Kidney Cysts

By:    Published: August 1, 2012

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Nearly 50 percent of people aged 50 and older develop kidney cysts at some point in their life. Kidney cysts are rounded, liquid-filled sacs that develop within the kidneys. They are generally not troublesome and often do not cause any symptoms.

However, in certain cases, the development of kidney cysts may be the result of an underlying medical condition and there may be serious complications associated with them. Your doctor will be able to determine the cause for your kidney cysts and what action needs to be taken, if any, to treat them and their underlying cause.

Definition

There are two different types of kidney cysts: simple and complex.

  • Simple kidney cysts are typically benign and often times are not accompanied by any symptoms. Simple kidney cysts are the most commonly diagnosed type. Generally, simple kidney cysts are discovered accidentally when undergoing testing for another ailment.
  • Complex kidney cysts are cysts that have characteristics that may make them cancerous. They may be linked to a more serious condition or may weaken kidney function.

Characteristics of simple kidney cysts:

  • Thin wall of cyst
  • Round in shape with no irregularities when viewed by ultrasound or CT scan
  • Filled only with fluid
  • No chance of becoming cancerous

Characteristics of complex kidney cysts:

  • Irregular in shape
  • Irregular inside, with walls within the cyst
  • Calcifications visual inside the cyst
  • Solid material within the cyst that receives a blood supply
  • May be cancerous or may become cancerous

Symptoms

Generally, simple kidney cysts do not cause any symptoms. However, if the cyst grows large enough, symptoms may begin to be noticeable. Symptoms of larger cysts include:

  • A dull ache in the back or side
  • Elevated fever
  • Pain in the upper portion of the abdomen

Similar symptoms may be observed when a complex cyst is present. Additionally, complex cysts may produce a variety of symptoms including:

  • Blood in urine
  • Urinary tract infection
  • Headache
  • Frequent urination
  • Pain in the back and/or abdomen
  • High blood pressure

Causes

The cause of simple kidney cysts is not known. However, complex kidney cysts may be the result of another medical condition such as polycystic kidney disease and they could be present at birth. Furthermore, complex cysts could be induced by a parasitic infection such as tapeworm.

Risk Factors

While simple kidney cysts can occur at any age, your risk increases as you get older. The risk for developing complex kidney cysts increases in people who undergo dialysis treatment, which makes them more susceptible to cysts forming.

Diagnostic Tests

Nearly all kidney cysts are discovered upon receiving some type of imaging test. Tests used to diagnose kidney cysts include:

  • Ultrasound
  • CT Scan
  • MRI
  • Blood test to evaluate kidney function

If a kidney cyst is complex it will be evaluated according to a grading system to classify these types of cysts. This classification system is known as Bosniak Classification and determines the potential of the cyst for becoming cancerous. Bosniak categories are numbered I, II, IIF, III and IV; category IV refers to a cyst that is most likely cancerous.

Treatment Options

If you have been diagnosed with a simple kidney cyst and are not currently having symptoms, no treatment is necessary. However, if you begin to have troublesome symptoms, treatment may include:

  • Draining the cyst to remove fluid.
  • Replacing the drained fluid with alcohol to prevent it from reappearing.
  • Surgery to have the cyst removed.

If your kidney cyst is cancerous, it will likely be removed or destroyed. Procedures for removing and destroying cancerous complex cysts include:

  • Cryoablation: extreme cold is used to freeze and destroy the cyst.
  • Radiofrequency Ablation: heat energy is used to destroy the cyst.
  • Partial Nephrectomy: the cancer and surrounding normal tissue id removed.
  • Radical Nephrectomy: the entire kidney needs to be removed.

Complications

Kidney cysts may cause certain complications, which will undoubtedly cause pain in the back and/or side including:

  • Infection within the cyst
  • Bursting of the cyst
  • Obstruction of urine
  • Hydronephrosis, swelling of the kidney

Considerations

It is very likely that you may discover that you have a simple kidney cyst as the result of an imaging test that is performed for another reason. Because simple kidney cysts are common and typically have no symptoms, you may not even realize that you have one. To put your mind at ease, you may want to prepare a list of questions to ask your doctor including:

  • How large is the cyst?
  • Will it grow?
  • Will it damage my kidney?
  • What are my treatment options?
  • Will I need further testing?
  • Will I need to see a specialist?

Kidney cysts are quite common, especially in people over the age of 50. Kidney cysts can be benign with no symptoms at all and may go unnoticed, or they can be complex and potentially troublesome or cancerous. Imaging tests will likely be used to diagnose a kidney cyst. Depending upon the type of kidney cyst, you may not require any type of treatment.

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