Dermatovenerology. Psoriasis (most important)

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Dermatovenerology. Psoriasis (most important)

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LECTURE № 8. Psoriasis

Psoriasis, or psoriasis, is one of the most common chronic dermatoses, characterized by hyperproliferation of epidermal cells, impaired keratinization, and inflammation in the dermis.

Etiology. This is a disease of unknown etiology. One of the main hypotheses for its development is considered hereditary. It is assumed that the disease can be transmitted in an autosomal dominant manner. However, even in people with an unfavorable genotype, various provoking factors play a role in the occurrence of the disease.

1. Trauma. The occurrence of psoriatic rashes at the sites of skin injury of a physical, chemical or inflammatory nature, well known as the Koebner phenomenon.

2. Infection. The role of streptococcal and herpetic infections as the most likely variants of provoking infectious factors in psoriasis is generally recognized.

3. Endocrine factors. The peak incidence of psoriasis in puberty and menopause was noted. The development of inverse and exudative psoriasis is associated with dysfunction of the thyroid gland and adrenal cortex.

4. Insolation usually leads to clinical improvement, however, in the progressive stage of dermatosis and in patients suffering from the summer form of psoriasis, the skin process is exacerbated.

5. Medications can provoke both the onset of psoriasis and the exacerbation of the skin process.

6. Psychogenic factors can provoke both the onset of psoriasis and exacerbation of a skin or joint lesion.

7. Alcohol contributes to a more severe course of psoriasis.

8. HIV infection also causes a severe course of the disease.

Pathological signs of skin lesions in psoriasis.

1. Metabolic disorders. Violation of the content of calcium-regulating hormones predetermines the development of osteopathies and other changes characteristic of hyperparathyroidism.

Leukocyte attractants - a substance similar to leukotriene B was found in psoriatic plaques₄ and has a pronounced property to attract neutrophils.

2. Immunological mechanisms. The central pathogenetic event in psoriasis is the "mononuclear-keratinocyte" relationship, which leads to the activation of the latter with the release of inflammatory mediators and growth factor.

Pathomorphology. The changes are characterized by the following signs: infiltration of the dermis, elongation of some papillae, and the formation of glomeruli in them from full-blooded capillaries. Through diapedesis, leukocytes penetrate the epidermis and form Munro microabscesses under the stratum corneum. In the epidermis, interpapillary acanthosis, absence of the granular layer, and parakeratosis are also observed.

The peculiar morphological structure of psoriatic papules causes a triad of symptoms pathognomonic for psoriasis, which is determined by scraping the surface of the papule with a scalpel. Initially, as a result of crushing the scales, a picture is revealed that resembles that when a frozen drop of stearin is scraped off (a symptom of a stearin stain). Then, due to the absence of the granular layer, the compact lower rows of the stratum corneum peel off as a film, exposing the moist surface of the spinous layer (a symptom of the terminal film). Further scraping leads to damage to the capillaries in the elongated papillae with the appearance of droplets of blood (a symptom of blood dew).

Clinic. The primary rash in psoriasis is a flat, inflammatory epidermal-dermal papule of a round shape with clear boundaries, 1-2 mm in size, pink or deep red in color; on the lower extremities, papules often acquire a bluish tint. From the moment it appears, the surface of the papule begins to become covered with dry, loosely arranged silvery-white scales. As a result of peripheral growth, miliary papules turn into lenticular and nummular, adjacent rashes merge, forming plaques of various shapes.

In the progressive stage of psoriasis, an isomorphic irritation reaction (Kebner's symptom) is observed, which is expressed in the occurrence of psoriatic rashes at the sites of skin injury, sometimes even the most insignificant.

Over time, the formation of new papules and the peripheral growth of rashes stops, and the disease passes into the stationary stage. Evidence of growth arrest of the psoriatic element is the appearance of a pseudo-atrophic rim.

In some cases, an acute widespread rash occurs, the papules reach lenticular dimensions, and this is where the progression of the process ends (teardrop psoriasis). This course of psoriasis is usually associated with a streptococcal infection in the tonsils.

