Approach
Ganglion cysts are usually diagnosed clinically without the need for further laboratory or imaging studies unless other pathological processes are suspected.
Historical factors
Cysts commonly present as cosmetic concerns; however, presenting symptoms may include wrist aching (with/without activity), paresthesia, weakness and coolness of the hand/fingers. There may be complaints of the mass increasing in size after activity of the involved extremity, and returning to baseline after rest. They may develop very rapidly: for example, overnight, or over long periods of time.
A history of trauma (vague wrist pain after trauma can suggest scapholunate instability) may be revealed, although cysts usually have an insidious, atraumatic onset.
Physical exam
Volar cysts are usually located between the flexor carpi radialis tendon and the radial artery. Dorsal cysts usually overlie the scapholunate interval, but may arise from a number of sites over the dorsal aspect of the wrist.
Ganglia usually appear as well circumscribed, subcutaneous, smooth masses (typically 1-4 cm in diameter). They are freely mobile structures that are not attached to underlying soft tissue and do not move with finger flexion or extension. Transillumination with a penlight often reveals a reddish glow.
[Figure caption and citation for the preceding image starts]: Transillumination of ganglion cyst using pentorchBotte MJ et al. Musculoskeletal Key. Available at: https://musculoskeletalkey.com/ganglion-excision; used with permission; cited from Green DP et al. Green’s Operative Hand Surgery. 4th ed. New York: Churchill-Livingston, 1999: 2171-83 [Citation ends].
Smaller ganglion or occult ganglion may not be palpable; however, wrist flexion may induce pain.
There is usually no pain on palpation of the mass, but, if large enough, the mass may compress underlying neurologic or vascular structures leading to secondary examination findings. Such neurologic signs may include:[14][15]
numbness in ring and small fingers (due to compression of the ulnar nerve)
numbness over dorsoradial hand (due to compression of the superficial branch of the radial nerve)
numbness in the palm (due to compression of the palmar cutaneous branch of the median nerve)
numbness in the thumb, index, or long finger (due to compression of the median nerve).
Vascular compression typically presents as pain in the radial or ulnar side of the hand depending on the location of the ganglia (radial or ulnar, respectively). The fingers may feel cool, appear pale or blue, and demonstrate sluggish capillary refill if circulation is inadequate to perfuse the hand.
Laboratory tests
Typically, laboratory tests are unremarkable and are only required if there are suspicions of infection. White cell count, erythrocyte sedimentation rate, and C-reactive protein may be elevated in infection.
Imaging
Radiography does not usually yield information that will alter care plans of patients with ganglion cysts, therefore imaging is not typically indicated unless the cause of the mass is doubted.[16]
When the probability of other wrist pathology remains high, ultrasound or magnetic resonance imaging (MRI) may be performed. With regards to ganglion cysts, ultrasound and MRI can help confirm cyst size, physical characteristics, relationship to radial artery, and ligamentous injury.[17][18] There is no difference in ganglion cyst detection rate between ultrasound and MRI.[19][20]
Occult ganglia can be visualized by MRI with a sensitivity of 83%, specificity of 50%, positive predictive value of 94%, and accuracy of 80%.[21]
Aspiration
Dorsal ganglia may be aspirated for diagnostic (and potentially curative) purposes. Aspiration of the volar ganglia is not recommended due to the potential risk of injury to the radial artery.[22]
Care must be taken with aspiration as the cyst is in direct communication with the wrist joint and septic arthritis is a rare complication. Aspiration technique involves sterile preparation, introduction of a large-bore needle (e.g., 18 gauge) into the cyst and removal of cyst contents. A clear, jelly-like, viscous, mucin is diagnostic of a ganglion cyst.
If there are any concerns regarding infection or inflammatory arthropathy, the fluid obtained should be sent for microscopic exam for white blood cells and crystals.
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