A reader recently contacted me concerning cysts on his kidney and I thought that it may be appropriate to review the topic today.
What are cysts and are they dangerous?
Cysts in the kidneys are collections of fluid. In rare cases, cysts may be a manifestation of other diseases such as polycystic kidney disease in which there are many cysts along with kidney damage. Simple cysts in the kidney, which are more common than one would think, are not dangerous, non-cancerous and don’t often cause symptoms. We will discuss simple cysts. To answer the most commonly asked question patients usually have – it is not entirely clear what causes these cysts. They seem to be more common in men and increase as one gets older.
What are the symptoms of simple cysts?
These cysts are often asymptomatic and are commonly discovered during imaging for other conditions. Large cysts may cause a dull back or tummy pain and rarely, a cyst may become infected, causing pain and fever. A large cyst may obstruct the flow of urine, causing the kidney to swell and may lead to kidney damage. Simple cysts which are asymptomatic do not need treatment.
When should I be worried?
A number of imaging tests can be used to look at the kidneys including CT scan, ultrasound and MRI. Although an ultrasound usually suffices especially for simple cysts, the gold standard test is a CT scan using a dye which is injected in the veins. The cysts are graded according to risk of cancer by a system called the Bosniak (pronounced Bos -nee-ack) system. A simple cyst or Type 1 is crisp and thin walled – there are no blood vessels or calcium in the wall. This progresses all the way to Type 4 cysts which have thick walls and parts which are fleshy. Types 3 and 4 cysts have a high risk of cancer and should be removed. A qualified radiologist can look at your imaging and tell you what type of cyst you have.
If you have multiple cysts in both kidneys and have high blood pressure along with poor kidney function on your blood tests you should seek the opinion of a qualified physician.
How are cysts treated?
Simple cysts require no treatment or follow up unless symptomatic. Other lower grade cysts require periodic scans to make sure all is well.
If your CT scan shows that the cyst wall is thick, has calcium and shows that bits of the cyst appear fleshy and solid, then you likely have a higher grade cyst (Type 3 or 4) and your urologist may recommend that you remove all or part of that kidney given the risk of cancer.
For simple cysts which are causing symptoms, a number of treatments exist, ranging from simply removing the fluid with a needle to removing the cyst surgically. In the first case, the procedure is done under local anaesthetic and the doctor uses an ultrasound machine to see the cyst, following which, a small needle is used to remove the fluid. The urologist may inject the cyst with chemicals to prevent it from coming back. This is a day procedure with no hospital stay.
In the case of surgery this is most often done through laparoscopic surgery or “keyhole” surgery through a few small cuts. Limited resources may mean your doctor in rare cases has to make a big cut to remove the cyst.
If you have an ultrasound and you are concerned about cysts I urge you to consult a qualified medical practitioner who can look at the tests further and refer you to a urologist as necessary.
Satyendra Persaud MBBS DM (Urol) FCCS
Department of Urology, San Fernando General Hospital, Trinidad and Tobago