The resolution of psoriatic rashes often begins with the central part, which leads to the appearance of ring-shaped garland-shaped foci, as well as extensive foci of bizarre outlines - the stage of regression. After the rash resolves, hypopigmented spots remain in their place.

Psoriasis can affect any part of the skin, but more often it is localized on the extensor surface of the limbs, especially the elbow and knee joints, the scalp, in the sacrum. It is not uncommon for individual plaques, especially in the elbows and knees, to persist for a long time after the rest of the rash has resolved.

There are clinical varieties of ordinary psoriasis.

Seborrheic psoriasis occurs in patients with seborrhea with localization of rashes on the scalp, in the nasolabial folds, behind the auricles, in the chest area, in the skin folds. Rashes are poorly infiltrated and their boundaries are less clear than in the usual form; sebum-impregnated yellowish psoriatic scales are held on the surface, simulating a picture of seborrheic dermatitis.

Exudative psoriasis is caused by a pronounced exudative component of the inflammatory reaction, more often observed in people with increased body weight. Due to the penetration of exudate to the surface of the papules, the characteristic silvery-white appearance of the scales changes. They turn into grayish-yellowish, loose, moist cortical scales, tightly adhering to the surface of the skin.

Palmar-plantar psoriasis occurs more often in people of physical labor, which is explained by the traumatization of these areas of the skin. It may be accompanied by rashes in other areas of the skin, or it may be isolated. Clinically manifested either as ordinary psoriatic papules, or hyperkeratotic, simulating calluses. There is a continuous lesion of the skin of the palms and soles in the form of its thickening and increased keratinization.

Spotted psoriasis is characterized by mild infiltration of rashes that, after scraping off the scales, look like spots. It develops more often acutely, reminiscent of toxidermia.

Nail damage can develop in any clinical form of the disease in various ways, such as:

1) the formation of dotted depressions on the surface of the nail plates, resembling the working surface of a thimble, is due to foci of parakeratosis that form in the proximal part of the matrix;

2) changes in the type of oil stain (yellowish color of the nail bed, translucent through the nail plate) usually occurs in a progressive stage; due to histological changes in hyponychia, characteristic of psoriasis;

3) onycholysis is caused by subungual hyperkeratosis due to hyperproliferation of the epithelium of the nail bed. Clinically resembles onychomycosis;

4) leukonychia (white spots) occurs when the middle part of the matrix is affected.

Psoriasis can manifest itself in severe forms.

Psoriatic erythroderma develops in patients with widespread psoriasis in a progressive stage and is a nonspecific toxic-allergic reaction, most often provoked by various irritating factors (insolation, irrational external therapy). Initially, erythema appears on areas of the skin free from psoriatic rash, then merges, occupying the entire skin. The skin is bright red, swollen, infiltrated, lichenified in places, hot to the touch, covered with large and small dry white scales. Papules and plaques become indistinguishable. The general condition of patients is sharply disturbed, the temperature rises to 38-39 ° C, thermoregulation is disrupted, water-electrolyte imbalance and hypoproteinemia develop, which can lead to heart failure.

Pustular psoriasis is characterized by the eruption of sterile pustules. The morphological basis of the disease is the accumulation of neutrophils in the epidermis (Munro microabscesses). There are two forms of pustular psoriasis: generalized (Zumbusch type) and localized (limited), palmoplantar (Barber type).

Generalized pustular psoriasis (Zumbusch type) is characterized by an acute, subacute, or sometimes chronic eruption of sterile pustules. The disease develops against the background of typical psoriatic rashes. After the resolution of the pustules, the process usually takes on its original form.

The course of the disease is severe with fever, malaise, leukocytosis, elevated ESR. Paroxysmal against the background of bright erythema, small superficial pustules appear, accompanied by burning and soreness, located both in the area of plaques and on previously unchanged skin.

Localized pustular psoriasis (Barber type) is more common than the generalized form. One or more sharply defined plaques appear on the palms (in the thenar and hypothenar areas) and soles, within which there are numerous pustules with a diameter of 2-5 mm.

Psoriatic arthritis is one of the most severe forms of psoriasis, often leading to disability in patients. Articular involvement may develop in patients with pre-existing skin lesions simultaneously with, or precede, skin manifestations. In the future, synchronism in the development of relapses of skin lesions and arthritis may be observed.

