KISTA is a pathological cavity in organs and tissues that has 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 the cysts, the age of their formation, localization, etc. True cysts are distinguished, the inner surface of which is lined with epithelium (less often endothelium), and false cysts (pseudocysts), devoid of special lining. Cysts are acquired and congenital.
According to the mechanism of formation of cysts, they are divided into retention, ramiolytic, parasitic, traumatic, dysontogenetic and tumor ones. Retention cysts (usually acquired) are formed in the glands, for example, salivary, sebaceous, mammary, due to impaired outflow of the secretion produced by them. The latter, accumulating in the ducts of the gland or its lobules, stretches them, and a cavity with sebaceous, mucous, watery, or other contents gradually forms.
Ramolytic cysts (cysts from softening) form in the necrotic focus after aseptic decay and resorption of necrotic masses. The wall of such a cyst is formed by organ tissue, which can be replaced later by connective tissue. Ramolytic cysts are found in the brain, tumors, alveolar bone or jaw body, as well as in bone tissue in areas of its dystrophy.
Traumatic cysts result from damage to epithelial tissues with their displacement. They are localized on the hands, in the iris of the eye, sometimes in the pancreas and bone tissue.
The formation of dysontogenetic (congenital) cysts is associated with the expansion of preserved embryonic channels and pockets or with an abnormality in the development of parenchymal organs. Branchiogenic cysts located along the lateral surface of the neck belong to dysontogenetic; median cysts arising from the reduced thyroid-lingual duct; parovarial cysts, multiple cysts of the kidneys, liver, etc. Often there are dermoid cysts containing ectoderm elements (horny masses, hair, etc.).
Tumor cysts form in tumors of glandular origin, for example, in ovarian cysts.