Causes & Symptoms
Their exact cause is not totally understood but they are thought to be the result of repetitive microtrauma to the affected area, which in turn causes the lining of the joint (the synovium) to fill with excess fluid (synovial fluid rich of hyaluronic acid) produced by specialised cells which are present in that area (fibroblasts).
The fluid-filled sac which forms is the final result of this process and its content is clear and thick, which gives the cyst its peculiar feature of transillumination (light can pass through it). Sometimes a subtle instability of the bone of the wrist might cause irritation of the joint generating fluid that remains trapped in a cul de sac of the joint by a valve mechanism, creating a ganglion cyst which is under tension. When there is a local tension the cyst might become very uncomfortable and painful.
While the nature of ganglion cyst is completely benign (they are not cancerous), those affected often mention the aesthetic appearance. Patients may find that the cyst comes and goes, with its size varying, so that it is sometimes very painful and can interfere, at its largest size, with normal hand function. Nevertheless, their impact is somewhat variable: for some people it may become rather bothersome, for others it may be of little concern, if any.