Skin rash (skin rash)

Primary morphological elements

In the diagnostic respect, the most important are the primary morphological elements, in the nature of which (color, shape, size, outlines, consistencies, etc.) in a significant number of cases can determine the nosology of dermatoses.

Spot (macula) - a limited area of the skin of a changed color, without changes in its relief and consistency. The spot is at the same level as the surrounding skin. The spots are vascular, pigmented and artificial. The reasons for the appearance of spots - hypopigmentation or depigmentation (for example, vitiligo) and hyperpigmentation - the accumulation of melanin (for example, a stain of the type "coffee with milk" with neurofibromatosis, Mongolian stain or hemosiderin), abnormalities of the development of the skin vessels (for example, capillary hemangioma), temporary expansion of capillaries . Erythema, or hyperemic, is called a stain caused by a temporary expansion of the capillaries. The size of the spots is from 1 to 5 cm or more in the dimer. The erythematous spot up to 1 cm in diameter is called roseola (for example, syphilitic roseola). With diascopy, the hyperemic spot disappears. Stains, formed due to the release of red blood cells beyond the vessels, are called hemorrhagic. Small hemorrhagic spots are called petechiae, large - ecchymosis. Artificial stains (tattoo, tattoo) appear as a result of the deposition of insoluble coloring substances in the skin.

Nodule (papula) is the primary asphalt surface morphological element, characterized by a change in skin color, consistency and resolving without scar formation. Papules usually protrude above the surface of the surrounding skin, they can be palpated. Papules can be formed as a result of the deposition of exogenous substances or metabolic products, cellular infiltration or local hyperplasia. The surface of the papule can be smooth (for example, red flat lichen) or covered with scales (for example, psoriasis). Nodules can be inflammatory and non-inflammatory. Papules formed as a result of the proliferation of keratinocytes or melanocytes are clearly delineated from the surrounding skin. The deeper papules formed by the cellular infiltrate have vague boundaries. With a number of dermatoses, there is a peripheral growth of the papules or their fusion and the formation of larger elements - plaques (eg, fungal mycosis). Plaque (plax) is a flattened formation, raised above the level of the skin and occupying a relatively large area. As a rule, plaques have clear boundaries.

The tuberculum (tuberculum) is the primary asphalt formation that results from the development of a granulomatous infiltrate (granulomas) in the dermis. Clinically it has quite a lot of similarities with papules. Bugorok has clear boundaries, rises above the level of the surrounding skin. The diameter of the tubercles is from 5 mm to 2-3 cm, color from pinkish-red to yellow-red, copper-red, bronze, and cyanotic. With diascopy, the color of the tubercles can vary (tuberculous tubercles). Bumps have a dense or a testic consistency. They occur in limited areas of the skin, tend to group (for example, syphilis) or fusion (eg, tuberculosis). Unlike nodules, a scar remains in place of the tubercles (in case of its decay - with the formation of ulcers) or cicatricial atrophy (with resorption of tubercle infiltrate). The tubercles consist of epithelioid and lymphoid cells with an admixture of giant cells, that is, a tuberculoid structure, which is of great importance in diagnosing diseases such as tuberculosis, syphilis, leprosy, and others.

Nodule (nodus) is a primary, amorphous, infiltrative formation of a round or oval shape located in the deep sections of the dermis or subcutaneous tissue. The node differs from the papule in large sizes (from 2 to 10 cm or more in diameter) to the depth. Nodules can be mobile or soldered to the skin, can result from limited nonspecific inflammation (eg, erythema nodosum), specific inflammatory reactions (eg, skin tuberculosis) or a tumor process (eg, dermatofibroma). Nodes have a soft or dense consistency. The histological node can be represented by the deposition of metabolic products in the dermis or subcutaneous tissue.

Vesicula (vesicula) is a primary cavity formation that contains a serous or serous hemorrhagic fluid and rises above the skin level in the form of semi-spherical or round outline elements 1.5-5 mm in size. The vial has a wall, a cavity and a bottom. The walls of the bubble are so thin that through the peak the contents - plasma, lymph, blood or extracellular fluid are visible. Vesicles are formed when the epidermis separates (intraepitermal cavity) or when the epidermis exfoliates from the dermis (subepidermal cavity). The detachment of the stratum corneum of the epidermis leads to the formation of subcorneal vesicles. This occurs, for example, in impetigo and subcorneal pustular dermatosis. The immediate cause of the formation of intra-epidermal cavities are intercellular edema or spongiosis. Spongia is observed in allergic reactions of delayed type (eg, allergic contact dermatitis) and dyshidrotic eczema. The contents of the bubble quickly shrinks, turning into a crust. If the wall of the bubble is damaged, erosion is formed.

