A kidney angiomyolipoma is a rare, noncancerous growth made of fat, muscle, and blood vessels. These tumors are usually benign and often stay small without causing health issues.
Most people do not realize they have one until it is found during an imaging test for another reason. Because they rarely cause symptoms, many are discovered entirely by accident during routine checkups. However, larger tumors or those that begin to bleed can lead to noticeable discomfort or lower back pain. You might also notice blood in your urine if the growth becomes significant or unstable.
Managing this condition typically involves working with a urologist or nephrologist to monitor the tumor. Depending on its size, your doctor may suggest regular observation or surgical intervention.
Main symptoms
The main symptoms of kidney angiomyolipoma are:
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Lower back pain
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Pain in the side (flank pain)
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Abdominal pain or discomfort
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High blood pressure
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Blood in the urine
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Urinary tract infections
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Anemia
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Kidney failure
Most kidney angiomyolipomas do not cause any physical signs or discomfort. Symptoms typically only develop if the tumor grows significantly or starts to bleed. If you experience these signs, it is important to see a primary care doctor or a kidney specialist for a proper diagnosis and treatment plan.
Additionally, these tumors can sometimes cause bleeding in the area surrounding the kidney, a condition known as Wunderlich syndrome. This specific complication often leads to sudden side pain, a lump you can feel, or blood in the urine.
Severe bleeding from a kidney angiomyolipoma is a medical emergency that can lead to hypovolemic shock. Symptoms include a sharp drop in blood pressure, fainting, and skin that feels cold or looks very pale. If these occur, go to an emergency room immediately for stabilization, which may include blood transfusions or surgery to stop the hemorrhage.
Is kidney angiomyolipoma cancer?
A kidney angiomyolipoma is not cancer, as it is a benign tumor made of muscle, fat, and blood vessels. However, a specific subtype called an epithelioid angiomyolipoma carries a higher risk of behaving like a malignant tumor.
Confirming a diagnosis
Doctors usually diagnose these tumors using health history and imaging tools like ultrasound, CT scans, or MRIs. A physician may also perform a kidney biopsy to confirm the tumor type and rule out other conditions like renal cell carcinoma or Wilms tumor.
Possible causes
While the exact cause is not always clear, these tumors can occur on their own or because of inherited genetic mutations in the TSC1 or TSC2 genes. According to the National Cancer Institute, kidney angiomyolipomas are also frequently associated with other hereditary conditions, including tuberous sclerosis complex and a lung disease called lymphangioleiomyomatosis.
Women are more likely to develop these tumors than men, possibly due to the influence of estrogen. Growth is often more rapid during pregnancy or while taking estrogen replacement therapy, which increases the risk of complications.
Treatment options
Treatment plans are customized by a specialist based on the tumor's size, symptoms, and growth rate. For small, stable tumors, a doctor might simply recommend a yearly imaging scan to monitor for changes.
However, if the tumor is larger than 6 cm, grows more than 2.5 mm annually, or causes chronic pain, several treatment options are available:
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Use of medications, such as everolimus or sirolimus, to help shrink tumors, especially those related to genetic conditions. Based on approvals from the U.S. Food and Drug Administration, everolimus is specifically indicated for treating renal angiomyolipomas associated with tuberous sclerosis complex when the patient does not require immediate surgery.
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Ablation therapy, using radiofrequency or cryotherapy, with the goal of destroying the tumor tissue.
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Embolization, which cuts off the tumor's blood supply and is often used during emergencies to stop active bleeding.
Additionally, a urologist may perform a surgery called a nephrectomy to remove part or all of the kidney. This is typically reserved for suspected cancer or cases where other treatments are not an option. Emergency surgery may also be required if severe bleeding occurs.