Sista (Cyst) ialah kantung tertutup. sista (cyst) mungkin mengandungi udara, cecair atau bahan separa pepejal. Pengumpulan nanah dipanggil abses, yang bukan sista. Sista mungkin perlu dibuang melalui pembedahan, tetapi keputusan bergantung pada jenis dan lokasinya.
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 ― Ketulan tanpa gejala yang berlaku secara tiba-tiba di antara sendi. Jika diagnosis sista ganglion disahkan, masalah boleh diselesaikan dengan menekan nodul dengan kuat untuk memecahkan sista di dalamnya.
Mucocele ― Ia kelihatan seperti benjolan lembut pada bibir tanpa sebarang gejala.
