CYST - a pathological cavity in organs and tissues, having a wall and contents. The size of such cavities, the structure of their walls and the nature of the contents vary depending on the origin of cysts, the duration of their formation, localization, etc. There are true cysts, the inner surface of which is lined with epithelium (less often endothelium), and false cysts (pseudocyst) devoid of a special lining. Cysts are acquired and congenital.
According to the mechanism of cyst formation, they are divided into retention, ramolation, parasitic, traumatic, dystogenetic and neoplastic. Retention cysts (as a rule, acquired) are formed in the glands, for example, salivary, sebaceous, lactic, due to the violation of the secretion produced by them. The latter, accumulating in the ducts of the gland or its lobules, stretches them, and a cavity is gradually formed with greasy, slimy, watery or other contents.
Ramol cysts (softening cysts) form in the necrotic focus after aseptic disintegration and resorption of necrotic masses. The wall of such a cyst is formed by an organ tissue, which can later be replaced by connective tissue. Ramol cysts are found in the brain, tumors, alveolar process or body of the jaw, as well as in the bone tissue in the areas of its dystrophy.
Traumatic cysts result from damage to the epithelial tissue with their displacement. Localized on the hands, in the iris, sometimes in the pancreas and bone tissue.
The formation of dysontogenetic (congenital) cysts is associated with the expansion of the surviving embryonic channels and pockets or with the abnormal development of parenchymal organs. Dysontogenetic include branchogenic cysts, which are located along the lateral surface of the neck; median cysts arising from the reduced thyroid duct; Parovarial cysts, multiple cysts of the kidneys, liver and others. Often there are dermoid cysts containing elements of the ectoderm (horny masses, hair, etc.).
Tumor cysts form in glandular tumors, such as ovarian cysts.