Digital Mucous Cyst (DMC): Myxoid Cyst…

Hyde first described digital mucous cyst (DMC) in 1882 In 1893, Ledderhose suggested that ganglia arose spontaneously in the subcutaneous tissue.  Ritschel, in 1895, proposed the earliest formulation of the theory that mucoid degeneration may be responsible for digital mucous cysts; Carp and Stout popularized the theory in 1928.  They are also referred to as Myxoid Cyst, Synovial Cyst, and Digital Ganglion Cyst.

They occur most commonly on the dorsal or lateral terminal digits of the hands but may also afflict the toes.  The lesions present as solitary 5-7 mm, opalescent or skin-colored cysts.  They may occur as asympotmatic swellings of the proximal nailfold, as a subungual growth, or over the distal interphalangeal joint.  Some DMCs communicate directly with the joint space and can be reduced with pressure.  A characteristic groove may form along the proximal to distal nail at the site of involvement (See Above).  The cyst consists of clear viscous, jelly-like sticky material that is easy to express (See Below).

CAUSES:  DMCs are frequently observed in patients with significant degenerative joint disease or rheumatoid arthritis.  It is most often found in elderly individuals, however, multiple DMCs have been reported in young children and even infants with juvenile rheumatoid arthritis.

TREATMENT:  I usually treat them initially by poking it with a 30 gauge needle and expressing the jelly-like material.  Sometimes this is all that is needed, but most of the time they return and have to be treated again.  If I treat them 3 or more times my next step is to evacuate them then to inject kenalog into the cavity.  Injection of sodium tetradecyl sulfate (a sclerosing agent) has an 80% response rate but is not likely covered by insurance.  Others have had some success with carbon dioxide laser ablation, curettage and fulguration, but these therapies result in scarring.  Surgical resection may be required and is effective (90%).  In general these are very benign lesions and how aggressive one is depends on size, location and if there is nail involvement.  To read more about DMCs click HERE and HERE.