Digital mucous cyst

• digital mucous cysts are benign ganglion cysts of the digits
  • the lesions are typically located at the distal interphalangeal (DIP) joints or in the proximal nail fold
  • degenerative mucoid cysts present as cystic 'boggy swellings' proximal to the base of the fingernail on joints affected by nodular OA
    • represent a form of ganglion cyst attached to the joint capsule by a stalk that allows fluid to move into the cyst from the joint
    • may be cosmetically unattractive but rarely interfere with hand function and are often asymptomatic unless knocked
      
      
  • gnerally occur on the hands - although these lesions have been noted to occur on the toes
    • these cutaneous lesions have also been referred to as synovial cysts, periarticular fibromas, myxoid cysts, ganglion cysts, mucinous pseudocysts, and mucous cysts
    • generally the cysts are asymptomatic
      • may appear suddenly or develop over a period of months
      • offten, osteoarthritis of the small joints is noted at the site of cyst emergence
      • occasionally intermittent spontaneous discharge of cyst contents can occur, and, in a significant fraction of cases, cysts may disappear spontaneously
      • antecedent trauma has been documented in a small minority of cases
      • as cysts enlarge, pain is an increasingly common complaint. Patients are also likely to complain about the appearance of larger cysts and may occasionally report interference with function. The many different descriptive names may have evolved as a result of an incomplete understanding of the exact cause and pathophysiology of mucoid cysts
        
        
      • click here for an example image of a mucoid cyst
        
        
    • treatment
      • majority of cases require no investigation or treatment (2)
        • an x-ray will demonstrate underlying OA of the distal interphalangeal joint (DIPJ)
      • a variety of techniques have been described for the treatment of digital mucoid cysts
        • range from puncture, aspiration and drainage, unroofing with electrodessication, injection therapy with steroids or sclerosing alcohol, curettage and compression, multiple needling and drainage, and simple surgical excision
          • aspiration is rarely effective and the cyst often reaccumulates. Infection of the cyst can lead to a septic arthritis of the DIPJ. The cyst can be surgically excised for cosmetic reasons or if the cyst is sufficiently large or painful to interfere with the nail or hand function (2)

Reference:

• 1) Blume PA et al. Digital mucoid cyst excision by using the bilobed flap technique and arthroplastic resection. The Journal of Foot and Ankle Surgery 2005;44, 44-48.
• 2) Arthritis Research UK (April 2013). The upper limb in primary care. Part 2: Wrist, hand. Hands On 2(7).