Renal cysts

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Monday, February 3, 2014

A SIMPLE renal cyst is a round smooth, thin-walled pouch or a closed pocket that is usually filled with fluid. It may be solitary or multiple. One or both kidneys may be involved. Simple cysts are the most common type of kidney cyst.

It is not fully understood what causes formation of a renal cyst, but they do not appear to be inherited. There is one theory that suggests that kidney cysts develop when the surface layer of the kidney weakens and forms a pouch Males as well as those aged 50 years old are more commonly affected.

Majority of renal cysts produce no symptoms, they are often incidentally discovered during imaging studies for another condition. However, some renal cysts can cause symptoms such as flank pain, palpable lumps in the abdomen, bloody urine, hypertension, or urinary tract obstruction.


The first imaging test that discovers the cyst is usually an ultrasound. The definitive imaging modality for a renal cyst is a CT scan which is the basis of the Bosniak Classification of Renal Cysts.

This classification is the most useful and widely employed method for characterizing renal cystic lesions and for assessing the likelihood of the presence of a concomitant malignancy within the cyst. It is used as a guide by the urologists for the management of renal cyst. Aside from the Bosniak classification, a CT scan is also used for assessment prior to a contemplated surgical procedure for the cyst.

For Bosniak I and II, these are most likely simple and benign cysts and require no treatment or follow-up. A Bosniak IIF, though may be benign, but due to some findings in the cyst may require repeat imaging to assess stability of size and radiographic characteristics. Bosniak III and IV show cysts that have a higher risk for malignancy (50 percent for Class III and 75-90 percent for Class IV), hence surgery is required.

Simple renal cysts that are symptomatic measuring between 4-6 centimeters, an ultrasound guided aspiration can be done by your urologist. This is done by inserting a long needle into the cyst while being guided by ultrasound, then the contents of the cysts are aspirated. There is a higher chance for the cyst to recur if aspiration is done for cysts more than 6 centimeters.

For simple renal cysts that grow larger than six centimeters and cause symptoms due to compression against adjacent organs or cause urinary tract obstruction, your urologist will perform a laparoscopic unroofing of renal cyst. This procedure is a minimally invasive urologic surgery where a telescope is inserted in the abdomen through one port and two other ports are made for the instruments.

The renal cyst is dissected then punctured and the contents are evacuated. After removal of the cyst contents, the wall of the cyst is excised.

Renal cysts may be small and produce no symptoms or may grow large and cause problems, so once a cyst is discovered in your kidney/s during a routine ultrasound or CT scan, consult your urologist for evaluation of the said cyst.


About the Author: Dr. Latayan is a Diplomate of the Philippine Board of Urology and a Fellow of the Philippine Urological Association and of the Philippine College of Surgeons. He had his training in urology at National Kidney and Transplant Institute. The scope of training included Adult And Pediatric Urology; Endourology, Minimally Invasive And Laparoscopic Urology; Transplant Urology (Donor). Presently, he is an Active Urology Consultant and section head of Urology in the Minimally Invasive Surgery Department of the DMSF Hospital.

He is also an Active Urology Consultant in Metro Davao Medical and Research Center Hospital and Southern Philippines Medical Center.

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Published in the Sun.Star Davao newspaper on February 04, 2014.


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