Angiomyolipoma is a benign tumor of fat and muscle tissue that is particularly common in the kidney and occasionally occurs in the liver. Angiomyolipoma seldom produces symptoms, and they may bleed or grow significant enough to cause kidney failure. It is strongly predominant in individuals with tuberous sclerosis, a hereditary condition in which the kidneys, brain, eyes, heart, lungs, and skin develop benign tumors. While the exact cause of the tumors is unknown, researches suggest that angiomyolipomas are caused by mutations in either the TSC1 or TSC2 genes, which controls cell growth and proliferation.


There is no occurrence of symptoms or signs in most patients with angiomyolipoma. However, some show signs and symptoms, most especially if the tumor grows in significant size that blood vessels in the angiomyolipoma ruptures. The following symptoms and signs can occur in this case:

When the blood vessels rupture in angiomyolipoma, sudden pain results in retroperitoneal bleeding, causing nausea and vomiting. Up to 20% are in shock when the patient arrives in the emergency room.


Angiomyolipoma can be detected by three methods of scanning: ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI).

  • Ultrasound: This is the standard and a common method in detecting angiomyolipoma. It is especially sensitive to fat, albeit less to solids. However, with ultrasound, precise measurements are difficult to produce, especially if the angiomyolipoma is close to the kidney’s surface.
  • CT: It is very detailed, and results are produced quickly and enable precise measurement. However, it exposes the patient to radiation, and there are risks of the kidneys being harmed by a contrast dye used to support the scanning.   
  • MRI: It is safer than CT, but many patients need sedation or general anesthesia, particularly those with learning disabilities or behavior issues seen in patients with tuberous sclerosis. A scan cannot be done quickly.

Some other angiomyolipomas contain fat, and the presence of these types is not diagnostic. Hence, a tumor developing at greater than 5 mm per year may require a biopsy for diagnosis.


Treatment for angiomyolipoma includes the drug everolimus (Afinitor), which can influence multiple processes involved in cell growth by blocking the human target of rapamycin (mTOR) protein. Researchers recommend that angiomyolipoma developing to 3 cm or more in diameter should be treated even though it is asymptomatic.

Another treatment for angiomyolipoma is embolization, a technique under which the blood vessels in the tumor of angiomyolipoma are closed; this method can be preventive and is recommended to use in 4 cm or larger angiomyolipomas to mitigate the chances of rupture of the vessel. Asymptomatic patients with small tumors should regularly visit their doctors and get their tumors routinely checked and monitored. This should be done to track the development of the size of the tumor.

In one year, angiomyolipomas are known to develop as quickly as 4 cm. Angiomyolipomas greater than 5 cm and those containing an aneurysm are potentially life-threatening and pose a severe risk of rupture, a medical emergency.

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