What is a ganglion cyst on the back side of the finger?

A ganglion cyst on the back of the finger is a pocket of lubricating fluid from the underlying joint (figure). Another name for this is a mucous cyst. They are typically associated with underlying arthritis.1,2,3

Ganglion cysts may look unusual, but they are harmless. 1,2,3


 ganglionb ack.jpg

Figure: a ganglion cyst.

Signs and symptoms

Ganglions can feel as hard as a bone. The underlying arthritis may cause pain, but the cysts do not. The cyst can be prominent. There may be a groove in the fingernail. If popped, the cyst may leak fluid. If it gets red, warm, and painful, it might be infected. This is uncommon. 1,2,3


The diagnosis is usually clear on examination.3