Cutaneous manifestations in dermatomyositis

Dermatomyositis (synonym: polymyositis, Wagner's disease) is a connective tissue disease that occurs with predominant damage to the skin and skeletal muscles, a severe disease of unclear etiology, characterized by dystrophic changes, mainly striated muscle tissue, and skin manifestations. There are cases that occur only with muscle damage. In the pathogenesis of the disease, the main significance is given to cell-mediated sensitization to various antigens. It develops at any age, including in children, but mainly after 50 years, more often in women.

Causes and pathogenesis of dermatomyositis

There are several theories (infectious, viral, autoimmune) that explain the development of dermatomyositis. Currently, many dermatologists support the autoimmune hypothesis of dermatomyositis development, as evidenced by the systemic nature, sensitization of lymphocytes to antigens. muscle tissue, cytotoxicity of lymphocytes to cultures of auto-, homo- and heterologic muscle, the presence of antinuclear antibodies, circulating immune complexes. The presence of familial cases, the development of the disease in twins, other connective tissue diseases in families, associations with antigens and histocompatibility (HLA D8 and DRW3) allowed scientists to put forward a theory about the genetic predisposition of the disease.

There is paraneoplastic dermatomyositis. The nature of the association of dermatomyositis with tumors has not been established. It is believed that the allergenic effect of tumor products on the body and the inclusion of immune mechanisms are possible. Diseases of the internal organs, nervous and endocrine systems play an important role in the development of dermatomyositis. Scleroatrophic lichen can be provoked by drugs, infectious diseases, insolation, etc.

Symptoms of dermatomyositis

Dermatomyositis is divided into primary (idiopathic), which most often develops in children, and secondary (usually paraneoplastic), which is observed mainly in adults, and according to the course - into acute, subacute and chronic.

Among skin manifestations, the most characteristic is edematous erythema with a lilac tint, located mainly on exposed parts of the body, especially on the face, especially periorbitally, and on the back of the hands, neck, upper chest and back. Scleroderma-like changes may be observed on the forearms and back of the hands. Sometimes the rash is polymorphic, which makes the clinical picture similar to systemic lupus erythematosus, especially when antinuclear antibodies and deposits of immune complexes under the basement membrane of the epidermis are detected. With a long course of the disease, atrophic changes in the skin with poikiloderma (poikilodermatomyositis) develop. The muscles of the shoulder and pelvic girdle are most often affected. Pain, swelling, weakness, atrophy, progressive hypotension, and adynamia are noted. When the muscles of the esophagus are affected, swallowing is difficult; when the muscles of the diaphragm are involved in the process, breathing is impaired.

The disease is often observed in women. In most patients, the disease begins with prodromal symptoms. In some patients, the process develops slowly with minor pain in the limbs, malaise and a slight increase in temperature. But an acute onset of the disease is also possible (severe pain, especially in the limbs, headache, dizziness, nausea and vomiting, severe chills with a high temperature). Most patients experience swelling and redness of the face with a purple tint, especially in the periorbital area. Erythema is especially pronounced on the upper eyelids and around them (the "glasses" symptom). Sometimes it occupies the middle part of the face, then resembling the "butterfly" of lupus erythematosus. The presence of multiple telangiectasias makes the color more saturated.

Erythema and swelling are usually also observed on the lateral surfaces of the neck, to a lesser extent on the extensor surfaces of the upper limbs, trunk, and sometimes on some other areas. On the limbs, the skin is affected mainly in the area of large muscles and joints. Erythema and swelling can spread from the neck to the shoulders, chest, and back like a cape. Relatively rarely, nodular lichenoid rashes appear against the background of redness or outside of it. Urticarial, vesicular, bullous, papular, and hemorrhagic rashes sometimes appear against the background of erythema. There are reports of cases of necrotic changes, erosions, and ulcerations of the skin. In some patients, dermatomyositis takes on the character of erythroderma (Milian's "myasthenic erythroderma"). Scleroderma-like changes may appear on the hands and forearms. In these areas, the skin is dry, hair loss and nail damage are observed. Later, the clinical picture of poikiloderma may develop. Approximately 25% of all patients with dermatomyositis have lesions of the mucous membranes in the form of stomatitis, glossitis, conjunctivitis, and leukoplakia of the tongue.

Subjective symptoms are usually expressed very sharply, but patients almost never complain of itching, only in some cases it is intense.

Along with the skin, dermatomyositis, as the name of the disease suggests, affects the muscular system, which usually manifests itself at the very beginning. Patients are bothered by progressive muscle weakness, mainly in the proximal parts of the limbs, adynamia. Any muscle can be involved in the process. Patients complain of more or less severe pain, with passive extension of the limbs being especially painful. Due to damage to the skeletal muscles, the gait becomes unsteady, it is impossible to hold the head straight, it is difficult to take off clothes ("shirt symptom"), climb stairs ("stairs symptom"), comb hair ("comb symptom"). A tearful expression is striking, which is the result of damage to the facial muscles. The face looks heavily furrowed ("carnival mask"), sad ("tearful mood").

When the pharyngeal muscles are affected, patients easily choke; when the laryngeal muscles are affected, aphonia develops. Over time, the muscles atrophy, calcium salts are deposited in them, and contractures develop. In some patients, rhmatomyositis is clinically manifested only by muscle changes ("polymyositis").

Dermatomyositis also causes visceral lesions - gastrointestinal tract, upper respiratory tract, bronchi and lungs, myocardium and endocardium, involvement of the central and peripheral nervous system, tropical disorders of skin appendages, osteoporosis. Common symptoms often include tachycardia, severe hyperhidrosis, significant weight loss, and increased sensitivity to light.

