Infectious diseases

crust. If a blister is opened (damaged), soaking superficial pink or red erosion develops on its place.

Herpetic eruption (herpes) — a bunch of small closely set bubbles on the erythematic inflammatory base (herpetic infection, surrounding deprive).

Pustule (pustula) is also a blister but its contents is cloudy (purulent) because of a clump of a big amount of leucocytes.

Blister (bulla) — a cavity formation with a dimension of more than 5 mm (up to 10 cm and more). The borders of a vesica are legible, the outline is round or oval. The vesica rises above the level of the skin. It is usually unicameral and rolls off after a puncture. The cover of a vesica can be tight and flabby. The contents is serouse or serouse-hemorrhagic.

The vesicles can be situated on the background of the inflamed skin (a violent form of erysipelas, anthrax, multiform exudative erythema, Stivens -Johnson's syndrome).

Hemorrhages (hemorrhage) - an extravasation into the skin of different kinds and dimensions. They develop as a result of the erythrocytes yield from veins to the ambient connecting tissue of derma or hypodermic fatty tissue. It can be a result of the damage (breakage) of the vessel or heightened permeability and fragility of a vascular wall.

According to the value and form hemorrhages are divided into the following elements: petechias (petechiae) - dotted hemorrhages on the background of the normal skin (primary petechias) or on the background of roseolas (secondary petechias); purpura (purpura), in which the dimensions of the elements oscillate from 2 up to 5 mm (the dermatologists consider purpura to be hemorrhages with a diameter up to 2 cm): ecchymomas (ecchymosis) — hemorrhages of the irregular-shaped form with a diameter of more than 5 mm.

Ecchymoses (sugillationes) - hemorrhages on places of injections that are not the sort of an exanthema but have a diagnostic value as a parameter of a heightened fragility of vessels, that is often observed in the development of a hemorrhagic syndrome.

The hemorrhagic elements of the eruption are observed in many infectious diseases and have a great value both for the differential diagnostics and for the evaluation of the illness severity.

All the reviewed above exanthemas belong to the primary morphological elements of the eruption. However, the secondary morphological elements of the eruption also have a diagnostic value. The dyschromias of the skin, flake, peel, anabrosis. ulcers, seams belong to them.

Erosion (erosio) - a defect of the epidermis which develops after opening of the cavity primary elements (vesicles, pustules, vesica). The bottom of the erosion is covered with epidermis or partially with the papillar layer of the derma. By the size and form the erosion corresponds to the primary element. After healing the erosion do not leave any stable changes of the skin.

Ulcer (ulcus) - a deep defect of the skin which affects the epidermis, derma,

Introduction of infectious diseases 19

and sometimes underlying tissues. The ulcers develop as a result of the disintegration of the primary infiltrating elements in the deep parts of the derma - pimples, clusters, and the opening of the deep pustules. The form and the edges of the ulcer are of great importance for differential diagnostics. The edges of the ulcer can be undermined, vertical saucer-shaped, callous, mild, etc. The ulcer always heals leaving a cicatrix. The ulcers develop both in the infectious diseases (dermal leishmaniasis, anthrax, tularemia) and in the illnesses related with the competence of other specialists (lues, tuberculosis, trophic ulcers, neoplasm).

Skin dischromia (dyschromia cutis) - a disorder of the pigmentation, which develops on the place of the resolved morphological elements of the dermal eruption. The expressiveness and duration of the hyperpegmentation are various. As a rule, pigmentary spots are brown. Sometimes they are sharply distinguished, for example, after measles maculepapulas eruption, especially in case of its hemorrhagic impregnation. Sometimes it is only a hardly noticeable brown blot (for example, on the place of typoid roseola), which disappears fast and does not leave any traces. Scale (squama) is a loosened tearing away ceel of the corneous layer,which lost its connection with the underlying epidermis. Depending on the size of the flakes there is micro- and macrolaminar pityriasis.

Small-laminar, branny pityriasis (desquamatio pityriasiformis) is observed in measles, branny lichen. The smallest flakes get detached and the skin looks as though it is powered with flour.

Macrolaminar pityriasis (desquamatio lamallosa) is characterized with a larger dimension of the flakes, and they can get detached from the skin by the whole layers. The similar pityriasis is characteristic of scarlatina, pseudotuberculosis, toxidermias. The pityriasis develops in the period of convalescence from the infectious diseases and what is important for differential diagnostic - in the late period of illnesses or during reconvalescence.

Crust (crusta) - a product of thickening and desiccation of different kinds of other elements exudates of the eruption (pustules, vesicles, anabroses, ulcers). There are serouse crusts (semidiaphanous or grayish), purulent (yellow or green-yellow) and hemorrhagic (brown or dark red). The size of the crusts corresponds to the size of the preceding element.

Cicatrix (cicatrix) - coarse-fibroid growth of the connecting tissue, which substitutes deep defects of the skin.

The listed above elements of exanthema are basic and can be observed in infectious diseases, the differential diagnostics is based on their exposure. In case of the eruption it is necessary to identify the type of separate elements and, besides, to specify other peculiarities of exanthema.

The very important signs are the terms of the eruption development.

The localization of the eruption elements and the place of the greatest

concentration of exanthema are of a diagnostic value. In some cases the sequence

of the rush development is of the diagnostic value. The duration of the eruption

elements existence is also important. Repeated rashes and the inclination for

Date: 2014-12-21; view: 903