Ganglion Cyst

The commonest soft tissue mass of the hand and wrist. It is a mucin filled, thin walled cystic swelling arising from a joint capsule or tendon sheath, containing clear, thick, gelatinous fluid rich in hyaluronic acid. It connects to the joint by a narrow stalk that acts as a one way valve.

• Occurs at any age but most often between 20 and 50 years, and affects women about 3 times more than men.
• Typical sites: dorsal wrist (60 to 70%, from the scapholunate ligament region), volar wrist (15 to 20%, from the radioscaphoid or scaphotrapezial joint, near the radial artery), flexor tendon sheath at the base of the finger (the retinacular or "pearl" cyst, 2 to 3 mm to 1 cm, 10 to 15%), and the distal interphalangeal joint (mucous cyst, with osteoarthritis and often a nail groove deformity). Foot, ankle and knee ganglia also occur.
• The cause is uncertain. Repetitive stress, trauma and joint degeneration are associated, and the cyst arises from mucoid degeneration of connective tissue.
• Up to 40 to 60% of untreated ganglia resolve spontaneously over months to years, and most are benign.

• A smooth, firm to rubbery, round, mobile or fixed swelling, 1 to 3 cm, that may fluctuate in size and often enlarges with activity. Many are painless, and others cause aching, weakness, or pain on wrist extension or loading.
• Transillumination is positive for a simple cystic swelling, though thick contents may block light.
• Volar ganglia may compress the radial artery, median or ulnar nerve (paraesthesia, weakness). Mucous cysts produce nail ridging and can discharge and become infected.
• Occult dorsal ganglia are not visible and cause chronic dorsal wrist pain on loading, with tenderness over the scapholunate interval.
• Differential diagnosis: lipoma, giant cell tumour of the tendon sheath, epidermoid inclusion cyst, rheumatoid nodule, gouty tophus, osteoarthritic osteophyte, carpal boss (a hard fixed bony prominence over the second and third carpometacarpal joints), radial artery aneurysm or pseudoaneurysm (pulsatile, with a bruit), tenosynovitis, Kienbock disease, scapholunate ligament injury, and soft tissue sarcoma (rapidly growing, hard, fixed).
• Complications: pain, restricted movement, nerve compression, nail deformity, infection of a mucous cyst, and recurrence.

• Clinical, with positive transillumination for most dorsal and volar ganglia.
• Ultrasound confirms a cystic structure, its stalk, and its relation to the radial artery (use Doppler before any volar aspiration or surgery), and identifies occult ganglia.
• MRI for occult ganglia, diagnostic doubt, suspected ligament injury, avascular necrosis of the lunate or tumour.
• X-ray of the wrist or finger if osteoarthritis, a carpal boss, bone lesion or fracture is possible.
• Aspiration reveals thick, clear, jelly like fluid, which confirms the diagnosis. Send for histology any mass that is solid, rapidly growing or bloody.

• Observation: reassure the patient that the cyst is benign. Treat only if painful, cosmetically bothersome, restricting function, or compressing a nerve. A period of observation for 6 to 12 months is reasonable.
• Aspiration, with or without injection:
  • Prepare with chlorhexidine 2%, use local anaesthetic (lidocaine 1% 1 to 2 mL), and a large bore needle (16 to 18 gauge) to extract the thick fluid, with firm pressure on the cyst.
  • Recurrence after aspiration alone is 50 to 70%. Adding triamcinolone acetonide 10 to 20 mg injection modestly reduces recurrence, with a risk of skin depigmentation and atrophy.
  • Do not aspirate volar ganglia without Doppler ultrasound confirmation that the radial artery is not adherent or in the path.
  • Rupturing the cyst by striking it with a book or hard object is hazardous and not advised.
• Splinting and rest of the wrist for 1 to 2 weeks after aspiration, then gradual activity.
• Surgical excision for symptomatic ganglia, or recurrence after aspiration:
  • Open excision of the entire cyst, with its stalk and a small cuff of joint capsule, under regional or local anaesthesia with a tourniquet. Recurrence 5 to 15% (volar slightly higher).
  • Arthroscopic excision for dorsal and occult ganglia, with a similar recurrence rate and faster recovery in some series.
  • Mucous cysts at the distal interphalangeal joint: excision with removal of the osteophyte and capsule defect, with recurrence below 10%. Treat discharging or infected cysts with flucloxacillin 500 mg orally 6 hourly for 7 days (clindamycin 300 to 450 mg 8 hourly in penicillin allergy) and urgent excision to prevent septic arthritis.
  • Retinacular cysts at the finger base: aspiration with a needle, or excision. Many rupture on firm pressure.
• Surgical risks: recurrence, scar tenderness, joint stiffness, nerve or artery injury (volar), and reduced grip strength. Splint 1 to 2 weeks, early finger movement.
• Special groups:
  • Children: ganglia are common and resolve spontaneously in most (about 80%), so observe and aspirate only for persistent symptoms.
  • Pregnancy: observe. Aspiration is acceptable if needed.
  • Anticoagulation: aspirate with firm pressure afterwards, or defer.
  • Rheumatoid arthritis and gout: treat the joint disease, because ganglia recur.
• Follow up: review at 2 to 6 weeks after aspiration or surgery, and again at 3 months. Refer to hand surgery for volar or occult ganglia, nerve or vessel compression, recurrence, or a solid or rapidly growing mass.