Cyst

Cyst (Gk. kustis, a bag or pouch). A cyst is well exemplified by such structures as the gall-bladder or urinary bladder - i.e. it is a bag containing fluid. The term cyst is, however, commonly applied not to these normal structures but to "fluid tumours" of new formation. Thus there is the blood cyst, the synovial cyst, or enlarged bursa (q.v.), the serous cyst as in hydrocele (q.v.), the sebaceous cyst (q.v.), and so forth.