In which circumstance would you encounter a ganglion cyst?

A ganglion cyst is a fluid-filled sac that commonly appears near joints and tendons in the hands and wrists. The outer surface of the wrist is a well-known location for these cysts to develop, often presenting as a bump or swelling on the wrist. They are benign and typically occur in areas where there is repetitive use or stress on the joints, making the wrist an ideal location for their formation.

The other options, while they could involve other types of masses or conditions, are not commonly associated with ganglion cysts. For example, a ganglion cyst is less frequently found on the knee joint, back, or abdomen compared to the wrist, where the prevalence of such cysts is notable. Therefore, the presence of a ganglion cyst is most classically associated with the outer surface of the wrist.