What Is Renal Angiomyolipoma?
Renal angiomyolipoma is a tumor that occurs in the kidney. This tumor is mostly benign or non-cancerous in nature. The tumor occurs when there is uncontrolled growth or multiplication of the cells. An angiomyolipoma is the growth of smooth muscles, fat components, and blood vessels. They are one of the most common renal tumors. Hemorrhage (bleeding from a ruptured blood vessel) is the most common side effect of this condition. The occurrence of renal angiomyolipoma is not based on familial inheritance. In very rare cases, this condition can be a part of the tuberous sclerosis complex (TSC). TSC is a condition wherein numerous tumors develop all over the body. TSC may occur due to mutations in the TSC1 or TSC2 gene. These proteins are tumor suppressive in nature.
What Causes Renal Angiomyolipoma?
Renal angiomyolipoma occurs due to mutations in the TSC1 and TSC2 genes. The proteins in this gene are tumor suppressive in nature. They prevent the excessive multiplication of cells. These genes synthesize a protein called tuberin, a protein that controls the growth and multiplication of the cells. When the synthesis of tuberin is affected, there is an uncontrolled proliferation of the cells.
What Other Conditions Are Associated With Renal Angiomyolipoma?
The other conditions that are associated with renal angiomyolipoma are-
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Tuberous sclerosis complex.
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Neurofibromatosis type 1 (A hereditary condition with multiple brown (caf-au-lait spots on the skin).
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Von Hippel - Lindau disease (A rare genetic condition that causes benign tumors in multiple parts of the body).
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Lymphangioleiomyomatosis (A condition caused by the growth of smooth muscle tissue in the lungs).
What Are the Symptoms of Renal Angiomyolipoma?
Most cases of renal angiomyolipoma are asymptomatic in nature. Many cases of angiomyolipoma are discovered accidentally during a routine investigation of the kidney. The most symptomatic cases of angiomyolipoma are due to hemorrhage of the tumor. However, this occurs in less than 15 % of the cases. This type of hemorrhage is referred to as retroperitoneal hemorrhage. This condition occurs when a part of the tumor detaches from the whole mass and enters the abdominal cavity. Retroperitoneal hemorrhage can be life-threatening if left unattended. The other symptoms of renal angiomyolipoma can incle the following-
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Pain: One may experience pain in the hips, lower back, and sides due to the presence of this tumor. The pain can be acute or intermittent in nature. Most cases have a dull pain instead of a sharp pain.
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Anemia: The blood reports of a person affected with this condition could be indicative of anemia or decreased red blood cell levels. The anemia could be due to the blood loss experienced in the hemorrhage.
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Presence of a Lump: Sometimes, a lump could be felt on the lower back. This lump could be persistent for some time till it gets noticed by the doctor or the person. The lumps are mostly painless in nature.
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Hypertension: The tumor could cause a sudden rise in blood pressure. Blood pressure is a result of the tumor that alters the functioning of the kidney.
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Hematuria: Hematuria is a condition in which there is the presence of blood in urine. This could be due to the hemorrhage associated with the tumor.
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Urinary Tract Infection: Urinary tract infection is a common symptom of renal angiomyolipoma.
How Is Renal Angiomyolipoma Diagnosed?
Most cases of renal angiomyolipoma are diagnosed when it is discovered accidentally. It can be diagnosed while checking for other conditions of the kidney or as a part of a routine investigation. When symptomatic, the following tests can be performed to check for renal angiomyolipoma-
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Ultrasound of the Kidney: Ultrasound of the kidney can be performed to check for the presence of any soft tissue swelling, such as a tumor. Ultrasound uses sound waves to diagnose various conditions of hollow organs.
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CT (Computed Tomography) Scan: CT scan is performed when the cross-section of an organ is required for diagnosing various conditions. CT scan is performed in the case of renal angiomyolipoma to check for the presence of any tumor-like growth.
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MRI (Magnetic Resonance Imaging) Scan: An MRI is useful in diagnosing various conditions that involve soft tissues.
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Genetic Testing: Genetic testing can be done to check for abnormalities in the TSC gene, which is responsible for tumor lysis.
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Biopsy: A biopsy is performed to check for the nature of the tumor. For this, the sample tissue can be obtained from the tumor that is removed from the kidney by a surgical procedure. The presence of fat in the sample tissue is a characteristic feature of renal angiomyolipoma. A biopsy is essential to check for the malignancy of the tumor. Malignancy of the tumor is ascertained by the arrangement and morphology of the cells.
How Is Renal Angiomyolipoma Treated?
The treatment of renal angiomyolipoma is dependent on the stage of the condition. Some cases of angiomyolipoma may not require any treatment at all. Some cases of this condition may even require surgery. If the angiomyolipoma is asymptomatic, the doctor may advise one to wait and watch. However, the doctor may perform certain tests at regular intervals to monitor the progress of the disease.
The doctor may perform surgery if the condition is symptomatic and also if malignancy is confirmed. If the condition is symptomatic, the doctor may suggest the following treatment to be undertaken-
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Medications: The doctor may prescribe medications such as mTOR inhibitors. This acts on the genetic mutation of the TSC gene. Such medications come under the category of targeted therapy.
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Selective Renal Artery Embolization: This is a minimally invasive procedure that targets the blood supply of the tumor. A catheter is inserted into the tumor, and its blood supply is cut off. This procedure helps in reducing the size of the tumor.
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Minimal Surgery: Minimal surgery can be performed to remove the tumor mass. This surgery aims to leave behind as many organs as possible. This procedure is also known as nephron-sparing surgery.
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Complete Nephrotomy: It is an invasive surgery in which the entire kidney is removed. This procedure is undertaken when the tumor is very large, and surgery to remove it can cause extreme loss of tissue mass.
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Cryoablation: Ablation uses extreme temperatures, such as hot and cold, to destroy the tumor tissue. In the place of temperature, radiofrequency can also be used.
Conclusion:
Angiomyolipoma is a benign tumor of the kidney. Most cases of these conditions are asymptomatic. They may be diagnosed during a routine investigation or while checking for other conditions. However, there could be some symptoms of this condition, such as pain, high blood pressure, and UTIs. When diagnosed early in the disease, the prognosis of this condition is better.
