Mucoceles of the sinuses
There is quite a bit of confusion about mucous retention cysts (found on CT scan) and mucoceles, which are much less common and treated very differently.
In my practice, this causes a fair amount of un-necessary confusion, and, frankly unnecessary angst, since most are mucous cysts and require no intervention in the vast majority of cases.
Lets start with mucoceles, which do require some intervention in most cases. I’ll add a couple of visuals to help illustrate these differences.
Mucoceles of the sinuses can cause chronic bacterial infections of the sinuses or chronic sinusitis. Mucoceles almost always require surgery to correct them. Mucoceles are much less common than chronic sinusitis with polyps or chronic sinusitis without polyps. Mucoceles are so distinct from the chronic sinusitis with or without polyps that they deserve special attention.
Mucoceles are fluid filled sacs that slowly fill up with mucus and then expand slowly– pushing, compressing, eroding bone and moving structures around them. These mucoceles may expand and push into the eye socket (the orbit) or push into the brain or nose. If a mucocele sac expands into the orbit, it can push the eye out and cause a bulging eye, double vision, or change in vision. If the mucocele pushes into the brain it may not cause many symptoms, unless it gets infected. If a mucocele next to the brain or eye gets infected, there can be a sudden and serious infection of the eye or brain. So patients that come to the doctors with a mucocele usually have symptoms from the mucocele already, and if they don’t, they are at risk of developing a serious complication. So mucoceles usually require surgery. Once in a while, they are observed or followed to see if they will cause problems.
Mucoceles versus mucus retention cysts
Now there is a terminology problem around mucoceles. Some doctors call “cysts” in the sinuses “mucoceles”, when in fact they are just cysts. So, as a patient, it is important to know the difference between a “mucus retention cyst” and a mucocele. A mucus retention cyst is just a cyst along the sinus lining. It’s a fluid filled sac, yes, but a retention cyst does not expand and push into the eye socket, brain, or nose and it doesn’t cause problems in the vast majority of cases. So a cyst is very different than a mucocele.
Notably, mucus retention cysts in the sinuses are very, very common. In fact about 30-40% of people with absolutely no complaints of sinus problems will have cysts of the sinuses when they have a CT scan performed. Most retention cysts of the sinuses spontaneously shrink or don’t change over the long term, based on a study by JH Wang in 2007 . Dr. Wang’s findings suggest that, in the absence of associated complications, “wait and see” may be the appropriate management strategy for these retention cysts. Most every sinus surgeon in the U.S. feels that way too.
How common are mucus retention cysts? Mucus retention cysts are very common. For instance, patients who get a CT scan of there eye for an eye problem will have their sinuses show up on the CT scan, and 30-40% of them have sinus cysts. Well, you may wonder, what does it mean to have a retention cyst? Does anything need to be done for a cyst? Do they cause problems? Most retention cysts of the sinuses spontaneously shrink or don’t change over the long term, based on a study by JH Wang in 2007) . These findings suggest that, in the absence of associated complications, “wait and see” may be the appropriate management strategy for these retention cysts. That is how the vast majority of American surgeons treat these cysts. In fact, wait and see really is usually translated to the patients as “nothing needs to be done for this” or “don’t worry about this, it’s normal to have cysts” or “it’s very unlikely that this cyst will ever cause you problems”, or “nothing further needs to be done, and a follow up CT scan is or examination is not needed”. Doctors are usually reluctant to say a cyst (or a few cysts) “will never cause you problems”. Occasionally a sinus cyst will fill with fluid and then fall into the nose and cause a blockage, but this is very rare. If a cyst did get large enough to cause problems, there would be some symptom, so most doctors say “you don’t need to come see me again unless your symptoms change dramatically”.
But there are always exceptions.
Occasionally, these cysts are mis-named as “mucoceles” by a radiologist. The doctor who ordered the test gets a type-written report that erroneously labels the cysts as a “mucocele”. The doctor who ordered the test may never actually see the films (so can’t see its just cyst—not an expanding mucocele) and the patient is referred to a surgeon. Now most surgeons agree that these cysts are just that, innocent cysts, and can be totally ignored. They are of no clinical consequence in the vast, vast majority of cases. But occasionally there is a surgeon who has had an experience where he or she has removed a cysts and the patient said he or she was better. So, there are some surgeons who remove these “innocent” retention cysts, hoping the patient will get better. Suffice it to say, that the vast, vast majority of these cysts do not need to be removed. If a surgeon says that a “retention cyst” needs to be removed, and you question the explanation yourself, consider getting a second opinion. A second opinion is almost certainly justified.
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Jeffrey E. Terrell, MD
Michigan Sinus Center, Ann Arbor, MI