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The lecture considers the problem of rare systemic connective tissue diseases, such as idiopathic inflammatory myopathies (IIMs). It underlines the clinical and immunological heterogeneity of their subtypes, which defines therapeutic tactics and prognosis. The diagnostic criteria for IIMs are given. A differential diagnostic algorithm based on the exclusion of phenotypically similar forms of myopathies of different genesis is proposed.

Dermatomyositis (DM) and polymyositis (PM) belong to idiopathic inflammatory myopathies (IIM) and are characterized by inflammatory injury to the skeletal muscles. In DM, unlike PM, there is skin injury that serves as a pathognomonic sign of this condition. Panniculitis (PN) is one of the rare cutaneous manifestations in this disease.Objective: to investigate the clinical and laboratory characteristics of IIM accompanied by PN and to elaborate guidelines for managing these patients.Subjects and methods. Examinations were made in 318 patients (75 men and 243 women) aged 18 to 80 years who were diagnosed with IIM (mean disease duration of 18.97±7.4 months) and followed up at the V.A. Nasonova Research Institute of Rheumatology in 1996 to 2015.Results and discussion. In 12 (3.8%) of the 318 patients, lobular PN that was associated with the diagnosis of DM verified in all cases. The clinical picture in this patient group was also characterized by skin injury as erythema on the face and trunk and Gottron’s papules (100%), periungual capillaritis (91.7%), ulceronecrotic vasculitis (57.3%), periorbital edema (75%), fever (41.7%), alopecia (50%), and joint involvement (25%).Conclusion. The development of PN is associated with the acute period of DM and the emergence of new foci is related to an exacerbation of this disease, which requires active therapy.

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of acquired systemic diseases mainly involving skeletal muscles. The main representatives of IIM are polymyositis (PM) and dermatomyositis (DM). Epidemiological surveys demonstrate that there is a relationship between PM/DM and malignant neoplasms (MNs), the detection risk of which is higher than that in the population of respective age groups. The rate of MNs in PM/DM ranges from 9 to 50%. The relationship to MNs is described in each subtype of IIM; however, these are most common in DM. The patients suffering from PM/DM associated with MNs have a worse prognosis than those without MNs. The early detection of MNs could improve the prognosis in these patients. The investigations published identify demographic, clinical, and laboratory factors increasing MN detection risks in patients with PM/DM. Just the same, they all cover small patient groups; the findings are heterogeneous and not well convincing, which calls for a further larger-scale study of this problem.Objective: to reveal and identify the specific features of paraneoplastic myositis (PnM).Subjects and methods. The investigation included 320 patients with a valid diagnosis of IIM, who had been followed up in the period of 1996 to 2016. The patients underwent laboratory tests, manual proximal muscle strength testing using a 10-point scale and electromyographic examination with needle electrodes.Results and discussion. PnM was detected in 32 (10%) of the 320 patients with IIM. Among the patients with PnM, there were 6 (19%) men and 26 (81%) women. The mean age at the onset of PnM was 55.4 years. PnM manifested with characteristic musculocutaneous syndrome in 19 (59%) patients; 18 (41%) of them were found to have MNs within the first year after disease onset. The manifestation of MNs was preliminary to the picture of PM/DM in 13 (41%) patients. The most commonly detected conditions were ovarian cancer (37.5%), MNs of the lung and breast (15%); next were MNs of the intestine (12.5%), blood (6.3%), uterus (6%), and stomach (3.1%). The median survival was 5 years in patients with PnM.

The paper deals with the problems of optimizing the diagnostic criteria for idiopathic inflammatory myopathies (IIM), a group of heterogeneous rare autoimmune diseases characterized by inflammatory lesion in the skeletal muscles. The representatives of this group are traditionally considered to be polymyositis (PM), dermatomyositis (DM), and inclusion-body myositis. The authors detail the history of classification criteria for IIM from those proposed by T.A. Medsger et al. (1970) relying on its clinical picture, laboratory data and instrumental findings, as well as the criteria (including the first introduced exclusion ones) elaborated by A. Bohan and J.B. Peter in 1975, which remain fundamental in both clinical practice and researches. The basis for the clinical and serological criteria proposed by Y. Troyanov et al. (2005) for IIM is the identification of myositis-overlap syndromes. The classificational (subtype identification) and therapeutic value of the criteria based on clinical and serological characteristics was supported by the Hungarian investigators A. Vancsa et al. (2010) who investigated the relationship between the clinical and therapeutic characteristics of IIM and positivity for myositis-specific and myositis-associated antibodies. The criteria developed by M.C. Dalakas (1991, 2003) are based on the specific immunopathological features of a histological pattern, which allow the differentiation of DM, PM, and inclusion-body myositis from other myopathic syndromes. The 2004 European Neuromuscular Center (ENMC) criteria first identify necrotizing autoimmune myopathy and nonspecific myositis as individual subtypes. The serological classification of IIM, which is based onthe assessment of autoantibodies that play an important role in the pathogenesis of the disease, is of indubitable interest. There is an obvious need for the correct and timely diagnosis of both IIM as a whole and its subtypes in particular, which is complicated by theheterogeneity of the latter. The proposed approaches to diagnosing and classifying IIM have their advantages and disadvantages so that work in this direction is yet to be under way.