The nature of skin rashes in psoriatic arthritis is distinguished by a number of features, in particular, a tendency to exudation, pustulization, resistance to therapy, the location of the rash in the terminal phalanges with nail damage up to onycholysis.

Treatment. Topical therapy is the use of non-irritating emollients in the form of ointment or cream after a bath or shower. Typically, emollient formulations contain low concentrations (1-2%) of salicylic acid or higher concentrations (5-6%) of lactic acid. This helps reduce peeling and restores the elasticity of the affected areas of the skin.

Topical corticosteroids have powerful anti-inflammatory, epidermostatic, anti-allergic and local anesthetic effects. They can be applied to the skin in the form of a cream (with progressive psoriasis, especially with a pronounced exudative component), ointment (with a stable lesion with severe infiltration), lotion (with localization of rashes on the scalp and face, especially with a tendency to seborrhea). If it is necessary to enhance the activity of these agents, occlusive dressings are used.

Synthetic retinoids act on the main pathogenetic links of the disease: they normalize impaired differentiation of keratinocytes, potentiate antiproliferative effects in the skin, and suppress the expression of inflammation markers.

Permissive means. Tar preparations have antimitotic, keratoplasty, anti-inflammatory, disinfectant and local irritant effects in high concentrations. Tar is used in various dosage forms (in the form of ointment, cream, lotion, paste, gel, shampoo), in various concentrations (from 1-2 to 30%, pure tar), as a single drug and in combinations with salicylic acid, dithranol and anthralin , topical corticosteroids.

Naftalan oil and its preparations, when exposed to the skin, have a softening, resolving, anti-inflammatory, disinfectant and some analgesic effect.

Hydroxianthrones. Dithranol, anthralin have a cytostatic and cytotoxic effect, which leads to a decrease in the activity of oxidative and glycolytic processes in epidermal cells, causing a decrease in the number of mitoses in the epidermis, parakeratosis and hyperkeratosis.

Systemic drug non-suppressive therapy. Hyposensitizing and detoxifying therapy. This group includes calcium preparations (citrate, gluconate, pantothenate), sodium thiosulfate, hemodez. Calcium preparations provide anti-inflammatory and hyposensitizing effects. Sodium thiosulfate has an anti-inflammatory, desensitizing effect. The drug is more active when administered intravenously. Hemodez is a water-salt solution containing low molecular weight polyvinylpyrrolidone, sodium, potassium, magnesium, chlorine ions. The mechanism of action of gemodez is due to the ability to bind toxins circulating in the blood and quickly remove them through the renal barrier.

Vitamin D3 has an active antiproliferative effect on the skin. It also normalizes the differentiation of epidermocytes, which together contributes to the resolution of psoriatic lesions.

Phototherapy. UV rays are used.

immunosuppressive therapy. Methotrexate. The action of methotrexate is based on the blockade of key steps in the biosynthesis of nucleic acids. The drug inhibits mainly DNA synthesis and cell reproduction and, to a lesser extent, RNA and protein synthesis. Used to correct excessive proliferation of epithelial cells.

Methotrexate is effective only when administered orally and parenterally. It is administered orally either in one dose once a week, or this dose is divided into three doses with an interval of 12 hours. The hepatotoxic effect is pronounced in the second variant of the drug.

Cyclosporine A is a selective immunosuppressive drug. The initial dose of cyclosporine A and sandimmune-neoral should be 2,5-3 mg per 1 kg of patient body weight per day. If clinical effect and optimal effectiveness are achieved after 4-8 weeks from the start of therapy, it is recommended to continue taking the drug at the same dose.

Glucocorticosteroids. The mechanism of action of glucocorticosteroid drugs in psoriasis is their powerful anti-inflammatory effect, active immunosuppressive effect, antitoxic effect.

The dose of glucocorticoids in most cases is 40-50 mg per day in terms of prednisolone. After achieving a positive clinical effect (not necessarily complete clinical regression), the drug is gradually withdrawn. The total duration of treatment with glucocorticosteroids is short (on average no more than 2-3 weeks).

Author: Sitkalieva E.V.

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