Sunday, February 14, 2010

Pearls and Ganglion Cysts

Our bodies can develop various lumps and bumps, and when they are near the skin surface, they become noticeable. Various terms are used to describe these bumps, often at the whim and creativity of the clinician e.g. "pea-sized", "pearl sized", and the like.

A real pearl is a hard, rounded object composed of calcium carbonate, created within a living mollusk:

They come in various colors, and are treasured for their beauty. The vast majority of pearls are cultured pearls, as natural pearls are quite rare.

A common pearl-sized bump in the area of the wrist is a ganglion cyst. Here is an example of a ganglion cyst on the volar side of the wrist:

Photo by Glen E. Malone

When they arise from the volar aspect of the wrist, common locations include the radioscaphoid/scapholunate interval, scaphotrapezial joint, pisotriquetral joint, and the metacarpotrapezial joint. When they arise dorsally, they are typically near the scapholunate joint and dorsal wrist capsule. Other sites include the extensor tendons, the carpal tunnel, and the Guyon canal. Ganglions may also arise within bone; these are called intraosseous ganglion cysts. Finally, ganglions can also arise near and within tendons and ligaments.

In this case, a 34 year-old female presented with a dorsal wrist mass. Axial T1 image reveals a smoothly marginated mass (red arrows) deep to the ECRL and ECRB tendons:

Axial T2 fatsat image shows the mass to be of homogeneous fluid signal intensity:

Coronal intermediate and T2 fatsat images depict the ganglion cyst (red arrows) and demonstrate a small neck (green arrows) leading to the scapholunate ligament (yellow arrows):

Dorsal ganglion cysts are often related to the scapholunate (SL) ligament. The SL ligament typically can still be identified, but is often increased in signal, indicating tissue degeneration.

When one detects a ganglion cyst on imaging, it is important to look for a "neck" or "pedicle", as in this case. The neck often points to the origin of the cyst, which can be important presurgical information. Small dorsal ganglia may not be palpable clinically, but may be painful. Cysts can get larger and smaller over time, and can resolve spontaneously in some cases. An excellent review of wrist ganglion cysts has been written by Gude and Morelli, and is worth reading. They have a nice section on management of ganglion cysts, with a fascinating description of alternate, historical methods of treatment:

Heister in 1743 had this recommendation: “The inspissated matter of a ganglion may often be happily dispersed by rubbing the tumor well each morning with fasting saliva and binding a plate of lead upon it for several weeks successively … Others … prefer a bullet that has killed some wild creature, especially a stag. Sometimes, indeed, a recent ganglion will speedily vanish … by adding a repeated pressure with the thumb or a wooden mallet. If none of these means prove effectual … they may be safely removed by incision provided you are careful to avoid the adjacent tendons and ligaments. But as for rubbing them with the hand of a dead man and the like … I presume, my reader will excuse me from insisting on them”

We now have different means to manage ganglion cysts, typically surgical excision. Not as creative as the methods described by Heister, but more effective....

Vic David MD