What Are Kidney Cysts in Children?

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Kidney cysts are round, fluid-filled pouches that develop in the kidneys. In most cases, cysts are small and asymptomatic, and no treatment is needed. Simple kidney cysts are usually discovered during an ultrasound for a different condition.

However, these types of cysts are uncommon in children, so a cyst could be an indication of something more serious. Even if a cyst is not causing symptoms, it is important to evaluate and monitor kidney cysts in children.

Types of Kidney Cysts

Simple Kidney Cysts

Simple kidney cysts are small, usually less than 1 inch in diameter, and they don’t usually cause any symptoms. They are common in older people, but rare in children. Their cause is unknown, and they usually don’t need any treatment. Occasionally, a simple cyst can be large enough to affect function. For example, if a cyst is located close to the ureter opening, it could obstruct urine from flowing from the kidney to the bladder. This can cause a urinary tract infection (UTI) or kidney stones. In rare cases, a simple cyst can also become infected or burst.

Complex Kidney Cysts

Complex kidney cysts are cysts that have more than one fluid pocket. Instead of one fluid-filled pouch, complex cysts have multiple pouches of fluid, like a bunch of grapes. Like simple cysts, these are usually asymptomatic and don’t need treatment. However, a complex cyst indicates a higher risk of cancer than a simple cyst.

This type of cyst should be monitored to make sure it’s not growing larger over time. Like simple cysts, it’s possible — but unlikely — for complex cysts to become infected or burst.

Multicystic Dysplastic Kidney

Multicystic dysplastic kidney is a condition where one kidney didn’t form correctly during fetal development. Although it can be genetic, it usually occurs randomly. In multicystic dysplastic kidney, or MCDK, one kidney is formed of cysts and scar tissue instead of functioning structures. However, typically the other kidney is normal, so this condition causes no symptoms and requires no treatment. Usually, the non-functioning kidney will regress and disappear over time. The other kidney will perform all renal functions for the body.

Polycystic Kidney Disease

Polycystic kidney disease, or PKD, is a serious genetic disease that causes cysts to form in the kidneys. There are two types: autosomal dominant PKD and autosomal recessive PKD.

Autosomal recessive PKD is very rare, occurring about 1 in every 200,000 births. However, this type is more likely to cause symptoms during childhood. It causes multiple cysts to form in both kidneys and in the liver, and it’s usually diagnosed by fetal ultrasound, before the baby is born. It causes progressive kidney failure as both kidneys’ functioning tissue is gradually replaced by cysts. Symptoms could include high blood pressure, swollen belly, recurring UTIs, and back or side pain.

Autosomal dominant PKD causes large kidneys with multiple cysts. Cysts can also occur in the liver. Although this condition is also genetic, symptoms don’t usually develop until the person is between 30 and 50 years old. It’s rare to diagnose this condition in children, since it’s usually asymptomatic until later in life.

Diagnosis and Testing

Kidney cysts can be detected from imaging tests such as:

Asymptomatic kidney cysts are often found during a scan for another unrelated condition.

Treatment of Cystic Kidneys

Kidney cysts that are not causing symptoms do not require any treatment. If the location or size of the cyst causes it to block the ureters or otherwise affect kidney function, then it can be punctured and drained to reduce the size. This procedure, called sclerotherapy, can be done with local anesthesia and does not usually require an overnight hospital stay. In rare cases, a large kidney cyst may need to be surgically removed.

If a cyst becomes infected, it is usually treated with antibiotics. An infected cyst that does not respond to antibiotics may need to be removed or drained.

Your child’s pediatric nephrologist and/or urologist will work together to decide whether to remove a kidney cyst. Complex cysts or large simple cysts may need to be monitored to make sure they are not growing over time.

Children with polycystic kidney disease may need kidney dialysis or a kidney transplant in childhood.

If your child has a cystic disorder of the kidneys, talk to your pediatric nephrologist to create a long-term treatment plan.

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Cooperman Barnabas Medical Center
94 Old Short Hills Road
Livingston, NJ 07039
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Children's Hospital of New Jersey at Newark Beth Israel Medical Center
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Nephrology – Pediatric Treatment & Care

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