Angiomyolipoma is a condition in which benign tumors form in your kidney. You may have no symptoms, or you may have anemia, fever, pain or high blood pressure. Tumors that grow may need treatment such as embolization or surgery to reduce the risk of bleeding.
In angiomyolipoma (AML) — sometimes called renal angiomyolipoma — cells inside your kidney grow in ways that aren’t typical. These cells form a mass called a tumor (neoplasm).
Angiomyolipomas are benign (not cancerous). Fat (adipose tissue), smooth muscle and blood vessels make up these tumors. If the tumor grows too large, it may cause symptoms such as bleeding, anemia, fever and kidney pain.
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Anyone can get an angiomyolipoma. But the condition is more common in women, especially those 40 to 60 years old.
Angiomyolipomas also happen more often in people who have certain health conditions, including:
Angiomyolipomas occur in less than 1% of the general population. But they are the most common benign kidney tumor. And they're very common in people with tuberous sclerosis complex — more than half of people with TSC develop angiomyolipomas.
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There are three types of AML kidney, based on the type of cells and tissue the tumor contains:
Many people with angiomyolipoma don’t know they have the condition. If the tumor grows larger than about 4 centimeters (about the size of a walnut), it could cause bleeding (hemorrhage). This bleeding can be life-threatening if it’s not treated.
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Many classic angiomyolipomas don't grow at all. If these tumors do get larger, growth usually happens very slowly. On average, these tumors grow at about 0.19 centimeters — about one-sixteenth of an inch — each year. However, during pregnancy, these tumors can grow more rapidly. Therefore if you have an angiomyolipoma and are considering having a child, it may be prudent to treat the angiomyolipoma prior to pregnancy.
Healthcare providers aren’t sure why these tissues form a mass in your kidney. But researchers think certain changes (mutations) in genes may play a role.
Many people with angiomyolipomas don’t have any symptoms at all. If the mass grows large, it may cause symptoms including:
Your healthcare provider may notice a tumor while doing imaging tests for another health condition. If you have symptoms, they may order tests to learn more about what’s causing the symptoms.
Healthcare providers may recommend imaging tests, including:
Some types of angiomyolipomas can look like kidney cancer during imaging tests. Your healthcare provider may recommend a kidney biopsy to be sure.
Some people with angiomyolipoma don’t need any treatment. Your care plan depends on the size of the tumor, whether you have any symptoms and whether you plan to become pregnant.
You’ll see your healthcare provider usually once a year to check the tumor’s growth. If the tumor is larger than 4 centimeters, your provider may recommend treatment.
Your healthcare provider may recommend treatment to stop the tumor’s growth or to remove it. You might have:
There are some risks after kidney surgery and other angiomyolipoma therapies, including:
Sometimes, kidney failure can happen after treatment or surgery for kidney conditions. Your healthcare provider will discuss these risks with you before treatment and take steps to help reduce risk. If kidney failure happens, your provider will develop a care plan to manage symptoms and help you feel your best.
If you had a complete or partial nephrectomy, you may need to stay in the hospital for a few days. Healthcare providers will do kidney function tests and make sure you are healing well.
After ablation therapy or arterial embolization, you may need to stay in the hospital for a few hours or overnight.
There’s no sure way to prevent angiomyolipomas. These tumors often develop spontaneously. A spontaneous occurrence means there is no particular reason why the AML happened.
If you have tuberous sclerosis complex or lymphangioleiomyomatosis, you are at higher risk for an angiomyolipoma. Talk to your healthcare provider about steps you can take to monitor your health and reduce your risk.
If you have angiomyolipoma and don’t have symptoms, expect to see your healthcare provider about once a year. You’ll have imaging tests to see if the tumor is growing.
If you’re experiencing symptoms, your healthcare provider may recommend treatment to prevent possible bleeding.
If angiomyolipomas increase in size, there is a danger that they could bleed or rupture. Your healthcare provider will check the tumor’s size and recommend treatment if you are at risk.
Yes, an angiomyolipoma can regrow after treatment. It’s also possible to have multiple angiomyolipomas and to develop AMLs in both kidneys.
Epithelioid angiomyolipoma can sometimes develop into cancer. Your provider will monitor you closely and discuss the next steps in your care if that happens.
Stick to the care plan you and your healthcare provider develop. See your provider for all follow-up visits to check if the tumor is growing.
Call your provider right away if you develop any new symptoms such as:
A note from Cleveland Clinic
Angiomyolipoma is a condition in which noncancerous (benign) tumors form in your kidney. You may not notice any symptoms at all. Your healthcare provider will check the tumor each year to see if it is growing. Tumors larger than 4 centimeters may need treatment to prevent the risk of bleeding. Talk to your healthcare provider about what you should do if you have symptoms.
Last reviewed on 01/30/2022.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy