Angiomyolipoma of the kidney is one of the benign tumors found in the kidney and consists of three different types of tissue. This means, in renal angiomyolipoma masses, there are both vascular (angio), and muscle (mayo) and adipose tissue (lipo), if you or your relatives have been diagnosed with renal angiomyolipoma, and you are looking for accurate and medical information about this benign tumor, read more.
The tumor is said to have been first identified and named by Dr. Morgan and his team in 1951.
Doctors believe that most cases of renal angiomyolipoma will not require treatment, but must be followed by a doctor.
With the advancement of medical knowledge and the emergence of new methods and advanced radiology technologies, today more than in the past, asymptomatic cases of renal angiomyolipoma are being discovered and identified.
The prevalence of renal angiomyolipoma in developed countries is 0.3% to 3%.
Renal angiomyolipoma makes up 5% of all renal tumors.
It is not just the kidneys that are affected by the tumor, doctors say angiomyolipoma can be found in organs and tissues outside the kidney, such as the liver, uterus, spleen, colon, heart, abdominal wall, back of the intestines and even in the oral mucosa.
Angiomyolipoma originates from perivascular cells. Malignant types of angiomyolipoma have also been reported in reputable medical reports.
Histology of angiomyolipoma
Three different tissues, namely adipose tissue, vascular tissue, and smooth muscle, can be seen in angiomyolipoma tumors under a microscope. Under the microscope, spindle-shaped cells are seen, along with fat cells and twisted arteries. But the tumor itself with the normal eye is a round mass with a well-defined margin that is yellow to cream-brown !! in color.
Statistics, numbers and epidemiology of renal angiomyolipoma
In the case of renal angiomyolipoma, it is said that there are two different manifestations of this benign kidney tumor:
- single type of renal angiomyolipoma tumor (sporadic form) which will have the following characteristics (eighty percent of all renal angiomyolipomas):
- The most common age for involvement with this form of angiomyolipoma is 27-72 years old.
- Average age of onset is 43 years
- Women are four times more likely to develop this form of renal angiomyolipoma than men
- This form of tumor is said to be caused by 20% of cases of a syndrome called tuberculosis. This set is transmitted as a dominant autosomal transmission. People with TS have a high potential to have benign tumors in various parts of their body, including various tissue components that doctors call hamartomas.
- non-single types of renal angiomyolipoma (twenty percent of all renal angiomyolipomas); there are bilateral in two kidneys, there are numerous in both kidneys and it is larger in size than the single form.
- The average age of onset of this form of renal angiomyolipoma is 17.
- Women are twice as likely as men to develop this form.
In general, people with tuberculosis and angiomyolipoma have a higher risk of developing malignancies than people with angiomyolipoma but no tuberculosis. Also, angiomyolipoma of the kidney grows slowly, but the growth rate is much faster in bilateral and multiple forms and it is interesting to know that hormones probably play an effective role in increasing the growth rate of renal angiomyolipoma because these tumors grow faster in pregnancy.
In the United States, the prevalence of renal angiomyolipoma is 0.3% – 3%.
In Japan, the prevalence of renal angiomyolipoma has been reported to be 0/1%-0/2%
Relationship between tumor size and clinical symptoms.
Doctors say that when the diameter of the tumor is less than four centimeters, it will be asymptomatic in 77% of cases and the affected person will not have any specific clinical manifestations.
If the size of the tumor is more than four centimeters, it will be symptomatic in 82% of cases
The size and diameter of renal angiomyolipoma tumor are significantly associated with its clinical signs.
The larger the tumor, the more likely it is that renal angiomyolipoma will be symptomatic.
Clinical manifestations and symptoms in renal angiomyolipoma
If the renal angiomyolipoma tumor is not asymptomatic, the main and most common clinical presentation will be due to the presence of the tumor, intra-tumor hemorrhage, or bleeding in the space behind the intestines (retroperitoneal hemorrhage).
Symptoms of renal angiomyolipoma tumor:
- Nausea and vomiting (the cause of these symptoms is pressure from the tumor growing on the stomach and the beginning of the small intestine)
- Side pains in bilateral cases
- The presence of a throbbing mass
- Urine in the blood or hematuria
- Newly created hypertension
- Bleeding inside the tumor or behind the intestines:
In chronic bleeding, the patient suffers from anemia, and if the bleeding volume is large and the bleeding time is long, the patient will experience shock symptoms, this will be more common in patients with tuberculosis.
In cases where the angiomyolipoma tumor of the kidney is a single form, the possibility of spontaneous bleeding inside the tumor and the occurrence of shock is also high.
Doctors have reported in several cases that renal angiomyolipoma tumor has spread to the lymph nodes around the kidney and renal vein.
If a child has angiomyolipoma, he or she should be screened for tuberculosis. Usually, these children do not have problems until they are about 50 years old.
Could renal angiomyolipoma be malignant?
There is a rare type of this tumor called angiomyolipoma epithelioid that has a high potential for malignancy.
People with renal angiomyolipoma tumors should be followed up, even if the pathology report is benign.
How to diagnose
Tumor aspiration with a special needle (FNA) and pathological study on a sample obtained under a microscope is very important in tumor diagnosis (plays a key role in definitive diagnosis)
Ultrasound also shows renal angiomyolipoma as a circular mass with a well-defined margin.
Ultrasound, CT scan, and MRI may also be helpful, but the resolution and validity of the images obtained will depend greatly on the fat content of the tumor.
How is renal angiomyolipoma treated?
Most patients with angiomyolipoma will not need kidney treatment. They should only be followed up by imaging once a year or twice a year to check for tumor growth and the enlarged tumor does not cause obstruction in the urinary tract or kidney tissue.
Small tumors do not need treatment and that follow-up will be sufficient. But, in large tumors, kidney resection or nephrectomy may sometimes be necessary. However, controlled embolization and occlusion of an artery that supplies blood to the tumor, or in some cryotherapy cases, may be effective in small tumor sizes.
Small tumors will not need a nephrectomy because the nature of an angiomyolipoma tumor is to grow very slowly.
Surgery is necessary in the following cases:
- In tumors whose first manifestation was bleeding
- Tumors that bleed frequently
- The type of epithelioid we mentioned has a high potential for malignancy.