Why Does It Occur?
Mucous Cysts belong to a general group of cysts called Ganglion Cysts and are most commonly associated with osteoarthritis and a bone spur. Some theorize that it is caused by a one-way valve mechanism whereby the normal fluid from the joint is able to be expressed out but not back in, thereby leading to a collection of gelatinous fluid (or mucin) outside of the joint. Others theorize that the bone spur might cause local irritation of the tissues around the joint causing the cells to produce mucin. Trauma can also play a role in their development.
Mucous Cysts appear as bumps near the joint closest to the nail that can fluctuate in size. Because the skin can get very thin with large cysts, the cyst may burst or discharge mucin. If this happens, it is possible that an infection can occur since the skin acts as the normal barrier against infections.
Mucous Cysts can cause significant pain. However, because they are most often associated with arthritis, it may not be obvious if the pain is due to the mass effect of the cyst or because of the arthritis.
If the Mucous Cyst is large enough to press on the germinal matrix (the area of the finger that is responsible for making the nail), deformities of the nail can be seen, which can look like ridges or dents.
While some doctors recommend aspirating the cyst and/or injecting steroids into the area, Dr. Lee does not recommend this as these procedures typically have a high recurrence rate and significantly increases the risk of infection. In general, we recommend observing the cyst as long as possible unless one of the below indications occur.
Dr. Steven Lee recommends urgent surgery in the presence of an infection. Surgery otherwise depends on patient selected reasons such as intolerable pain, nail deformities, or a cyst that has become large enough so that the skin has become translucent (easy to see through). The patient can also opt for surgery for cosmetic reasons as well.
The surgery is relatively quick, can be performed with either general or local/regional anesthesia with sedation, and is typically performed as an outpatient. The purpose of the surgery is to remove the entire cyst down to it's root. If there is a bone spur (which there usually is), this is removed at the same time to help decrease cyst recurrence.
If the rest of the joint is deteriorated because of arthritis, the decision of whether or not to address this at the same surgery has to be made. Addressing significant joint destruction from arthritis is usually done by performing a fusion. The only time this would be appropriate is if the pain was severe enough that the patient wanted to try to get rid of the pain at the expense of sacrificing joint motion.
Although very rare, if the skin has become so thin from the cyst, it is possible that the skin may require a local skin graft to cover the site.
A light dressing and usually a small splint will be placed over the site depending on how extensive the Mucous Cyst was and whether or not a fusion was performed. Because the skin overlying this area can be very thin and tenuous, it is important to keep the dressing clean dry. This includes avoiding sweating as much as possible. Sutures will be removed at 1-2 weeks. The splint may be continued or another 4-6 weeks if a fusion was performed. Otherwise, hand/physical therapy and movement of the finger can be resumed as soon as the incision appears to have completely healed.
Learn more about post-operative care.
*It is important to note that all of the information above is not specific to anyone and is subject to change based on many different factors including but not limited to individual patient, diagnosis, and treatment specific variables. It is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopedic advice or assistance should consult Dr. Steven Lee or an orthopedic specialist of your choice.
*Dr. Steven Lee is a board certified orthopedic surgeon and is double fellowship trained in the areas of Hand and Upper Extremity Surgery, and Sports Medicine. He has offices in New York City, Scarsdale, and Westbury Long Island.