Synovial Cyst:
A nodular, tumorlike lesion in or about a tendon sheath or joint capsule, especially of the hands, wrists, or feet. It is not a true cyst as it lacks an epithelial wall, and it does not communicate with the underlying synovial space. The lesion represents a focal accumulation of mucin in the dermis of the dorsal aspect of the distal phalanges or, less often, other portions of the extremities.