Cyste (Cyst) er en lukket pose, som kan indeholde luft, væsker eller halvfast materiale. En samling af pus kaldes en byld, som ikke er en cyste. Cysten skal muligvis fjernes kirurgisk, men det afhænger af dens type og placering.
A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that has grouped together to form a sac (like the manner in which water molecules group together to form a bubble); however, the distinguishing aspect of a cyst is that the cells forming the "shell" of such a sac are distinctly abnormal (in both appearance and behaviour) when compared with all surrounding cells for that given location. A cyst may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst may resolve on its own. When a cyst fails to resolve, it may need to be removed surgically, but that would depend upon its type and location.
Ganglion cyst ― Asymptomatiske klumper, der pludselig opstår mellem leddene. Hvis diagnosen ganglioncyste bekræftes, kan problemet løses ved at trykke hårdt på knuden for at sprænge cysten indeni.
Mucocele ― Det fremstår som en blød bule på læberne uden symptomer.
