Angiomyolipoma natural history, complications and prognosis

If left untreated, small angiomyolipomas and those without dilated blood vessels (aneurysms) cause few symptoms. Small angiomyolipomas are associated with the most favorable prognosis. Common complications of angiomyolipoma include infection, hemorrhage, and shock.

• If left untreated, small angiomyolipomas and those without dilated blood vessels (aneurysms) cause few problems.
• Angiomyolipomas grow as rapidly as 4 cm in one year so regular surveillance is necessary depending upon the size of the tumour.^[1][2]
  • Angiomyolipoma, less than 2cm, surveillance every 3-4 years by renal ultrasound.
  • Angiomyolipoma 2-4 cm, annual renal ultrasound recommended.
  • Angiomyolipoma more than 4 cm, and of Epithelioid variant, renal ultrasound every 6 months initially and annual thereafter once stabilized, in case if it is not resected.
  • Angiomyolipoma with high risk of malignant transformation, should undergo whole body CT/MRI, 6 months post resection and then yearly for at least 5 years.

• It has been observed in some studies that the female sex hormones has positive impact on the size of the angiomyolipoma.
• There has been increased growth and hemorrhagic complications seen during the pregnancy as well as after treatment with exogenous hormonal therapy.^{[3][4][5][6][7]}
• Due to increased rate of growth of angiomyolipoma and increased risk of its rupture, it is advised to use estrogen carefully in these patients, and frequent imaging surveillance every six months initially and annual thereafter, once established, is recommended.

• Common complications of angiomyolipoma include:^[8]
  • Infections
  • Urinary obstruction
  • End stage renal failure, in case of bilateral angiomyolipoma
  • Intestinal obstruction
  • Shock
  • Hemorrhage
  • Rarely, it can transform into malignant angiomyolipoma, especially if related to Tuberous Sclerosis

• Small angiomyolipomas are associated with the most favorable prognosis. An angiomyolipoma larger than 5 cm and those containing an aneurysm pose a significant risk of rupture, which is a medical emergency as it is potentially life-threatening. Cumulative risk of hemorrhage is estimated to be:^[9]
  • 10% among males
  • 20% among females

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