Ganglion cysts are fluid-filled cysts found in different parts of the hand.  Such cysts can occur in any area where there is a synovial, or slippery, lining to either a joint or the sheath (lining) of the tendons.  They can therefore occur in many different places within the hand.
Although ganglion cysts may be sufficiently symptomatic to require surgical removal, often they will resolve spontaneously without any treatment whatsoever.  For this reason, enough time should elapse from the onset of symptoms and the discovery of the cyst to allow for spontaneous recovery.  Before surgery is considered appropriate, it is recommended that at least three to six months elapse without change to the cyst.

Cysts at the Back of the Wrist
The most common location of ganglion cysts of the hand is on the dorsal aspect (the back) of the wrist.  Such a cyst may reflect a minor injury to the wrist or to a ligament there.
Cysts on the back of the wrist often produce very little in the way of symptomatology, but if ongoing pain is experienced, then removal of the fluid with a needle (a procedure called aspiration) occasionally will reduce the discomfort.
If the symptoms continue, then removal of the cyst by surgery is needed.
With surgery of this type of cyst, it is important to remove the "stalk," or connection, down to the wrist joint where it usually originates.

Cysts at the Palm
The second common area for a ganglion cyst to occur is in the flexor tendon sheath in the palm of the hand.  This type of cyst is usually small, mobile, and moderately tender.
Such a cyst is sometimes amenable to removal of the fluid by aspiration with a needle.  However, if it persists and is symptomatic, it may prevent firm gripping of objects, in which case a minor surgical procedure may be called for to effect its removal.

Cysts of the Finger
A third common area for cysts in the hand is the back of the finger, adjacent to the nail and around the distal interphalangeal joint (the end joint).
These cysts usually arise from arthritis or a minor irregularity within the underlying joint.  Because they "communicate" with the joint, they do not benefit from aspiration (removal of the fluid with a needle) and will almost always recur.
If they are symptomatic or cause pain, enlargement, or nail deformity, such cysts must be removed with surgery.  The underlying joint needs to be cleaned out, or debrided, to avoid recurrence of the tumor.