What is a Renal Cyst and How Is It Treated? | UCLA Health | Brian Shuch, MD

Hello, I'm Dr. Brian Shuck, director of the kidney cancer program at UCLA, and today I'm going to discuss a very common situation that we see in clinical patients who come in with kidney

cyst

s. What is a kidney

cyst

and how is it

treated

? We'll get into that, thank you for your time today. So

what

are kidney cysts? A kidney cyst is basically a pocket of fluid that arises from the kidney, as you can see here the kidney that is shaped like a bean can have a cyst which is just a fluid filled structure in the kidney and how common is a cyst kidney, these are actually very common, we see them weekly, several each week come to my clinic and up to half of people over 50 if their kidneys look like they actually probably have a cyst and many patients can have more than one cyst, so if you have a cyst, welcome to the club, you're probably in the majority now.

Do cysts cause symptoms? 95 percent of kidney cysts are asymptomatic, so if you find out you have a cyst and you say, "Oh, I've been having back pain." The strange movement is probably not the cause of back pain, but occasionally a patient with a really single and large cyst measuring about three inches or more or nine ten centimeters in size may occasionally cause some local symptoms such as flank pain, back pain depends on where the cyst is on the kidney, but if you have a large cyst and pain in your back or side, it could potentially be the cause, but it is rare and more Cysts do not affect kidney function, they do not exceed the

renal

function.

Now why did this happen? It's a genetic thing that patients usually ask about. We know that 95 assists are actually caused by unknown factors. These are things that are probably due to maybe something that has a nephron, the functional unit of the kidney maybe gets included and something explodes and causes a buildup of fluid. We don't really know why most patients have cysts that form and there isn't really any research that is really sponsored or funded in this area because most of these cause no harm now, rarely some individuals may have a genetic form of cystic kidney disease and it is called autosomal dominant polycystic kidney disease and this is because this is found in basically one in a thousand individuals and we suspect this when there are dozens of kidney cysts, when patients have other family members with kidney cysts, there may be liver assistance and patients also lose kidney function, but this is not our topic of discussion today, but we also see it in most.

Assists are not due to a genetic cause and are something that probably occurs only due to sporadic bad luck. Now there are different types of fluid in attendance, so there could be different types of cysts. We have cysts that can range from low density water. filled, we call these simple cysts, we have some that are filled with protein or high-density material. I call it shake and there are others that are full of old blood, maybe there is just old blood that is just there, it is not attached to the bloodstream and these are called hemorrhagic cysts, they actually look very different on the pictures and can be distinguish simple ones from high-density protein or hemorrhagic cysts.

Now there is also something called complex cysts to confuse us even more and sometimes these complex cysts are more than just a pocket of fluid. I tell patients that they have some junk inside and this junk could be thick walls or solid elements and, In principle, the more rubbish, the more worrying it is that we use this classification system that was developed by a famous radiologist, Dr. Bosniak, and it is called Bosnian kidney cyst. grading system and we rate it from one to four and the goal of that is to help us better stratify the risk how complex that garbage is in terms of danger to the patient, the lower the score, the less of a problem it is.

This is now,

what

are some minimally? complex cysts well, these are complex cysts that are considered benign or really minimally complex, something that has slightly thickened walls or maybe a septum, a divider. I would consider it as a divider when you're trying to divide a room, a room separation divider, these are what we would call minimally complex cysts we call them bosniak-2 and these are the ones that don't really need to be followed up now there are some more moderately complex cysts and these they will be the bosniak 2fs and these are the ones that are probably benign they have a 95 chance of being benign, but they are the ones that may have very thick walls or very thick septa or maybe they look bright on the images when we use contrast and sometimes , five percent of these cysts can change.

Now there are also very complex cysts and these very complex sister cysts that are a little more concerning and these are the ones that have very, very thick walls, like bosniak 3, they may have some nodularity in those walls or they may have a solid component in in that bag of water there could be something like a solid enhancing component, we call it four Bosnians, these have a much higher probability of being cancer and these can be 40 to 50 percent, these can be 90 to 95 percent, but Fortunately most of these cystic tumors, even when they are cancers, are generally less aggressive and slower that we can sometimes even observe, so how do we manage these patients well if it is a minimally complex or benign-looking cyst?