Usually, an accelerated ESR is detected, often creatinuria, albuminuria, and the amount of serum albumin is reduced.

Dermatomyositis is relatively often combined with malignant tumors of internal organs (cancer, much less often - other tumors: sarcoma, leukemia, cervical cancer, etc.).

Removal of the malignant tumor leads to rapid clinical improvement and sometimes even complete remission of dermatomyositis.

Histopathology of dermatomyositis

Changes in the epidermis and dermis resemble those in scleroderma, and partly in lupus erythematosus. Deep muscle biopsy does not reveal transverse striation. Fragmentation, various types of muscle fiber dystrophy, and infiltrates in the interstitium, perivascular or diffuse, mainly from lymphoid cells, are detected.

Pathomorphology of dermatomyositis

In the skin, the picture may vary depending on the intensity of the process. In the initial stages, weakly expressed perivascular infiltrates of a lymphohistiocytic nature and capillaritis are observed. Later, atrophy of the epidermis with vacuolar degeneration of the cells of the basal layer, edema of the upper part of the dermis, an inflammatory reaction develop, often with fibrinoid changes around the capillaries and in the area of the dermoepidermal junction. In old lesions, phenomena of vascular poikiloderma are observed, in which a strip-like infiltrate of lymphocytes and histiocytes is found under the epidermis. The epidermis is atrophic, epidermal outgrowths are smoothed out, foci of mucinous degeneration in the dermis can often be seen in the form of deposition of glycosaminoglycans, more often in places of inflammatory infiltrates. Foci of mucinous degeneration are also found in the subcutaneous tissue. In later stages of the process, calcium salt deposits may be observed.

In the affected muscles, dystrophic and destructive changes prevail, the degree of which depends on the severity of the process, which is expressed in the disappearance of transverse striation, hyalinosis of the sarcoplasm with proliferation of its nuclei. Sometimes muscle fibers become structureless, disintegrate into separate fragments, which are then subject to phagocytosis. In the interstitium, inflammatory infiltrates of varying degrees are found, consisting of lymphocytes, plasma cells, histiocytes and fibroblasts. In cases of the most pronounced destructive changes in muscle fibers (infarction), the inflammatory reaction intensifies. In this case, the infiltrate cells are located between the affected muscle fibers and around the vessels in the form of significant clusters. Sometimes, histochemical methods reveal only dystrophic and necrobiotic changes in muscle fibers with a sharp decrease and disappearance of the activity of oxidative metabolism enzymes and muscle contraction. In old lesions, atrophy of the remaining muscle fibers is observed, surrounded by fibrous tissue that covers the dead fibers. The interstitial vessels are also involved in the inflammatory process; in the acute period, edema of the walls and proliferation of enloteliocytes are detected in them. Sometimes thrombovasculitis. In later stages, sclerosis of the walls with obliteration of the lumens is observed,

The histogenesis of dermatomyositis is unclear. Some authors classify it as an autoimmune disease, while others consider dermatomyositis (the result of sensitization of the body to various antigens: infectious, bacterial, viral, etc.) Undoubtedly, humoral and cellular factors of immunity participate in the development of the inflammatory reaction. It is assumed that humoral immune factors cause damage to the vessels of the microcirculatory bed with subsequent development of dystrophic and necrobiotic changes in muscle fibers. Disturbances in the cellular link of immunity are evidenced by the aggregation of activated mononuclear leukocytes in skeletal muscles, which in culture have a cytotoxic effect directed against muscle cells, and are also capable of lymphoblastic transformation. Almost half of patients with dermatomyositis have autoantibodies. The production of antibodies against myosin and myoglobin, which were previously given great importance, is most likely the result of necrosis of skeletal mice. More likely, although not proven, is the pathogenetic role heterogeneous group of angiocyte antibodies, such as PM-1 (PM-Scl). Kn, PA-1, Mi-2. In the reaction of direct immunofluorescence and in 35% of cases in the lesions of the skin, granular deposits of immunoglobulins (IgG, IgM, IgA) and complement are detected in the zone of the dermal-epidermal border. In inflammatory infiltrates in the dermis, activated T-helper lymphocytes and macrophages with an admixture of single Langerhans cells predominate.

There is a certain genetic predisposition to the development of dermatomyositis - an association with the antigens of the HLA-B8 and HLA-DR3 systems has been discovered, and family cases of the disease have been described.

K. Hashimoto et al. (1971) found virus-like particles on affected muscle fibers using electron microscopy. There is evidence of a connection between dermatomyositis and toxoplasmosis. A syndrome similar to dermatomyositis is observed in recessively inherited X-linked hypogammaglobulinemia; muscle damage may occur in drug-induced pathology caused by L-tryptophan, the so-called "eosinophilia-myalgia" syndrome.

Differential diagnosis

The disease should be differentiated from lupus erythematosus, scleroderma, and spontaneous panniculitis.

Treatment of dermatomyositis

Glucocorticosteroids are prescribed at a dose of 0.5-1 mg/kg/day. If ineffective, the dose is increased to 1.5 mg/day.

A good effect is noted with a combination of prednisolone and azothioprine (2-5 mg/kg/day orally). It is necessary to avoid steroid myopathy, which often develops 4-6 weeks after the start of treatment. Positive results are given by immunosuppressants - methotrexate and cyclophosphamide. There are reports on the effectiveness of intravenous injections of immunoglobulin in high doses (0.4 g/kg/day for 5 days) as monotherapy and in combination with corticosteroids.

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