Introduction
Mucous cysts are fluid filled lumps which arise over the joints of the finger. They are benign and filled with mucinous (gel-like) fluid which comes from the joint.
These cysts occur commonly near the fingernail and are cause by underlying arthritis in the finger joint.
Mucous most commonly occur in the 50-70yr age group. Females are most commonly affected.
Most cysts are painless and do not require any particular treatment.
Causes
Mucous cysts are related to underlying arthritis or injury / irritation in the joint.
With progressive arthritis, there is degeneration of the soft tissues (capsule) around the joint and the mucinous fluid escapes to form a sac (cyst).
They may also occur as a result of mechanical irritation or trauma to the joints / tendons or ligaments.
Signs and symptoms
Diagnosis is based on patient symptoms and scans. The majority of cysts do not cause symptoms.
Lump
Some cysts may be very small and an obvious lump not visible. The lump may enlarge over time.
Pain
Some cysts may cause pain.
Skin Thinning
The skin over the cyst becomes thinned and shiny.
Fingernail changes
The pressure of the cyst may cause a groove in the fingernail.
Tests
Ultrasound
Ultrasound will demonstrate size and location of cyst.
X-ray
X-ray will show arthritis of the affected joint.
Non-surgical treatment
Mucous cysts are benign, most are pain free and do not require treatment. Treatment is required for cysts that are painful or interfere with activity.
Needle Aspiration
This involves placing a needle in the cyst and draining fluid from it.
Recurrence of the cyst is however common with this procedure as it doesn't eliminate the root cause of the cyst which is in the joint. The risks of needle aspiration also include infection.