Kidney Angiomyolipoma

Angiomyolipomas are related to the genetic disease of tuberous sclerosis.

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.

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 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:

• Sudden pain (back pain or flank pain)
• Nausea
• Vomiting
• Anemia
• Hypertension
• Chronic kidney disease
• Shock (about 20% of patients that show symptoms develop shock)

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.

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.

Angiomyolipoma: ultrasound imaging

• Ultrasound is often the first imaging modality used. Angiomyolipomas typically appear on ultrasound as brighter than the surrounding kidney tissue due to their higher fat content.
• This is a key characteristic of angiomyolipomas that helps differentiate them from other renal masses.

CT and MRI scans

• CT scans are highly effective for diagnosing angiomyolipomas. They can reveal the presence of fat within the tumor, which is a hallmark of this condition. This imaging technique can also help rule out other renal tumors, such as renal cell carcinoma, which typically does not contain fat.
• MRI is another valuable tool, particularly for complex cases. Angiomyolipomas may show variable signal intensity on MRI due to their fat content[MS1] . This helps differentiate them from other renal masses.

Biopsy

• While imaging is usually sufficient for diagnosis, a biopsy may be considered in certain cases, especially if there is uncertainty about the nature of the mass or if it appears atypical.
• This is particularly relevant for smaller tumors or those that do not exhibit clear imaging characteristics typical of angiomyolipomas.

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.

Angiomyolipoma can be treated by the drug everolimus (Afinitor), which works by blocking the mammalian target of rapamycin (mTOR) protein to affect many processes involved in cell growth. Researchers suggest that even if asymptomatic (causing no symptoms), angiomyolipomas that grow to 3 cm or more in diameter should be treated. Another treatment is embolization (a 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.

Is the angiomyolipoma in the kidney serious? 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 and is not diagnosed and quickly treated, the prognosis is fair to poor.

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

• Do angiomyolipomas need to be removed? Small, asymptomatic angiomyolipomas can often be monitored with regular imaging. However, if the tumor is large (typically over 4 cm), causes symptoms, or poses a risk of bleeding, surgical removal or other treatments may be recommended to prevent complications.
• How to get rid of angiomyolipoma naturally. Angiomyolipomas are benign kidney tumors, and while there is no proven natural method for their elimination, managing their symptoms can be supported by maintaining a healthy lifestyle. This includes adhering to a balanced diet, staying well-hydrated, avoiding smoking, and controlling blood pressure. Regular monitoring through imaging is important to detect any changes. However, always consult with a health care provider for personalized advice, as some cases may require medical intervention.
• What age do people get angiomyolipomas? Angiomyolipomas can develop at any age but are most commonly diagnosed in women between 40 and 60 years, with an average age of presentation around 43 years. They can occur in individuals from 10 to 80 years old. Angiomyolipomas are notably more common in individuals with conditions such as tuberous sclerosis complex, where over 50% of those affected may develop these tumors.
• What size angiomyolipoma requires surgery? Surgery for angiomyolipomas is usually recommended when the tumor exceeds 4 cm in size, as lesions of this size carry a higher risk of complications, including bleeding and rupture, which can be life-threatening. Additionally, angiomyolipomas larger than 8 cm are generally considered for surgical intervention due to their significant potential to cause troublesome symptoms. Tumors smaller than 4 cm are usually monitored unless they cause symptoms or show significant growth.