Cyst

CYST (from Greek cystis - bladder). In anatomy, the term cystis is applied to denote certain hollow organs, for example, cystis fellea - gallbladder, cystis (more often-vesica) urinaria - urinary bladder. In pathology, however, the term C. is used to denote pathological cavities appearing in tissues, the size, structure, walls, and contents of which can be extremely diverse depending on the mechanism of formation of the C., its location, duration, etc. Pathological cysts are of five categories: retention, ramollition, on the basis of developmental defects and displacement of tissues, tumor, parasitic. 1. Retention cysts, or cysts from retention (e retentione), occur in various glandular-secretory apparatuses, where they form when obstacles arise to the secretion of the gland; the secretory product, accumulating either in the duct or in the glandular lobule, stretches them, forming a C. in the form of a gradually increasing spherical cavity with various (watery, mucous, colloid, fatty) contents depending on the gland's secretion and subsequent changes in it (thickening, sediments, transudation). Obstacles to the outflow of secretion, underlying the formation of retention cysts, can be various: sometimes this is--obstruction of the duct by a concrement, a plug of coagulated secretion; in other cases--compression of the duct by a tumor or connective tissue scar that developed as a result of inflammation or injury. There are also cases of congenital retention cysts on the basis of intrauterine atresias of ducts. Retention cysts have a wall, the structure of which corresponds to the structure of the given duct or gland with the difference that due to stretching and pressure from the contents, the elements of the wall, including the epithelial covering, are atrophied to one degree or another. Examples of retention cysts are atheroma, which is a retention cyst of a sebaceous gland, milk cysts (galactocele) of mammary glands, kidney cysts developing as a result of atresias of urinary tubules, the so-called ovula Nabothi, which are retention cysts of the uterine cervix glands, cysts of the ducts of salivary glands, pancreas, cysts of the common bile duct in atresia or underdevelopment. Retention cysts also include certain ovarian cysts that form as a result of stretching of the fluid of Graafian follicles, delayed in their normal maturation, the so-called follicular cysts. It should be noted that the concept of a retention cyst is very close to the concept of false hydrocele, under which is meant retention (from retention of secretion) stretching of a pre-existing normal cavity, and its contents, due to dilution with transuding fluid, takes on a watery appearance. This includes: hydrocele of the gallbladder when the cystic duct is closed, hydrocele of the vermiform appendix when its proximal part is obliterated, hydrocele of the Fallopian tubes (hydrosalpinx) when the ends of the tube are closed, hydrocele of the renal pelvis (hydronephrosis) when the ureter is closed. 2. Ramollition cyst, or cyst from softening (e ramollitione), is a cavity formed in compact tissue as a result of softening, disintegration of it on a limited extent; in this case, the products of disintegration, liquefying and being absorbed, are usually replaced by transuding watery fluid. Ramollition cysts do not have any special wall, and their edges are formed by the tissue in which softening occurred; only with time can proliferation of connective tissue occur in these edges (in the brain, glial tissue), which leads to the formation of a semblance of its own wall; there is never any epithelial lining in ramollition cysts. The most frequent basis for ramollition cysts is tissue necrosis, belonging to the category of colliquative necrosis, and the necrotic tissue undergoes rapid liquefaction and disintegration. In addition, such cysts can form as a result of hemorrhage into the tissue, its sharp edema, impregnation with inflammatory exudate. Ramollition cysts are most often found in the tissue of the brain (less often-spinal cord), where they represent the outcome of anemic infarcts, i.e., necrosis developing on the basis of closure of the artery's lumen by embolus, thrombus or proliferation of the inner membrane. Similarly, in various proliferations of neuroglia in the form of tumors, gliomas or gliomatosis, cysts from softening can form on the basis of insufficient blood supply to the proliferated tissue. Ramollition cysts can also include cysts of the yellow bodies (see) of the ovaries with the reservation that such a cyst, first forming on the basis of hemorrhage and degenerative changes of the cells of the yellow body, subsequently increases due to transudation of fluid into it. Cysts forming in tissues in various inflammatory and

CYS

reactive processes, in most cases also belong to ramollition cysts, since their basis is softening of tissue due to necrosis, hemorrhages, inflammatory edema, suppuration, for example, the so-called root dental cysts, or cystic dental granulomas. Bone cysts observed in fibrous osteitis are also ramollition, developing on the basis of softening from hemorrhages or serous edema. Finally, cysts from disappearance, atrophy of tissue can also include air cysts of the lungs in the so-called bullous emphysema. In contrast to this, gas cysts forming in tissues in gas phlegmon can be regarded simply as the result of tissue being pushed apart by the gases forming. 3. On the basis of developmental defects, not only retention cysts form in cases when the obstruction of one or another duct represents a developmental defect (see above). In addition, the development of cysts is observed due to transudation of fluid or accumulation of secretion in various rudimentary embryonic remnants; these include cysts from Morgagni's hydatids, paraovarian cysts, branchiogenic cysts, originating from preserved gill slits, cysts from remnants of the vitelline duct. Close to this are cysts developing on the basis of displacement of tissues during life, for example, traumatic epithelial cysts of fingers and palms, which are the result of traumatic implantation of the epithelial covering into the underlying tissue and subsequent accumulation of fluid in the epithelial pouch formed in the depth of the skin. An intermediate position between cysts developing on the basis of developmental defects and tumor cysts is occupied by cysts related to teratomas. These include the so-called dermoid cysts and cystic organismoid teratomas. 4. Tumor cysts belong to glandular and vascular tumors, in which either from accumulation of fluid in cavities or due to growth of elements of the cavity walls, their volume can increase and cysts form. In these cases, cysts are either single or multiple, and the formation of cysts in a tumor serves as the basis for corresponding terms. Thus, if in a glandular tumor, adenoma, cysts form due to expansion of glandular cavities, it is called cystadenoma (see Adenoma); if in a lymphangioma (see) there is a significant increase in the volume of lymph. cavities, then they speak of cystic lymphangioma; sometimes the tumor is simply designated as cystoma or in the case of many cysts--as polycystoma. 5. Parasitic cysts represent the vesicular stages (larvae) of tapeworms, having the appearance of blisters filled with fluid; these include echinococcal cyst, or echinococcus (see) and cysticercus. - From the term C. are formed the adjectives "cystic", "cystic" (cysticus), used in cases when this or that pathological change is accompanied by the formation of C.; for example, cystic granuloma, cystic tumor, cystic mastitis, endometritis. A. Abricosov.