Background

Mucous cysts are ganglions of the distal interphalangeal joint (DIP) of the hand or of the toes. They have had several other names, including mucoid cysts, synovial cysts, myxoid cysts, and myxomatous cutaneous cysts.^{[1, 2, 3, 4, 5, 6, 7, 8, 9]}

Apart from the cosmetic deformity, patients with mucous cysts may note chronic drainage, infection,^[10]  and pain. Infections that develop from a ruptured cyst communicate with the underlying joint and can become septic arthritis and osteomyelitis. The pain may be secondary to the arthritic joint, as well as to the cyst itself. Additionally, the cyst may weaken the terminal extensor tendon with a resultant mallet finger.^{[11, 12]}

Treatment options in the past have included aspiration, electrocautery, chemical cautery, steroid injection, and various types of surgical excision. Surgery currently is considered the definitive treatment for mucous cysts.

Next

Pathophysiology and Etiology

In 60-80% of cases, mucous cysts are associated with degenerative joint disease of the DIP joint. Studies have shown a pedicle between the cyst and the DIP joint capsule.^{[13, 14, 15]}

The precise etiology of mucous cysts is unclear; theories include synovial herniation, extensor retinacular metaplasia, myxomatous degeneration, and excess hyaluronic production by fibroblasts.

Epidemiology

Mucous cysts are most common in the fifth through seventh decades of life. They are substantially more common in women, who constitute roughly 70% of the patients.

Prognosis

The recurrence rate with both cyst and osteophyte excision is 3-12%, compared with a 25-50% recurrence rate with cyst excision alone.

Lee et al conducted a retrospective review of the medical records of 37 patients (42 cases) who had mucous cysts combined with Heberden's node.^[16]  Osteophyte excision without cyst excision was performed. In all cases except one, the cyst regressed without recurrence or a skin complication after osteophyte excision; eight patients experienced postoperative pain and loss of range of motion.

Clinical Presentation