Eczematous skin reaction (eczema): causes, symptoms, diagnosis, treatment

Among the various dermatoses, the eczematous reaction is one of the most common. This is an intolerant reaction to various irritations. It can be caused by a variety of factors, both endogenous and exogenous, leading to damage to the epidermis. Localized foci of damaged epidermis lead to a local increase in osmotic pressure, accompanied by increased movement of tissue fluid from the dermis into the epidermis, leading to the formation of vesicles in it, and when it moves to the surface, to the formation of so-called serous wells.

Clinically, in this reaction, mainly erythemato-vesicular manifestations are found in the acute period, and in chronic course polymorphism is expressed due to nodules, erosions, scaly crusts. The main element of this reaction is the spongeotic vesicle.

At the heart of the eczematous reaction are immune disorders, similar to those with allergic contact dermatitis. For the most part, the eczematous reaction is a consequence of the antigen-antibody reaction. Immunocompetent T-lymphocytes produce mediators (lymphokines) as a result of the action of the corresponding antigens, and transformed lymphocytes are a factor of macrophage inhibition and a free histamine cytotoxic factor, which leads to corresponding changes in the epidermis. A.A. Kubanova (1985) attaches great importance to the development of allergic reactions of patients with eczema to the prostaglandins of group E, which is in close connection with the formation of cAMP inhibiting the release of mediators of allergic reactions (histamine, etc.). In the author's opinion, increased synthesis of prostaglandins and disturbances in the adenylate cyclase system lead to the development of the inflammatory skin reaction and are one of the links that cause the development of immune disorders and the increase of allergic reactivity.

Pathomorphology of eczematous skin reaction (eczema). When the eczematous reaction, regardless of its variety, the histological pattern is of the same type and is modified only depending on the severity of the process.

In acute eczematous reaction, the dynamics of the process is characterized by several consecutive clinico-morphological phases.

The erythematous phase is manifested by reddening of the skin in one or more places. Histologically, edema of the upper half of the dermis is observed, limited mainly lymphocytic infiltrates and vasodilatation of the papillary dermis.

In the papular or papular-vascular phase, nodules appear on the erythematous base with a diameter of up to 1 mm, on the surface of which vesicles rapidly form. Histologically, in addition to edema and lymphocytic infiltrates in the dermis, spongios, acanthosis with lengthening of epidermal processes, parakeratosis and small vesiculation are found.

In the phase of vesiculation, the most characteristic for this reaction, in the zone of the blisters there is a significant spongiosia with the widening of the intercellular spaces, destruction by desmosomes and the formation of blisters of various sizes containing lymphocytes and serous fluid. There are also subcorneal blisters. If the process is complicated by pustulization, the vesicles become pustules filled with a large number of granulocytes. In the epidermis there are pronounced acanthosis and exocytosis, and in perivascular dermal infiltrates a significant amount of eosinophil granulocytes appears.

The formation of crusts is associated with the drying of serous exudate on the surface of the epidermis. They are permeated with disintegrated neutrophilic granulocytes and epithelial cells, while in the dermis, edema and infiltration are less pronounced.

The squamous phase is characterized by epithelialization of lesions and rejection of scales and scales. Histological examination of acanthosis and parakeratosis with exfoliation of the stratum corneum, minor edema of the upper dermis.

Electron microscopic examination of the skin in the acute period of this reaction revealed intracellular edema with the formation in the cytoplasm of epithelial cells of various size vacuoles located around the nucleus (perinuclear gland). The nuclei are in various stages of edematous degeneration, often with dilution of large areas of karyoplasm. Tonofilament sharply swollen, homogeneous, do not have clear boundaries: mitochondria, cytoplasmic network, the apparatus of Hodja are not determined. Clumps of keratogialin in the granular layer are not visible, which indicates a sharp hypoxia of epithelial cells. With increasing edema, vacuoles appear not only near the nucleus, but also on the periphery of the cytoplasm of epithelial cells. In the dermo-epidermal zone, a dense plate rupture occurs, through which fluid and blood elements move to the epidermis from the dermis. In the dermis, the venous plexus of the papillary layer, which participates in the formation of a strong edema of these parts of the dermis, is primarily involved in the process. In the vessels, hypertrophy of endotheliocytes without pronounced necrosis of cells and a sharp narrowing of the lumens are revealed. When studying the morphology of perivascular infiltrate cells, it was shown that inflammatory cells consist mainly of B-lymphocytes.

The chronic stage of the eczematous process can develop as a continuation of the acute or subacute stage as a result of constant exposure to the stimulus for a long time. Foci of chronic eczema have a characteristic livid red color. Infiltration of the skin, increased its relief, a tendency to cracking and peeling. Histologically, vasodilation in the upper half of the dermis, perivascular infiltrates consisting of histiocytes with a small amount of lymphocytes are observed; Edema, as a rule, is weakly expressed. In the epidermis - acanthosis, massive hyperkeratosis, in some places the multi-row basal soda, sometimes parakeratosis. Electron microscopy revealed a decrease in edema in this phase, although the structure of desmosomes remains impaired. In the cytoplasm of epithelial cells, a large number of ribosomes were found, many large mitochondria with dystrophic changes in them.

R. Jones (1983), as a result of an ultrastructural study of the skin in various stages of the process, showed that early changes always begin with the dermis, more precisely from its vascular apparatus, accompanied by a sharp edema of the papillae, from which edematic fluid is eliminated into the epidermis through the dermoepidermal membrane, intracellular edema in the form of vacuolation of epithelial cells with subsequent rupture of their membranes and cell death with the formation of spongyotic vesicles.

