A mucous cyst is a sac filled with fluid that appears on the finger, above the joint located next to the nail (the distal interphalangeal joint). The cyst can often thin the skin around the nail. The mucous cyst somewhat resembles a balloon on a stick, due to its fluid-filled appearance, and a stalk attached to this that connects the cyst to a joint.
The texture of the cyst is firm and is not easily malleable under the skin. Due to its nature, the cyst is often painful for the patient and is in danger of breaking open, increasing chances of infection.
As a result of the mucous cyst growing so close to the fingernail, the nail can grow with an indentation towards its base or grow irregularly.
Unless a cyst seems to be in danger of rupturing or is causing pain to the patient, it can be left alone without any harm caused to the patient.
Causes of Mucous Cyst
Mucous Cyst is commonly related to osteoarthritis affecting the joint where the cyst develops. Though it is not known exactly how they develop, it is thought that the cysts are formed when connective tissue that connects the tendons in the finger, wears away. When is happens, is it thought that collagen from the degenerated connective tissue is left behind and begins to collect in pools which then form cysts.
Since mucous cyst is most often found in relation to patients suffering from osteoarthritis, the main group of people at risk of this condition is patients between 50 to 70 years old.
It is possible that over time, these cysts will change in size or disappear completely without surgical removal. It is important to note that this type of cyst is not in danger of becoming cancerous or of spreading to any other area.
Symptoms of Mucous Cyst
A mucous cyst is found on the outer most joint of the finger, on the upper side where the nail is. It is usually visible just underneath the skin on the finger, sometimes having caused the skin to thin over the top. The cyst is a small bump, filled with clear fluid, but with a tough outer layer, limiting the movement of it, and feeling quite firm to the touch, unlike a blister or other such complaint.
In most cases of mucous cyst, the issue is not painful and quite often causes little to no problem or dysfunction. If the cyst begins to cause pain or dysfunction for the patient, or has recurrent drainage, or seems to be at risk of rupturing, then a doctor will assess the situation and decide on the treatment needed.
Diagnosis of Mucous Cyst
Despite the low risk for patients with suspected mucous cyst, it is recommended that a clear diagnosis be made by a doctor, to assess the condition and examine for any other underlying or related issues. Diagnosis of mucous cyst is relatively simple for most doctors or hand specialists. A doctor will examine the fingers and discuss the history of the issue with the patient.
Since mucous cyst is most commonly related to the condition of arthritis, if the patient has never been diagnosed with this, a doctor will do a full assessment to determine if the root cause is an arthritic issue or if the cyst is simply an anomaly.
The doctor may also order an X-ray to examine the joint in the case of osteoarthritis to understand the level of joint degeneration. In the case where arthritis has not been previously diagnosed, the X-ray will confirm this also.
Treatment for Mucous Cyst
Often, the appropriate method of treatment for mucous cysts is to observe the cyst over time, paying attention to worsening symptoms or the possibility of it rupturing.
It is important for the patient to resist puncturing the cyst themselves, due to high risk of infection and lack of understanding on how to do this properly. If the cyst is becoming painful or close to rupturing, it is advised to be seen by a doctor who can take the next step in treating the issue.
If the cyst does rupture, it needs medical attention. At the base of the cyst is a stem connected to the joint, and when the cyst ruptures, it leaves a path directly into the joint that exposes it to possibility of deep infection inside the joint. In this case, a doctor will prescribe antibiotics that should be applied directly onto the site of the rupture, and the finger should be wrapped in a dressing. It is likely that a doctor will also prescribe oral antibiotics in addition. If the joint still develops an infection, the next step will be surgery.
Surgical Treatment for Mucous Cyst
If the site of the cyst causes significant pain prior to rupture, there are two main surgical options that can treat the root issue:
The first option is needle puncture, where a needle is used to puncture the cyst and then the cyst is aspirated (where the fluid is drawn out by suction). The problem with this procedure is that the recurrence rate is high, with over 50 percent of cases deemed unsuccessful in the long term.
The second option is to use excision (removal of the cyst), including the removal of its stem or connection to the joint itself. However, if the underlying cause of pain is not the cyst but osteoarthritis, it should be noted that the surgical removal of the cyst and its stem will not eliminate all pain.
In this procedure, the whole cyst, its stem and any bone spurs on the joint are fully removed. In cases where the skin on the finger is closely attached to the cyst, it may be necessary to remove a small portion of skin as well. In this situation, a small skin graft will be added to the spot where the skin is removed. In most cases, this surgical procedure can be performed using only regional anesthesia, numbing just the arm or even just the finger with lidocaine. The surgery can be done in-office and may take only fifteen minutes provided there are no complications.
Both of these procedures present a risk of infection. Also, even with the excision surgery, it is possible to experience a recurrence of a mucous cyst; however the cases of this are rare.
When the surgery is completed and in the cases where a skin graft is needed, a doctor will provide a cast or a splint for up to two weeks.
Once this is removed, there will be exercises given to the patient by a hand therapist in order to restore full movement and will be continued until the pain in the finger is completely gone.
Seeking Treatment for Mucous Cyst
Our goal at OSMI is to provide our patients quality, cutting-edge orthopedic treatments, both surgical and non-surgical. If you or someone you know has a growth on their finger matching the description of a mucous cyst and if you or they are already known to suffer from arthritis, please submit an online appointment request or contact our office at 817-529-1900.