We very rarely do it. We need to treat a cyst like this, we usually ignore them and don't do more imaging, but occasionally there are cysts that can grow and simple cyst can infrequently cause symptoms, so occasionally they are very large simple cysts like this one here where Occupy a large portion of the kidney and something like this is potentially considered image-guided drainage or aspiration, so a patient with a 10 centimeter assist would potentially start if they told me I'm in a lot of pain, I would go to a radiologist. They drained some of the fluid, they did, it got better yes it got better.

You might be convinced that maybe it's the cause. Many patients have other causes and by draining the fluid, which we consider a test, we would say, Well, it probably wasn't. The cause is that now we would put a needle in, we would suction out the fluid, the cyst would get smaller and again we say, you know, it got better, but over time a lot of these cysts will build up again, so if the pain got better and then it got worse and you show that the cyst has built up again, then we have options: we can aspirate again, put medication in that cyst to cause sclerosis, maybe scar that cavity so it doesn't build up again, or we can do a quick surgery to actually put Small incisions in the cyst and scalp basically decorticate the lining of that wall so it can no longer build up.

Well, what happens to that liquid if it comes back? Your body can actually reabsorb a large amount of fluid in your abdominal cavity every day. What about these more? complex systems, these are the ones that are moderately complex cysts, well, we look closely at these types of cysts that are more moderately complex, these are the Bosnian 2fs, if the biopsy of these things has a minimal role, it is very difficult to stick a needle and capture a little bit of one of these septum dividers, are because they are not big solid pieces of tumor that you can grab with a needle, they are actually a fluid that can be drained and, understanding that the fluid does not It is very valuable, we rarely do it. any biopsy because you can't get a good portion of tissue so over time we look at them and basically what happens is a simple benign cyst generally most of them are not cancer the benign cysts are not cancer but the complex cyst as we are discussing Now they can represent cancer, these Bosnian 2f cysts that have a five percent chance of cancer, they don't turn into cancer, these complex cysts, Bosnian 2f, basically over time declare air themselves, right when you get to college, you declare your specialty over time. help like this, follow this complex cyst for several years, if I recommend surveillance, I would say there is no change after several years, it is probably benign or I can say well, it got a little bigger, there is more fluid, but it is not more complex, something like this. don't worry about more water in the cyst I'm not worried about the water I'm worried about the complexity if a cyst like this doesn't get more complex it's still considered safe and benign but there are cysts over time they themselves declare that they were Cancers all the time and over time they start to develop this solid component and something like this is probably a cancer, so we're very glad we monitored it because then we can potentially decide if we need to intervene, so again we can't treat a benign cyst.

We do not monitor, they do not become cancer, it is these complexes that over time sometimes declare themselves and that is why we could monitor them to understand what happens, they declare themselves and become a more complex situation and, finally, the cyst very complex, these are the Bosnian three and four that have very thick septa or enhancements or perhaps a solid component, these cysts may represent a cancer that would need further evaluation. We often consider treatment in these types of cysts, however, close monitoring may be considered for some of these three Bosnians. and four kidney lesions because they are often a little less aggressive, we consider them more indolent and over time they don't change as quickly, so this type of management of complex cysts is very complex and many doctors do not understand what the best complex approach is .

Cysts rarely need urgent treatment. If you are concerned, it is often helpful to consult an experienced radiologist at the center. These are radiologists very familiar with their Bosnian classification system. If they take a look, they sometimes upgrade or downgrade support, so rather than rushing to find a cyst where one radiologist says it's complex and needs to be

treated

, you may want to get another opinion and have another expert radiologist look at this. closely because it does matter. Thank you very much for your time and attention. You are welcome. We at UCLA have a very extensive comprehensive kidney program.

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