Kidney Angiomyolipoma

Medically Reviewed on 5/6/2022

Things to know about kidney angiomyolipoma

Genetic Disease
Angiomyolipomas are related to the genetic disease of tuberous sclerosis.
  • Angiomyolipomas are benign tumors of the kidney and, rarely, other organs.
  • The exact cause of angiomyolipoma is not known, but researchers suggest a genetic mutation may be responsible.
  • Angiomyolipomas are related to the genetic disease of tuberous sclerosis.
  • Signs and symptoms may not occur in many patients with benign angiomyolipomas; if they do occur, the following may be seen:
  • Angiomyolipomas are usually diagnosed with the help of CT scans, MRI scans, and ultrasound. Sometimes angiomyolipomas are found when the patient is being examined and tested for other medical problems.
  • Treatment for angiomyolipomas may include drugs such as everolimus or embolization techniques. Some patients may require kidney removal.
  • The prognosis for most benign angiomyolipomas is good, however, the prognosis decreases as the size of the benign tumor increases and the likelihood of bleeding over time increases.
  • Although it's impossible to prevent angiomyolipomas, the risk of them becoming symptomatic and/or life-threatening can be reduced by drug and embolization techniques.

What is Kidney angiomyolipoma?

Angiomyolipomas are common benign (noncancerous) tumors of the kidney composed of three types of cells: vascular cells, immature smooth muscle cells, and fat cells. These benign tumors are mainly found in the kidney, but they can also be found occasionally in the liver, and rarely in the ovary, Fallopian tube, spermatic cord, palate, and colon.

Older medical literature may refer to angiomyolipomas as hamartomas or choristomas. This article will mainly describe angiomyolipoma as related to the kidneys although very infrequently, angiomyolipomas may occur in other organs.

What are angiomyolipoma symptoms and signs?

Most people with angiomyolipomas have no symptoms or signs. However, even though they are considered to be benign tumors, some can cause symptoms and signs in patients if the tumor becomes large and/or if the blood vessels in the angiomyolipoma leak blood (rupture).

In this case, the following symptoms and signs may occur:


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What are angiomyolipoma causes and risk factors?

The exact cause of angiomyolipoma is not known. Researchers suggest that the cause of these benign tumors is a mutation in a common progenitor cell (for example, a stem cell that has the potential to develop into any of the three types of cells listed above). Angiomyolipoma tumors are associated with the inherited genetic disease tuberous sclerosis (a rare genetic disease that causes benign tumors to grow in the brain and other organs) and possibly associated with other syndromes like Sturge-Weber syndrome or neurofibromatosis. Animal experiments suggest that a high-fat, low carbohydrate diet may hasten the growth and development of angiomyolipoma tumors in rats, but it's unknown if such a diet will hasten angiomyolipoma tumor development in humans.

How do doctors diagnose angiomyolipoma?

The preliminary diagnosis of angiomyolipoma is usually done either incidentally while the patient is undergoing imaging tests for other reasons or directly by ultrasound, CT scan, and/or MRI scan. Urologists, radiologists, and emergency medicine physicians are often the first doctors to suspect and/or diagnose these tumors. In addition, ob-gyn doctors may find such tumors while doing ultrasound studies on pregnant females; angiomyolipoma bleeding problems are rare but possible in pregnancy.

What is the treatment for angiomyolipoma?

Angiomyolipoma can be treated by the drug everolimus (Afinitor) that works by blocking the human target of rapamycin (mTOR) protein to affect many processes involved in cell growth. Researchers suggest that even if asymptomatic, angiomyolipoma that grows to 3 cm or more in diameter should be treated. Another treatment is embolization (technique in which the blood vessels in an angiomyolipoma tumor are sealed off); this technique can be preventative and is suggested to be used in angiomyolipomas 4 cm in diameter or larger to reduce the risk of hemorrhage (vessel rupture). Patients with angiomyolipoma tumors that are small and asymptomatic should be routinely seen with follow-up visits and measurements of the angiomyolipoma tumor size as some may quickly develop a growth rate of up to about 4 cm per year.

What is the prognosis of angiomyolipoma?

In general, the prognosis of angiomyolipoma is good as long as the tumors don't have dilated blood vessels or grow rapidly. However, the prognosis decreases if the tumor becomes very large or compromises the kidney's function so that it may need to be removed or the patient may require dialysis. In addition, if the patient develops a hemorrhage, the prognosis, if the patient is not diagnosed and quickly treated, is fair to poor.

Is it possible to prevent angiomyolipoma?

Although it is not possible to prevent angiomyolipomas from developing, it is possible to reduce the possibility that they can cause serious problems. For example, asymptomatic angiomyolipoma can be treated before they have a chance to come symptomatic, thus preventing angiomyolipoma symptoms and signs.

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Medically Reviewed on 5/6/2022
Flum, A.S., et al. "Update on the diagnosis and management of renal angiomyolipoma." J. Urol 195 (4 Pt 1) April 2016: 834-846. <>.