Mucous Cyst

The mucous cyst is a small fluid-filled sac that originates from an interphalangeal joint of a finger or toe.  It usually originates from the DIP joint or end joint of the finger or toe.  It may also occur at the middle joint or PIP joint less commonly.  The cyst is filled with joint fluid and is connected by a small stalk to the joint. a mucous cyst is most commonly associated with osteoarthritis(OA).  Often there is a small spur in the affected joint.  This may reduce a weakening of the capsule or lining of the joint, allowing fluid to escape and formed a mucous cyst.  Typically the mucous cyst will appear slightly to the side of the dorsum or back of the finger/toe.  The capsule in the midportion of the joint is thickened by the extensor tendon.  The joint may also be enlarged secondary to bony spurs from the arthritis.

The cyst may be asymptomatic.  Discomfort may originate from both the cyst and arthritis.  Large cysts are in danger of rupturing due to thinning of the overlying skin.  Since the cyst communicates with the joint, there is a risk of joint infection, which can threaten the finger. we advised against aspirating, poking or draining the cyst due to the risk of infection and since the rate of recurrence is high.  Small asymptomatic cysts are usually observed.  A large cyst which is painful or when the skin is dangerously thin it is usually removed surgically. the surgery is usually performed on an outpatient basis with local standby or twilight anesthesia.  A small incision is made over the cyst and the skin is carefully peeled back, exposing the cyst.  It is traced down to the joint and removed.  If a spur is present, that portion of the joint is opened (arthrotomy) and the spur is removed to reduce the rate of recurrence. a small dressing is applied afterwards.  Risks with this surgery are anesthesia deflated risks, weaning promise or infection, recurrence of the cyst.  Recurrence is approximately 3%.