Bubble (bulla) is a primary limited cavity formation 0.5-0.7 cm in diameter and larger, consisting of a bottom, a tire and a cavity. The bubble contains liquid and protrudes above the level of the skin; has sharp boundaries, rounded or oval outlines. Often bubbles are single-chambered. When merging several bubbles or large bubbles (for example, with dyshidrosis, bullous epidermophytia), multi-chambered bubbles can arise. The contents of the blisters are serous, bloody or purulent. The cover can be tight, tense (for example, with herpetiform dermatitis) or flabby (for example, with vulgar pemphigus). Bubbles can be located on the inflammatory base (for example, with herpetiform dermatitis Dühring) or on the skin that is not changed in the outward appearance (for example, vulgar pemphigus). The cavity of the bladder is located intraepidermally (for example, with usual or leaf-like pemphigus, subcorneal pustules) or subepidermally (for example, with Lever's pemphigoid, Dhering's herpetiform dermatitis). When the bubble covers are destroyed, erosion is formed, along the edges of which there are scraps of the bladder cover. Sometimes the contents of the bubble are poured into the crust, after the rejection of which no trace remains. Subepidermal bladders leave scars after resolution (for example, in dystrophic bullous epidermolysis, bullous porphyria, etc.).

Pustula is the primary band morphological element containing purulent or purulent-hemorrhagic exudate. Purulent exudate can be white, yellow or yellow-green in color. Pustule develops around the hair follicles (more often - staphylococcal) or on smooth skin (more often - streptococcal). The size and shape of the pustules are different. The pustule, confined to the hair follicle, is called the folliculitis. It has a conical shape and in the center, as a rule, is permeated with hair. A superficial pustule, the contents of which quickly shrieks into a crust, is called a flickea (for example, with impetigo). Superficial pustules after healing leave temporary de-or hyperpigmentation, and deep-scars.

Bladder (urtica) is the primary cellless morphological element (papule or plaque) with a flat surface, which occurs when the upper sections of the papillary layer of the dermis are swollen. The pathognomonic sign of the blister is its ephemerality: they usually last no longer than several hours and are accompanied by itching and burning. Blisters can have a smooth smooth surface, round, annular or irregular shape. Due to the movement of the edema of the dermis, the shape and size of the blisters change rapidly. The color of the element is pale pink.

Secondary morphological elements

Dyschromia (dyschromia cutis) - pigmentation disorders that occur on the site of resolved primary or secondary morphological elements of the rash, corresponding to their magnitude and outlines. Distinguish secondary hyperpigmentation, de- and hypopigmentation. Hyperpigmentation in place of the former primary elements is formed as a result of the deposition of melanin (with melasma) and hemosiderin (with hemorrhagic spots). Reducing the melanin content in the skin causes the development of secondary hypo- and depigmented spots (with pigmentless nevus, vitiligo). Secondary hyper- and hypopigmentation disappear without a trace.

Scale (squama) is the loosened torn cells of the stratum corneum of the epidermis. As you move from the basal layer to the surface, keratinocytes lose nuclei and other cellular organelles and turn into a horny substance. Normally, in a healthy person, a complete change of epidermal cells - keratinocytes occurs every 27 hours. The process of sloughing is invisible. With increased proliferation of epidermal keratinocytes, a violation of the process of cell differentiation is observed, and cells with nuclei (parakeratosis) are found in it, and scales appear on the surface of the skin. Scales are large (lamellar peeling), medium or small, like dust (mucous peeling). They can easily separate (for example, with psoriasis). Difficultly separated scales are formed, for example, in keratodermia, ichthyosis, sunny keratosis. The skin becomes thick, rough, like rough sandpaper. Occasionally, impregnation of the scales with exudate and the formation of scaly crusts are observed.

Crusta (crusta) occurs when the contents of bubbles, bubbles, separated (purulent exudate, blood or plasma) from the surface of erosion and ulcers. Distinguish serous, purulent and hemorrhagic crusts. Cortex formed by dried plasma, have a yellow color, pus - green or yellow-green, blood - brown or dark red. Surface thin crusts of honey color are characteristic for impetigo. Crusts can be thin, brittle, easily crumbling or thick, welded to the skin. If the exudate permeates all layers of the epidermis, it is difficult to separate the thick crusts. If there is necrosis of the underlying tissues, the element is called ecthymoma. Numerous, massive, conical, purulent-hemorrhagic crusts were called rupees.

