A mucoid cyst (digital mucous cyst) is a solitary, papular, raised, round-oval, elastic-feeling symmetrical swelling that varies in size from 1 to 15 mm. The cyst contains a viscous, clear fluid. A mucoid cyst is located on the last joint of the finger, often on the skin around the nail bed. The cause is degeneration of the connective tissue of the DIP joint of the finger or toe. The DIP joint is the top joint of the finger or toe. The doctor will often advocate a wait-and-see policy if there are no complaints. The cyst may disappear spontaneously over time. If complaints occur, treatment will follow, such as repeated punctures or surgical excision of the cyst. After treatment, recurrences often occur, i.e. the bump returns. As of 2023, there are no known ways to prevent these cysts. Complications rarely occur. Sometimes the skin over the bump can ulcerate, which can lead to an infection.
- Mucoid cyst: key points
- A hard bump on the back of the fingers or toes
- Occurrence of a mucoid cyst
- Causes of a mucoid cyst
- Risk factors
- Symptoms of a mucoid cyst
- Location: back of finger or toe
- Aspect: subcutaneous, smooth and hard
- Growth and size
- Nail abnormalities
- Pain complaints
- Chronic flood
- Functional limitation
- Consult your GP
- Examination and diagnosis
- Treatment of a mucoid cyst
- Wait and see policy
- Non-surgical treatments
- Surgical treatments
Mucoid cyst: key points
- A mucoid cyst is a cyst that originates from the end joint of the finger.
- It’s a benign ganglion.
- A mucoid cyst is a fluid-filled thickening of the tendon sheath.
- A mucoid cyst can be removed by surgery.
A hard bump on the back of the fingers or toes
A mucoid cyst is a skin-colored solitary tumor that often occurs on the back of the fingers or toes. It is a hard bump on the back of the fingers or toes. The nodule is filled with a viscous, clear fluid.
Occurrence of a mucoid cyst
These skin abnormalities are mainly observed in people over 40 years of age. It is more common in women than men, with the ratio being approximately 7:3. Of all cysts located in the hand, approximately 15-20% are mucoid cysts.
Causes of a mucoid cyst
The cause of this condition has not yet been clarified in 2023, but must be sought in degeneration of connective tissue of the distal interphalangeal joint (in Latin: articulatio interphalangea distalis, abbreviated as DIP) of the finger or toe. The DIP joint is the joint between the penultimate and the end phalanx.
Being overweight is one risk factor / Source: Istock.com/VladimirFLoyd
The following risk factors are known:
- Osteoarthritis or other degenerative joint disease: This is because joint inflammation can cause synovial fluid or synovial fluid, a clear fluid found in joint cavities, to leak from the joint, forming a cyst.
- Overproduction of a substance called mucin in the connective tissue cells or fibroblasts: This is not due to a degenerative joint disease and does not usually arise from another underlying condition.
- Injury: Injured a finger or toe in the past: This can be especially true in younger people.
- Myxoid cysts are more common in middle-aged and elderly people, as well as in women. This is because people in these groups are more likely to develop osteoarthritis.
- Obesity: being significantly overweight puts more pressure on the joints.
- Repeated use or overloading of the joints: this can damage the joints and increase the risk of osteoarthritis.
- Genetic factors: Having a family history of osteoarthritis means a person is more likely to develop it themselves.
A mucoid cyst on a toe / Source: Jmarchn, Wikimedia Commons (CC BY-SA-3.0)
Symptoms of a mucoid cyst
Location: back of finger or toe
A mucoid cyst is a skin-colored solitary tumor that often occurs on the back of a finger or toe. It occurs most frequently on the index and middle fingers of the dominant hand. Usually there is only one cyst, but sometimes multiple cysts develop on the same finger or toe. In some people, multiple mucoid cysts appear on multiple fingers.
Aspect: subcutaneous, smooth and hard
It is a smooth and hard bump that lies just under the skin and is usually painless. The tumor can be a few millimeters to a centimeter in size and is located on the last joint of the finger (DIP joint) and on the skin around the nail bed or within a centimeter away from it.
Growth and size
The cyst grows slowly over several months. The size of a mucoid cyst varies from a few millimeters to a centimeter.
Mucoid cysts are skin-colored, translucent, or reddish-blue in color. Furthermore, the cysts often look ugly.
As a result of pressure on the nail matrix, a groove or dent can develop in the nail, in line with the cyst. Sometimes it can cause nail loss. Myxoid cysts that grow under the nail are rare. These can be painful, depending on how much the cyst changes the nail shape.
Sometimes pain occurs as a result of local pressure, or it is accompanied by joint pain.
Chronic flow of jelly from the cyst may also occur.
Occasionally the cyst or underlying joint becomes infected.
With a large cyst, functional limitation may occur. There may be a limited range of motion of the toe or finger joint as a result of the cyst.
General practitioner examines a foot / Source: Alexander Raths/Shutterstock.com
Consult your GP
Mucoid cysts often shrink or disappear on their own. But even if they do not involute, most cases are not painful and many people can live with it. Consult your doctor if the cyst:
- is perceived as cosmetically disturbing
- causes pain or discomfort
- interferes with daily activities and tasks
- is infected or if the tide comes out
Examination and diagnosis
The doctor will examine the appearance and location of the mucoid cyst and ask about other symptoms you are experiencing or have noticed. Besides a physical examination, no additional examination is usually necessary. In some cases, an X-ray can be taken, which often shows abnormalities caused by degeneration of the joint. The doctor will then discuss the available treatment options and the benefits and risks of each option.
Treatment of a mucoid cyst
Wait and see policy
Since the cyst can disappear spontaneously, the doctor often adopts a wait-and-see policy if there are no further complaints. Otherwise, the syrupy fluid can be removed by puncture and/or drainage. Surgical intervention under local anesthesia is considered when there is pain, recurring infections or persistent leakage of fluid from the cyst.
Non-surgical treatment methods include:
- burn the cyst using infrared heat, laser or light therapy
- using liquid nitrogen or cryotherapy to freeze the cyst, which can reduce its size but does not prevent the fluid from building up again
- puncturing the cyst by making a puncture, although this may have to be done several times
- injecting the cyst with steroids or chemicals to reduce the fluid volume
Relapses occur frequently after treatment.
Surgical treatments for permanent removal have a much higher success rate, approximately around 95%. Surgical surgery is normally performed under local anesthesia and the procedure usually takes about 30 minutes. During the procedure, a surgeon cuts away the cyst, along with any connective tissue and any bone spurs (osteophytes), after which the wound is covered with a skin flap. This can be skin from a skin graft or the skin from above the cyst. After surgery, you will need to wear a splint and do daily exercises, usually for at least 2 weeks. You may experience some tenderness or pain during the recovery process. Any nail abnormalities will usually disappear on their own after the operation.
Never attempt to remove or drain a cyst at home. Leave this to a doctor. There are indications that applying a firm compress to the cyst every day for weeks can provide relief and shrink the cyst. However, there is no evidence that other home remedies, such as soaking or massaging fingers and toes, are effective.
In 2023, there is no method to prevent the occurrence of a digital mucous cyst.
Complications due to a mucoid cyst are rare. Occasionally, the skin over the lesion can ulcerate, which can lead to an infection. As the bump gets bigger, the tumor can be painful to the touch and pose a cosmetic problem.
More aggressive surgical treatment to remove underlying osteophytes from the joint slightly increases the risk of surgical complications such as joint stiffness and loss of motion.
A mucoid cyst is a benign condition. Complete surgical excision is considered the treatment of choice.
The prognosis after complete removal of the lesion is excellent, although recurrences often occur. This means that the cyst returns.
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