Dermatomyositis
Dermatomyositis is a diffuse inflammatory pathology of connective tissue with a progressive course, characterized by damage to smooth and striated muscle fibers with impaired motor functions, skin involvement, small vessels and internal organs. In the absence of a skin syndrome, the presence of polymyositis is indicated. The clinic of dermatomyositis is characterized by polyarthralgia, severe muscle weakness, fever, erythematous-spotted rash, skin calcifications, visceral symptoms. Diagnostic criteria for dermatomyositis are clinical, biochemical, and electromyographic indicators. The main therapy is hormonal, the course of dermatomyositis is undulating.
General information
Dermatomyositis is a diffuse inflammatory pathology of connective tissue with a progressive course, characterized by damage to smooth and striated muscle fibers with impaired motor functions, skin involvement, small vessels and internal organs. In the absence of a skin syndrome, the presence of polymyositis is indicated. The clinic of dermatomyositis is characterized by polyarthralgia, severe muscle weakness, fever, erythematous-spotted rash, skin calcifications, visceral symptoms. Diagnostic criteria for dermatomyositis are clinical, biochemical, and electromyographic indicators. The main therapy is hormonal, the course of dermatomyositis is undulating.
The etiological connection of dermatomyositis with viral infection (picornaviruses, Coxsackie viruses) and genetic conditioning is assumed. The chronic persistence of viruses in muscles and the antigenic similarity between viral and muscle structures causes an immune response with the formation of autoantibodies to muscle tissue. Hypothermia, infectious exacerbation, stress, hyperthermia, hyperinsolation, drug provocation (vaccination, allergy) can serve as triggers for the development of dermatomyositis.
Classification of dermatomyositis
Dermatomyositis and polymyositis belong to the group of idiopathic inflammatory myopathies. Secondary paraneoplastic (tumor) dermatomyositis occurs in 20-30% of cases. The course of dermatomyositis can be acute, subacute or chronic.
In the development of pathology, there is a period of nonspecific precursors (prodromal), clinical manifestations (manifest) and a stage of complications (terminal, dystrophic, cachectic). Dermatomyositis can occur with varying degrees of inflammatory activity (from I to III).
Symptoms of dermatomyositis
The clinic of dermatomyositis develops gradually. At the beginning of the disease, progressive weakness in the muscles of the extremities is noted, which can increase over the years. The acute onset is less characteristic of dermatomyositis. The main clinical manifestations may be preceded by the appearance of skin rashes, polyarthralgia, Raynaud’s syndrome.
The defining symptom in the clinic of dermatomyositis is a lesion of striated musculature. Weakness in the neck muscles, proximal parts of the lower and upper extremities is characteristic, leading to difficulty in performing everyday actions. With severe lesions, patients hardly get up in bed, cannot hold their heads, move independently and hold objects in their hands.
Involvement of the muscles of the pharynx and upper digestive tract is manifested by speech disorders, swallowing disorders, choking; damage to the diaphragm and intercostal muscles is accompanied by a violation of lung ventilation, the development of congestive pneumonia. A characteristic feature of dermatomyositis is a skin lesion with various manifestations. The development of periorbital edema, erythematous-spotted rash over the upper eyelids, in the area of cheekbones, nasolabial folds, nose wings, upper back, sternum, joints (knee, elbow, metacarpophalangeal, interphalangeal) is noted.
Typically, the presence of a Gottron symptom is flaky erythematous spots on the skin of the fingers, peeling and redness of the palms, brittle and striated nails, periarticular erythema. A classic sign of dermatomyositis is the alternation of foci of depigmentation and pigmentation on the skin in combination with telangiectasia, dryness, hyperkeratosis and atrophy of skin areas (poikilodermatomyositis).
On the part of the mucous membranes with dermatomyositis, the phenomena of conjunctivitis, stomatitis, edema and hyperemia of the palate and posterior pharyngeal wall are noted. Sometimes there is an articular syndrome with lesions of the knee, ankle, shoulder, elbow, wrist joints, small joints of the hands. With juvenile dermatomyositis, intradermal, intrafacial and intramuscular calcifications may appear in the projection of the pelvic, shoulder girdle, buttocks, joints. Subcutaneous calcinates can lead to ulceration of the skin and the release of calcium deposits outside in the form of a crumbly mass.