A crack (rhagades, fissura) - linear defects (breaks), arising from loss of elasticity and infiltration of individual skin areas. Cracks are often accompanied by soreness. There are superficial and deep cracks. Surface cracks develop within the epidermis and often occur with xerosis of the skin, eczema of the hands and feet, interdigital epidermophyte of the feet, infectious and yeast lesions of the corners of the mouth, etc. They quickly epithelize and regress without a trace. Deep cracks are localized within the epidermis and dermis, often bleed with the formation of hemorrhagic crusts, are painful, regress with scarring (for example, Robinson-Fournier scars in syphilis).

Erosion (erosia) is a superficial defect in the epidermis, while the dermis remains intact. Erosion occurs after the opening of the cavity elements - vesicles, blisters and surface pustules. Erosions have the same outlines and dimensions as the primary elements. However, they can be primary during mechanical irritation of the epidermis during combing (for example, with an itchy old pruritus), as well as due to maceration and friction of the contacting surfaces of the epidermis. Sometimes erosions are formed on papular eruptions, especially when they are located on the mucous membranes (for example, papular erosive syphilis). With the healing of erosion, the scar does not remain, but temporary hypo- or depigmentation may be observed.

Ulcer (ulcus) is a deep defect in the skin, in which the epidermis and papillary dermis are lost. Deep ulcers seize all layers of the dermis and subcutaneous tissue. Ulcers can occur when autopsy of tubercles, nodes or deep pustules; they differ from the wound, which is a defect in healthy tissues. In ulcers, the bottom and edges are distinguished, which can be soft (for example, with tuberculosis) or dense (for example, with skin cancer). Ulcers always heal, forming a scar.

The scar (cicatrix) occurs when healing ulcers, tubercles, nodes. Within the scar there are no appendages of the skin (hair follicles, sebaceous and sweat glands), as well as vessels and elastic fibers. Therefore, the surface of the scar is devoid of grooves characteristic of the normal epidermis. The epidermis in the scars is smooth, sometimes has the appearance of tissue paper. Scars can also form without previous ulceration, called dry path. Fresh scars have a pink-red coloration, their surface shines. Older scars can be hyper- or depigmented. Clinically distinguish between flat scars lying on the same level as normal skin, hypertrophic, thickened, rising above the surface of the surrounding skin (keloid scars) and atrophic when the surface is thinned and is below the surface of normal skin. Cicatricial atrophy occurs with resorption of a deep-seated infiltrate without compromising the integrity of the epidermis.

Vegetations (vegetationes) are characterized by proliferation of papillae of the dermis, thickening of the thorny layer of the epidermis on the surface of various pathological elements: papules, inflammatory infiltrates, erosions, etc. Sometimes the surface of the vegetation can be covered with a stratum corneum. Such vegetations have a grayish color, they are dry and dense on palpation (for example, with warts). With vegetating pemphigus, for example, the vegetation surface is eroded. Clinically, they are presented in the form of soft, juicy, easily bleeding, pinkish-red coloration of villous-like formations, covered with serous or serous-purulent discharge. Rapidly growing vegetation in appearance resemble cauliflower (for example, genital warts). Vegetation often occurs at the bottom of erosive and ulcerative defects.

Lichenification (lichenoficatio) is characterized by thickening and thickening of the skin, strengthening the skin pattern due to papular infiltration, which in combination resembles shagreen skin. Lichenization occurs as a result of constant scratching, most often in people with allergic diseases. It occurs in atopic dermatitis, mushroom mycosis, Vishal's simple diarrhea.

Abrasion, or excoriation (excoriatio) is manifested by a violation of the integrity of the skin as a result of mechanical damage. Often, excoriations occur due to strong scratching with nails or other objects during intense itching (neurodermatitis, eczema, etc.). They are usually linear, striped or rounded. Abrasions can be superficial, leading only to a violation of the integrity of the epidermis and papillary layer (disappear completely), and deep, penetrating into the deep sections of the dermis (leaving scars).

Excoriations can capture any primary element, more often a vial, a pustule, a nodule. In such cases, the abrasion corresponds to the magnitude of the element subjected to excoriation. For example, in scabies, excoriations correspond in shape to vesicles. Exocorations can also be caused by pathology.

Primary affect

Primary affect - a specific lesion of the skin at the site of the pathogen, often with concomitant regional lymphadenitis. It occurs in infectious diseases with a transmissible or (more rarely) contact mechanism of transmission of the pathogen. The appearance of primary affect, as a rule, precedes other symptoms of the disease and serves as an important diagnostic symptom.

Enanthema - a local discrete lesion of the mucous membrane, similar to skin rash. It has an important clinical and diagnostic value.