From Big Medical Encyclopedia

EPIDERMOID CYST (Greek epi-on, atop + derma skin + eidos a look; cyst; a synonym an epidermal cyst) — the cyst of skin, an inner surface a cut is covered by a multilayer flat epithelium, and contents are presented by horn scales.

Nek-ry researchers, e.g. D. I. Golovin (1958), Uorvi and Gates (W. N.Warvi, O. of Gates, 1943), considered E. to. as a malformation also explained its emergence with an otshnurovka of epidermis in an embryogenesis. It is confirmed by the fact that E. to. quite often find in a zone of embryonal lines of a smykaniye and they are combined with other malformations.

AA. to. meet at any age, it is equally frequent at men and women. They are localized preferential on the head, a trunk and upper extremities. Macroscopically E. to. represents tumorous formation of rounded shape, a soft consistence from from 5 to 40 mm in size and more. Skin over E. to. usually it is not changed, however in case of accession of consecutive infection can have a reddish shade. AA. to. it is mobile together with surrounding fabrics, is painless, grows rather quickly.

At microscopic examination on an inner surface E. to. the thinned epidermis without appendages of skin comes to light (see Skin), to-ry it is presented by all layers of normal epidermis; the cavity of a cyst is filled with horn scales.

Due to the penetration of pathogenic microflora into a cavity E. to. (is more often owing to a microtrauma or a hematogenous way) in it inflammatory process quite often develops up to abscessing. The epithelium covering E. to., in rare instances пролиферирз^ет, forming outgrowths in a cavity of cysts in the form of nipples. Contents E. to. can be exposed to calcification. At destruction of walls of a cyst its contents can get into a derma that leads to development hron. a nonspecific inflammation with existence in granulyatsionny fabric of colossal cells of a foreign body (see. Colossal cells).

The diagnosis is established on the basis by a wedge, pictures and data gistol. researches. Differential diagnosis is carried out with an atheroma — a sebocystoma, edges develops owing to obstruction of an outside opening of an output channel of this gland. Atheromas meet on the sites of skin rich with sebaceous glands (a pilar part of the head, a face, a neck and area of a tailbone). Growth of an atheroma slow, it is covered with normal skin (with it it is fixed), often suppurates. The inner surface of an atheroma is covered by a flat epithelium, her cavity contains a detritis, the keratosic cells of epidermis, a drop of fat, crystals of cholesterol. AA. to. it is also necessary to distinguish from dermoid cysts, to-rye have a dense consistence and spherical shape, and at gistol. a research in them find a vystilka from a multilayer flat epithelium with appendages of skin (see the Dermoid).

With the cosmetic purpose and at purulent fusion E. to. removal of a cyst in the operational way (under local anesthesia the cyst is excised together with its walls) is shown. In cases of abscessing E. to. it is opened, evacuate contents and drain a cavity; excision of walls of a cyst is carried out after subsiding of the inflammatory phenomena.

Forecast, as a rule, favorable. Malignancy E. to. it is observed seldom.

Bibliography: Apatenko A. K. Epithelial tumors and malformations of skin, page 66, M., 1973; In e N to e and T. and Shugar Ya. Malignant tumors of skin, the lane with Wenger., Budapest, 1962; Golovin D. I. Epithelial tumors of skin, page 27, Chisinau, 1958; Masson P. Tumors of the person, the lane with fr., M., 1965; The Multivolume guide to a dermatovenereology, under the editorship of

S. T. Pavlov, t. 3, page 605, M., 1964;

Oganesyan of Page 3. Epithelial courses and cysts of coccygeal area, Yerevan, 1970; Odinov D. E. and Shabanov of A. N. Hirurgiya of the ambulatory doctor, page 189, M., 1973; Pathoanatomical diagnosis of tumors of the person, under the editorship of N. A. Krayevsky, etc., page 442, M., 1982; Strelnikov B. E. Epithelial cysts of sacrococcygeal area, M., 1962; Albertini A.

Histologische Geschwulstdiagnostic, Stuttgart, 1974. N. P. Bychikhin.