Symptoms and causes

What is it?

A renal cyst is a fluid-filled sac, typically located on the outside edge of the kidney. In contrast to a kidney tumour, a renal cyst is an innocent, benign (i.e. non-harmful) condition.

Sometimes several cysts may develop in the same kidney. If there are a lot of these cysts on both kidneys, we refer to ‘polycystic kidneys’. Only in this instance is there an inherited disorder. In the case of polycystic kidneys, special attention must be paid to preventing high blood pressure and obesity. These risk factors and the polycystic kidneys themselves can cause deterioration of the kidney's filter function.


In very rare cases, a renal cyst can cause pain in the upper abdomen.

Diagnosis and treatment

The diagnosis is made with an ultrasound and/or a CT scan of the abdomen.

Sometimes (though rarely) the distinction between a simple benign kidney cyst and kidney cancer is not easy to make via ultrasound imaging or a CT scan. In this case, the cyst is monitored: at regular intervals (e.g. after six or twelve months), another scan is performed to check whether the cyst has increased in volume. A kidney biopsy may be performed to determine whether it is a simple cyst or kidney cancer.

A renal cyst is only treated in exceptional cases through a puncture or via laparoscopic removal.

Treatment centres and specialisations

Urology Centre

Latest publication date: 25/01/2021
Supervising author: Dr Ameye Filip