Subtypes and How They Grow

While most adult liver hemangiomas follow a predictable path, understanding how they change over time can help you make sense of your imaging reports and what to expect in the years ahead.

Common Terminology

Doctors classify liver hemangiomas based on how they look biologically. While a patient rarely needs a microscopic subtype to guide their care, you may see these terms on a report:

• Cavernous Hemangioma: This is the overwhelming majority of adult cases ^[1]. It is made of relatively large, blood-filled “caverns” or chambers lined with normal endothelial cells ^[2][3].
• Sclerosed or Sclerosing Hemangioma: This is not necessarily a separate “type,” but rather a rare, degenerative phase of a hemangioma. Over time, the blood-filled spaces can be gradually replaced by fibrosis (scar tissue) and hyalinization (a glassy, protein-rich tissue) ^[4][5]. Because it contains more scar tissue than blood, it often looks atypical on scans and can sometimes be confused with more serious conditions like liver cancer or bile duct cancer ^[6][7].

Defining a “Giant” Hemangioma

There is no single, universal rule for when a hemangioma becomes “giant.” In current medical literature, a lesion is often called giant once it exceeds 5 to 10 centimeters (about 2 to 4 inches) in its largest diameter ^[8][9]. Some older reports may use a smaller cutoff, while extremely large growths over 20 centimeters are sometimes called “enormous” ^[10][8].

How They Grow and Change

One of the most common misconceptions is that if a “tumor” grows, it must be cancer. This is not true for liver hemangiomas. Their growth is usually very slow and is not a sign of malignant transformation (turning into cancer) ^[11][12].

Growth Rates

In large observational studies of untreated adults, the “natural history” of hemangiomas varies widely:

• Many enlarge slightly over several years.
• A significant portion stay the exact same size.
• Some actually shrink.

The speed of growth often depends on your age and the starting size of the lesion. On average, smaller hemangiomas grow very slowly (e.g., 1 to 2 mm per year) ^[11]. Giant hemangiomas tend to grow slightly faster, though still generally slowly ^[11][12]. Growth tends to slow down as people get older. Importantly, differences of a few millimeters between scans can sometimes just reflect different measurement techniques or different MRI machines, rather than actual biological growth.

Spontaneous Shrinkage (Involution)

It is possible for a hemangioma to shrink on its own over time, a process called involution ^[13]. This usually happens when the blood supply to the growth naturally decreases and it turns into a sclerosed (scarred) lesion ^[14][13]. In rare cases, they can shrink dramatically.

Rapid Growth and Diagnostic Review

While slow growth is normal, rapid growth is a reason for your medical team to pause and re-evaluate. If a hemangioma grows rapidly (for example, several centimeters in a short period), it does not automatically mean you need surgery. However, rapid or atypical change should prompt a renewed diagnostic review. Your doctor will want to ensure the lesion isn’t actually a malignant mimic (especially if you have chronic liver disease or a prior history of cancer) and will check to see if the growth is increasing your risk for complications ^[15][12].