Among the systemic manifestations of dermatomyositis, there are lesions of the heart (myocardiofibrosis, myocarditis, pericarditis); lungs (interstitial pneumonia, fibrosing alveolitis, pneumosclerosis); gastrointestinal tract (dysphagia, hepatomegaly); kidneys (glomerulonephritis), nervous system (polyneuritis), endocrine glands (hypofunction of the adrenal glands and gonads).
Diagnosis of dermatomyositis
The main diagnostic markers of dermatomyositis are characteristic clinical manifestations of skin and musculature lesions; pathomorphological transformation of muscle fibers; increased serum enzyme levels; typical electromyographic changes. Additional (auxiliary) criteria for the diagnosis of dermatomyositis include dysphagia and calcinosis.
The reliability of the diagnosis of dermatomyositis is beyond doubt in the presence of 3 main diagnostic criteria and skin rash or 2 main, 2 auxiliary criteria and skin manifestations. The probability of dermatomyositis cannot be excluded when skin lesions are detected; with a combination of any 2 other main manifestations, as well as with a combination of any main and 2 auxiliary criteria. To establish the fact of polymyositis, it is necessary to have 4 diagnostic criteria.
The blood picture is characterized by moderate anemia, leukocytosis, neutrophilic shift of the leukocyte formula to the left, an increase in ESR in accordance with the activity of the process. Biochemical markers of dermatomyositis are an increase in the level of α2- and γ-globulins, fibrinogen, myoglobin, sialic acids, haptoglobin, seromucoid, transaminases, aldolase, reflecting the severity of muscle tissue damage. Immunological examination of blood in dermatomyositis reveals a reduced complement range, a decrease in the number of T-lymphocytes, an increase in the level of IgG and IgM immunoglobulins with a decrease in IgA, an insignificant number of LE cells and antibodies to DNA, a high content of myositis-specific antibodies, the presence of nonspecific antibodies to thyroglobulin, myosin, endothelium, etc.
When examining skin and muscle biopsies, the picture of severe myositis, fibrosis, degeneration, inflammatory infiltration of muscle fibers, loss of transverse striation is determined. An electromyogram for dermatomyositis records increased muscle excitability, short-wave polyphase changes, and fibrillar oscillations at rest. Soft tissue radiographs show areas of calcification; lung radiography determines an increase in the size of the heart, pleural calcifications, interstitial fibrosis of the lung tissue. Moderate osteoporosis is detected in the bones.
Treatment of dermatomyositis
If the respiratory muscles and palatine muscles are affected, it is necessary to ensure the functions of adequate breathing and swallowing. Corticosteroids (prednisone) are used to suppress inflammatory phenomena in dermatomyositis under the control of serum blood enzymes and the clinical condition of the patient. During treatment, the optimal dosage of corticosteroids is selected, the drugs are taken for a long time (1-2 years). It is possible to conduct steroid pulse therapy. The anti-inflammatory regimen for dermatomyositis can be supplemented with the appointment of salicylates.
In case of ineffectiveness of corticosteroid therapy for dermatomyositis, cytostatic immunosuppressants (methotrexate, cyclosporine, azathioprine) are prescribed. To control the skin manifestations of dermatomyositis, derivatives of 4-aminoquinoline (hydroxychloroquine) are used; injections of neostigmine, ATP, cocarboxylase, and B vitamins are used to normalize muscle functions. In the treatment of dermatomyositis, intravenous administration of immunoglobulin, sessions of lymphocytapheresis and plasmapheresis are used. In order to prevent muscle contractures, a complex of exercise therapy is prescribed.
Prognosis and prevention of dermatomyositis
With the advanced course of dermatomyositis, mortality in the first 2 years of the disease development reaches 40%, mainly due to damage to the respiratory muscles and gastrointestinal bleeding. With severe prolonged dermatomyositis, contractures and deformities of the limbs develop, leading to disability. Timely intensive corticosteroid therapy suppresses the activity of the disease and significantly improves the long-term prognosis.
Measures to prevent the development of dermatomyositis have not been developed. Measures of secondary prevention of dermatomyositis include dispensary control of a rheumatologist, supportive therapy with corticosteroids, reduction of reactive hypersensitivity of the body, sanitization of focal infection.
