GANGLION CYST
Ganglion cysts are commonly encountered in
the general population. They are fluid-filled cavities that occur most commonly
on the dorsal aspect of the hands. They are believed to be derived from the
synovial lining of various tendons. They typically manifest as asymptomatic,
soft, rubbery nodules below the skin.
Clinical Findings: Ganglion
cysts are common benign growths that occur on the distal upper extremity in
most cases; they are almost always located on the dorsal aspect of the hand or
wrist. Ganglion cysts are almost always solitary, but some patients present
with more than one, and occasionally the individual ganglion cysts coalesce
into one large area. Most are relatively small, 1 cm in diameter, but some can
get very large (2-3 cm). The overlying epidermis is normal, and the cyst is
located in the subcutaneous space below the adipose tissue. They are smooth,
dome-shaped, fluid-filled cysts that are slightly compressible. The cyst is a
direct extension of the synovial lining of the tendon. The cysts form by
various mechanisms and fill with synovial fluid. This fluid is critical in the
normal lubrication of the tendon space to decrease friction and allow the
tendon to easily slide back and forth within its synovial covering. These cysts
can occur at any age, but they are much more common in the younger population
and often manifest in the third or fourth decade of life. Women are much more
likely than men to develop these
cysts.
Most cysts are asymptomatic, but they can cause discomfort and pain if
they become large enough to press on underlying structures. Rarely, the cyst
compresses an underlying nerve, resulting in symptoms of numbness or muscle
weakness. The differential diagnosis is limited, and most often the diagnosis
is made clinically. Occasionally, a biopsy is required to differentiate ganglion
cysts from giant cell tumors of the tendon sheath. Giant cell tumors of the
tendon sheath are much more likely to be firm in nature. Ganglion cysts have no
malignant degeneration potential. In difficult cases, an ultrasound examination
can be performed; it is highly sensitive in detecting these fluid-filled cysts.
Pathogenesis: Ganglion cysts are believed to be caused by
an outgrowth of the underlying synovial lining of the tendon sheath. Trauma is
likely the leading culprit in initiating the formation of these cysts. Patients
with osteoarthritis are also at increased risk for development of ganglion
cysts, most likely because of the mechanical trauma that the synovial lining
repetitively undergoes when it rubs against osteoarthritic bone.
Histology: Ganglion cysts are not true cysts in that they
do not have a well-formed epithelial lining that surrounds the entire cystic
cavity. The lining is a loose collection
of fibrous connective tissue composed mostly of collagen. The cyst lining is
multilobulated in most cases and typically has no connection to the underlying
joint capsule or tendon sheath. The contents of the cyst are made of
mucopolysaccharides.
Treatment: No therapy is required for small, asymptomatic
ganglion cysts. If a patient desires removal or if the cyst is causing symptoms,
especially weakness and numbness, therapy is needed. Needle aspiration is often used as a first-line treatment option; a
pressure bandage is applied to try to keep the cyst from reexpanding. After the
aspiration, intralesional injection of triamcinolone is used to try to scar the
lining of the cyst. This has shown excellent results. If aspiration and
injection are not successful, surgical excision is necessary. It is important
to have a hand surgeon evaluate and treat these cysts because of their proximity
to multiple vital nerve and tendon
structures.
