not fully understood, but current theories suggest it results from a hyperplastic reaction to congenital vascular malformations or other vascular anomalies within the liver. While hormones like estrogen were once considered a factor, this association has not been definitively proven. FNH is more frequently found in women, particularly those between 20 and 50 years old. Most individuals with FNH have a single, small lesion, typically less than 5 cm across, though multiple lesions can occur in about 20-30% of cases.
Addressing Cancer Concerns
Focal Nodular Hyperplasia is overwhelmingly considered a benign lesion with virtually no malignant potential. It does not transform into liver cancer or any other type of malignancy. The cells within an FNH nodule are polyclonal, which supports its classification as a benign condition. This means the growth is a collection of normal liver cells that have simply overgrown in a localized area, rather than abnormal cells with the capacity to become cancerous.
It is important to differentiate FNH from other liver lesions, such as liver adenomas, which do carry a risk of malignant transformation. Unlike adenomas, FNH lesions are stable and do not progress to cancer. The distinct cellular and structural characteristics of FNH, including the presence of normal liver components and the specific central scar, help medical professionals distinguish it from potentially cancerous growths. Therefore, a diagnosis of FNH generally offers reassurance regarding the risk of liver cancer.
Identifying and Tracking FNH
Focal Nodular Hyperplasia is most often discovered incidentally when imaging scans of the abdomen are performed for other medical conditions. Most individuals with FNH do not experience any symptoms. Diagnostic methods primarily rely on non-invasive imaging techniques such as magnetic resonance imaging (MRI), computed tomography (CT) scans, and ultrasound. These imaging modalities can reveal the characteristic appearance of FNH, including its well-defined borders and the presence of a central scar in many cases.
A liver biopsy is usually not required for diagnosis due to the distinct features visible on imaging, which allow doctors to confidently identify FNH. In some instances, a central scar may not be apparent on scans, or other features might overlap with different liver conditions, making a definitive diagnosis challenging. Once FNH is confirmed, extensive follow-up imaging is often not needed, particularly if the lesion is asymptomatic and its diagnosis is certain. Monitoring is typically reserved for cases with diagnostic uncertainty or if the lesion shows unusual growth.
Living with FNH
Most individuals diagnosed with Focal Nodular Hyperplasia do not experience symptoms and do not require any specific treatment. The presence of FNH generally does not affect overall liver function or health. Surgical removal of FNH is rarely indicated. It is usually considered only in very specific situations, such as when a very large lesion causes noticeable symptoms like abdominal pain or a feeling of fullness.
Surgery may also be considered in rare instances where there is ongoing diagnostic uncertainty and other possibilities cannot be ruled out. For the vast majority of people, living with FNH simply means knowing it is present. The condition typically remains stable in size over time, and it does not impact daily life or necessitate lifestyle changes.