Benign Kidney Tumors –Cysts, Angiomyolipoma & Oncocytoma

Benign Kidney Tumors.

Any abnormal formation in the body is called a tumor.

Tumors can be benign (noncancerous) and malignant (cancer). Malignant tumors, in contrast to benign, can grow and invade adjacent tissues, and to spread to other distant organs – ie. metastasis. Left untreated, malignant tumors can be fatal. Usually, benign tumors may do not cause symptoms, but because of their size and volume, they can cause pain and / or malfunctioning of the body. The most common benign kidney tumors are cysts. They represent a heterogeneous group of diseases that have a common feature – the presence of a cavity or cavities in the kidney, limited by the epithelium and filled with liquid contents. Cysts can be single (solitary) or multiple, congenital or acquired, seen in children or adults, polycystic and others.

 Benign Kidney Tumors

In this article we describe single (solitary) cysts of the kidney that are the most common and the most “innocent” of all benign kidney tumors. The frequency varies from 0.1% to 4% of children, and amounted to more than 30% in adults over 70 years. They are liquid, rounded or oval collection, enveloped by a thin capsule, with sizes ranging from 2-3 cm to 8-10 cm and even bigger. It is still unknown the exact mechanism of occurrence of cysts, it is believed to be due to a breach in the run-off group of the tubules of the kidney. The contents of the cysts is clear, yellowish liquid whose composition resembles primary urine. Often the cysts are found by chance in some imaging done on another occasion (usually ultrasound) and usually do not cause any symptoms. “Simple” cysts are benign and usually require only periodic monitoring (annually) to determine whether they are increased or not.

The problem with them is that they increase gradually and when they reach the larger sizes (typically over 10 cm), various complaints may occur – dull pain or burden in the side of ribs. Sometimes the cyst can be infected, then the pain at the side of ribs and in the kidney is enhanced, thetemperature rise may appear as blood in urine. Upon reaching a large size, the cyst can “compress” and lead to atrophy of renal parenchyma, lead to disorders in blood supply to the kidneys, which in turn leads to hypertension.Benign Kidney Tumors

Treatment is required only for large cysts of the kidneys that cause discomfort, pain or other disorders of the kidneys – it includes their drainage or other surgery. The most commonly used method for drainage of cysts is their puncture and aspiration through the skin under ultrasound guidance, as often happens to “drain” 200-300 ml and more. In recurrent cysts and those which are not suitable for puncture can resort to surgery where the cyst is “cut”.

Another representative of benign kidney tumors is the angiomyolipoma, which is composed of abnormal blood vessels, muscle and fat cells (from which derives its name – angio – blood vessel, myo- muscle, lipo – fat) and is usually diagnosed by a scanner, which evident adipose tissue in the tumor. Most often the angiomyolipoma does not require treatment other than periodic monitoring to establish its progression, if any. Upon reaching a large size, the angiomyolipoma may become more vulnerable to injuries which lead to internal bleeding. Therefore, although this is a benign tumor, in reaching large size, you may need a surgery to remove it or angiographic manipulation.


Oncocytoma is another rare representative of benign kidney tumors. Unfortunately, through routine imaging methods, it can not be certainly distinguished from carcinoma of the kidney and therefore most often resorting to surgery and the diagnosis is made intraoperatively and / or histologically.Oncocytoma

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