An atypical hemangioma is a benign blood vessel growth that looks unusual on imaging scans, making it harder to distinguish from something more serious like cancer. Regular hemangiomas are among the most common benign tumors found in the spine and liver, and they have a predictable appearance on MRI or ultrasound. Atypical hemangiomas share the same underlying biology but lack those classic imaging features, which is what earns them the “atypical” label and often prompts additional testing.
How It Differs From a Typical Hemangioma
A typical hemangioma contains a mix of blood vessels and fatty tissue. That fatty component gives it a distinctive bright signal on MRI scans, making it easy for radiologists to identify with confidence. Atypical hemangiomas have much less fat and more blood vessels. This shift in composition changes how they appear on imaging: instead of lighting up brightly on all MRI sequences, they look darker on certain views and enhance more intensely when contrast dye is injected.
That imaging pattern is the core problem. A dark signal on one MRI sequence combined with strong contrast enhancement can mimic the appearance of metastatic cancer that has spread to the bone or liver. This is why an atypical hemangioma often triggers follow-up scans or even a biopsy, not because doctors suspect cancer, but because they need to rule it out.
Where Atypical Hemangiomas Occur
Spine
The spine is the most commonly discussed location. Vertebral hemangiomas are extremely common, showing up incidentally on roughly 10% of MRI scans. Atypical or aggressive vertebral hemangiomas account for less than 1% of all spinal hemangiomas. They can appear anywhere along the spine but tend to cause the most concern when they expand beyond the vertebral body into surrounding structures.
Signs of a more aggressive pattern include erosion of the bone’s outer layer, expansion into the back portions of the vertebra, soft tissue extending outside the bone, or encroachment into the spinal canal itself. These features don’t mean the growth is cancerous. They mean it’s behaving more aggressively than a typical hemangioma and may need closer monitoring or treatment.
Liver
Hepatic (liver) hemangiomas are the most common benign liver tumors, and most are easily identified on imaging. Atypical liver hemangiomas can take on several unusual enhancement patterns when viewed with contrast-enhanced ultrasound or MRI. Some fill with contrast dye from the inside out (centrifugal pattern) rather than the expected outside-in pattern. Others show only partial enhancement, ring-like enhancement around the edges, or a slow spoke-wheel pattern. In some cases, the lesion shows almost no enhancement at all.
These variations matter because they can overlap with the appearance of other liver masses, including malignant ones. Radiologists use the specific timing and direction of contrast filling to narrow the diagnosis. For instance, the inside-out enhancement pattern needs to be carefully distinguished from a different benign growth called focal nodular hyperplasia, which has its own characteristic central filling pattern.
Symptoms to Be Aware Of
The vast majority of hemangiomas, typical or atypical, cause no symptoms at all. They’re usually discovered by accident during imaging done for an unrelated reason. When atypical vertebral hemangiomas do cause symptoms, the onset can range from two months to two years before diagnosis.
In the spine, symptoms develop in fewer than 2% of cases. When they do appear, they fall into a few categories. Back or neck pain is the most straightforward. More concerning symptoms arise when the growth expands enough to press on nerves or the spinal cord. In a study of 118 symptomatic vertebral hemangiomas, myelopathy (spinal cord compression causing weakness, numbness, or coordination problems in the limbs) was present in 73 cases, while nerve root irritation causing radiating pain occurred in 15 cases. About 55% of symptomatic cases showed an aggressive pattern with possible invasion into the spinal canal or surrounding soft tissue.
Liver atypical hemangiomas rarely cause symptoms unless they grow quite large. When they do, symptoms tend to be vague: a sense of fullness or discomfort in the upper abdomen.
How Doctors Tell It Apart From Cancer
The central challenge with atypical hemangiomas is that they can look like metastatic disease on standard imaging. Radiologists use several strategies to make the distinction.
Dynamic contrast-enhanced MRI is one of the most useful tools, particularly in the spine. This technique tracks how quickly contrast dye flows into and out of a lesion over time. Metastatic tumors tend to absorb contrast rapidly, reach a high peak, and then show a clear washout as the dye leaves. Atypical hemangiomas behave very differently: they show minimal, slow enhancement with no significant washout. In one study, 88% of atypical hemangiomas displayed this characteristic slow, low-level enhancement curve. The blood flow measurements within atypical hemangiomas are also significantly lower than in metastatic lesions, even when the two look nearly identical on standard MRI views.
For liver lesions, the timing and pattern of contrast filling on ultrasound or MRI help narrow the diagnosis. When imaging alone isn’t definitive, a biopsy may be recommended to examine the tissue directly under a microscope.
Treatment and Management
If an atypical hemangioma is asymptomatic and imaging confirms it’s benign, no treatment is needed. Many people live their entire lives with one and never know it. The initial management for a confirmed atypical hemangioma that isn’t causing problems is the same as for a typical hemangioma: no intervention, with periodic imaging if your doctor wants to track its size.
Treatment becomes necessary when symptoms develop, particularly neurological symptoms in spinal cases. The options depend on severity and how quickly symptoms are progressing.
- Pain management: For cases where back pain is the only symptom, medical therapy with pain medication and monitoring is often the first step.
- Vertebroplasty: A minimally invasive procedure where bone cement is injected into the affected vertebra. This stabilizes the bone and can provide quick pain relief. It’s best suited for cases with pain or vertebral body damage but no neurological problems.
- Radiation therapy: Used to shrink the growth and relieve pressure, particularly when surgery carries high risk.
- Embolization: A procedure that cuts off blood supply to the hemangioma. It’s sometimes performed before surgery to reduce the risk of heavy bleeding during the operation.
- Surgery: Reserved for cases with worsening neurological function, significant spinal canal narrowing, or spinal instability. This can range from partial removal of bone to relieve pressure on the spinal cord, to more extensive procedures involving removal and reconstruction of the affected vertebra in severe cases.
No standardized treatment guidelines exist for atypical hemangiomas. Decisions are made case by case, weighing the severity of symptoms against the risks of each intervention. For the small number of people who do need treatment, the goal is relieving pressure on neural structures and stabilizing the spine, not eliminating a cancer risk. These growths are benign, and the prognosis after appropriate treatment is generally favorable.