What is a Ganglion Cyst?

A ganglion cyst is a firm, fluid filled lump that can suddenly appear on the front or back of the wrist or at the base of a finger.  These cysts grow from normal tissue in the wrist and fingers, and range in size from a pea to a peach pit. Although ganglion cysts are common, they don't spread, and they don't become cancerous.  They can occur after an injury, but many times it isn't known why they grow.  Ganglion cysts can change in size, and may go away on their own.