Histogenesis of eczematous skin reaction (eczema). In the development of eczematous reactions, an important role is played by humoral immune factors. By carrying out a quantitative study of immunocompetent cells of peripheral blood (T- and B-lymphocytes), V.L. Loseva (1981) showed that the number of T-lymphocytes in patients with various forms of eczema is slightly increased. When studying the infiltration of the dermis, it turned out that the basis of the infiltrate is made up of immune lymphocytes and degranulated tissue basophils, as well as macrophages. Studying fingerprints and tissue fluid by the "skin window" method at various stages of the eczematous reaction, the same author showed that in the acute period, along with the migration of a large number of lymphocytes, tissue eosinophilia is observed. In the subacute phase, mainly macrophages migrate, which indicates the role of hypersensitivity of both types in the pathogenesis of ectematous reactions. The clinical, physiological, biochemical and pathomorphological studies carried out by her suggest that all clinical forms of eczema are essentially a single pathological process with a common pathotene mechanism.

It should be noted that the most pronounced immuno-morphological shifts are observed in contact and especially with microbial eczema. At the latter in the dermal infiltrate, electron microscopy can be used to see clusters of small lymphocytes, among which are activated forms with well-developed organelles and large cerebral nuclei, macrophages, cells with high synthetic protein activity, differentiating into plasmocytes, and degranulated forms of tissue basophils. Contacts of epidermal macrophages with lymphocytes were noted. With contact eczema, there is an increase in the number of epidermal macrophages, often in contact with lymphocytes, edema of the epidermis with the presence of lymphocytes and macrophages in the expanded intercellular spaces. In the dermal infiltrate, a large number of macrophages with a variety of lysosomal structures are found. Lymphocytes sometimes have a cerebriform nucleus and well-developed organelles.

Changes in vessels are similar to those in experimental contact dermatitis and are characterized by signs of hypertrophy and hyperplasia of the endothelium and perithelium. Thickening and duplication of the basal membrane.

The above data on the histogenesis of the eczematous reaction are indicated in the processes typical for delayed-type hypersensitivity.

In the development of the eczematous reaction in various cases, a definite clinical and morphological picture is revealed depending on the effect of a complex of adverse factors, including infection. In this regard, distinguish dishydrotic, microbial and seborrhoeic eczema.

Dyshidrotic eczema is characterized by a rash, mainly on the palms and canvases, small bubbles that can merge into small bubbles, and after opening - erosive surfaces. Moisture is less pronounced than with true eczema. With a prolonged course, eczematic foci can appear in other parts of the skin. Secondary infection is often observed.

Pathomorphology. They identify intraepidermal blisters, sometimes so close to each other, that only thin layers of dead cells of the epidermis are visible between them. Vesicles can be spongy, as with true eczema. Some authors associate the formation of blisters with the dilatation and rupture of the duct of the sweat gland.

Microbial eczema. In the development of the disease is of great importance sensitization to pyogenic bacteria, it often develops as a complication of chronically current inflammatory processes (varicose ulcers, osteomyelitis and l.). Clinically appears as the presence of single, asymmetrically located on the skin of the distal parts of the extremities (especially on the shins), fairly sharply outlined, infiltrated, often dying, covered with scaly crusts of lesions, periphery of which reveal vesicle-pustular eruptions. With prolonged recurrent course, the appearance of exacerbations may occur in places remote from the main lesion.

Pathomorphology of eczematous skin reaction (eczema). The pattern resembles that of seborrheic eczema, but is usually characterized by massive spongiosis and the presence of blisters filled with serous fluid with an admixture of neutrophilic granulocytes, often acanthosis.

Seborrheic eczema. The development of the disease attaches importance to constitutional factors, metabolic disorders, dysfunction of the sebaceous glands. Foci of lesions are located on the so-called seborrhoeic sites in the form of rather sharply outlined yellowish-red plaques, oval, rounded or irregular contours, abundantly covered with scaly crusts, which gives them a psoriasisiform appearance. Often find out a diffuse otrebuschnoe peeling on the scalp, acne. Moisture is usually minor, with the exception of foci located in the folds.

Pathomorphology of eczematous skin reaction (eczema). Usually marked hyperkeratosis, parakeratosis. Intra- and intercellular edema and small acanthosis. Sometimes exocytosis, edema and various degrees of infiltration of the dermis, mainly of lymphocyte character, can be observed. In the field of varicose ulcers, dermal fibrosis is added to these changes, in which lymphohystocyte infiltrates are visible, often with the presence of plasmocytes. Sometimes acanthosis can be observed with an extension of the epidermal outgrowths, which resembles a picture of neurodermatitis or psoriasis. Perifolliculitis is often observed. Sometimes in the surface cells of the germ and horny layers, as well as in the endothelium of the vessels of the superficial dermal network, lipids are found, which is not the case with true eczema. In addition, the distinctive feature of seborrheic eczema is the presence of cocco flora in the superficial parts of the stratum corneum. In the dermis there is a perifollicular infiltrate containing lymphocytes, neutrophilic granulocytes, sometimes plasmocytes. Perhaps a small thickening of the walls of the vessels. Elastic and collagen fibers, as a rule, are not affected.

[1], [2], [3], [4], [5], [6]