Ganglion Cyst

Basics

  • Ganglion cysts are common benign tumors that are not related to nerve tissue (as implied incorrectly by the name).
  • Can be located anywhere throughout the body but usually adjacent to or within joints and tendons, with the most common locations being the wrist, foot, and ankle
  • Not a true cyst because microscopic examination does not show an epithelial lining
  • Most are asymptomatic except for mass effect. Local nerve compression can result in pain, neuropathy, or activity limitation.
  • Synonyms: synovial cyst; myxoid cyst; Gideon disease; Bible bump

Epidemiology

  • Can affect all age groups; unusual in children
  • Most common in ages 20 to 40 years and 3 times as common in women
  • Common in dorsal wrist, radial wrist, and dorsum of the distal interphalangeal (DIP) joint (referred to as a mucous cyst)
  • Mucous cysts are usually seen in older patients.
  • 60–70% of hand and wrist ganglion cysts are on the dorsal wrist; 15–20% are on the volar wrist.

Prevalence

  • Prevalence of wrist ganglia in patients presenting with wrist pain is as high as 19%.
  • Prevalence of ganglia in patients with a palpable mass in the wrist is as high as 27%.
  • Reported prevalence in ankles is 5.6%.

Etiology and Pathophysiology

Pathogenesis is unclear. Cysts are filled with mucin and communicate with the adjacent joint space, tendon, and/or tendon sheath via a stalk. Several theories about their origin include:

  • Herniation of synovial lining creates a one-way valve. Although this is supported by dye studies, the lack of a synovial (epithelial) lining in the cyst wall makes this less likely.
  • Mucoid degeneration of connective tissue results in formation of hyaluronic acid, leading to cystic space formation. Studies haven’t confirmed this hypothesis.
  • Joint stress leads to a tear in the joint capsule or tendon sheath allowing synovial fluid to leak into surrounding tissues. Local irritation leads to production of fluid and a pseudocapsule forms (explaining the lack of an epithelial lining).
  • Recurrent stress may stimulate mucin production by nearby mesenchymal cells (seen on electron microscopy) resulting in cyst formation (1).

Genetics
No specific genetic links have been found.

Risk Factors

  • Female > male
  • Osteoarthritis for mucoid cysts
  • Joint trauma (possible but not proven)

Commonly Associated Conditions

Mucous cysts are usually associated with osteoarthritis at the DIP joint.

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