Angiomyolipoma of the Kidney

What is an angiomyolipoma?

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.

Who might get angiomyolipoma in a kidney?

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:

• Lymphangioleiomyomatosis (LAM).
• Tuberous sclerosis complex (TSC).

How common is angiomyolipoma in kidneys?

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.

Are there different types of angiomyolipomas?

There are three types of AML kidney, based on the type of cells and tissue the tumor contains:

• Classic (triphasic) AMLs: Most angiomyolipomas (AMLs) contain three types of tissue — blood vessels, fat and smooth muscle tissue.
• Monophasic AMLs: Some AMLs contain almost all of one type of tissue, such as smooth muscle or fat.
• Epithelioid angiomyolipomas: These angiomyolipomas are mostly made up of cells that line your kidney’s blood vessels (epithelioid cells). These tumors may be more likely to become cancer.

How serious is an angiomyolipoma?

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.

How fast does an angiomyolipoma grow?

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.

What causes angiomyolipomas?

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.

What are the symptoms of angiomyolipomas?

Many people with angiomyolipomas don’t have any symptoms at all. If the mass grows large, it may cause symptoms including:

• Anemia due to bleeding.
• Fever.
• Flank pain or kidney pain due to bleeding around your kidney.
• High blood pressure (hypertension).
• Nausea and vomiting.

How is an angiomyolipoma diagnosed?

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.

What tests diagnose angiomyolipoma?

Healthcare providers may recommend imaging tests, including:

• CT scan.
• MRI.
• Ultrasound.

Some types of angiomyolipomas can look like kidney cancer during imaging tests. Your healthcare provider may recommend a kidney biopsy to be sure.

How do I know if an angiomyolipoma needs treatment?

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.

How are angiomyolipomas treated?

Your healthcare provider may recommend treatment to stop the tumor’s growth or to remove it. You might have:

• Ablation therapy: During ablation therapy, healthcare providers use energy (radiofrequency waves), heat or cold gas to destroy angiomyolipomas.
• Arterial embolization: Your provider makes a small incision in your inner thigh and uses a thin tube (catheter) to insert tiny beads. These beads block blood flow to the angiomyolipoma to shrink it, reduce its blood flow and minimize the risk of bleeding.
• Complete nephrectomy: During a nephrectomy, surgeons remove the entire kidney that contains the angiomyolipoma.
• Partial nephrectomy: Surgeons remove the part of your kidney that contains the angiomyolipoma but not the entire kidney. You might have open partial nephrectomy or robotic partial nephrectomy.

Are there complications or side effects of angiomyolipoma treatment?

There are some risks after kidney surgery and other angiomyolipoma therapies, including:

• Bleeding.
• Infection.
• Scars.

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.

How long does it take to recover from angiomyolipoma treatment?

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.

Can I prevent angiomyolipomas?

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.

Are there other conditions that put me at higher risk for angiomyolipomas?

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.

What can I expect if I have angiomyolipoma?

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.

Are there long-term effects from angiomyolipoma?

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.

Can I get angiomyolipoma more than once?

Yes, an angiomyolipoma can regrow after treatment. It’s also possible to have multiple angiomyolipomas and to develop AMLs in both kidneys.

Can angiomyolipoma be cancerous?

Epithelioid angiomyolipoma can sometimes develop into cancer. Your provider will monitor you closely and discuss the next steps in your care if that happens.

If I have angiomyolipoma, how often should I see my healthcare provider?

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.

When should I call my healthcare provider?

Call your provider right away if you develop any new symptoms such as:

• Abdominal pain.
• Back pain.
• Fever.
• Nausea and vomiting.
• Hematuria (blood in the urine).

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.