Clinical Findings, Antibody Panel and Pathology of Patients with Inflammatory Myopathies in Isfahan Province, Iran

In the current study, we aimed to evaluate the characteristics of individuals with autoimmune inflammatory myopathies (AIMs) in Isfahan.

In this retrospective, observational study, the clinical, histopathological, immunohistochemical staining, electromyography, and autoantibody profile of the patients with AIM in subgroups of dermatomyositis (DM), necrotizing autoimmune myopathy (NAM), polymyositis (PM), and antisynthetase syndrome (AS) were assessed.

Seventy-seven patients with AIMs including 38 (49.3%), 21 (27.3%), 14 (18.2%), and 4 (5.2%) with NAM, DM, PM, and antisynthetase diagnoses were enrolled, respectively. Proximal weakness (94.80%), myalgia (32.46%), skin rash (25.97%), and dysphagia (25.97%) were the most common presentations, among which skin rash was statistically more frequent in DM (P value = 0.001). Fiber necrosis (100%), CD68 (92.1%), and C5-b9 (60.5%) positivity, irritable myopathy (78.9%), and anti-Ro-52 (7.1%) positivity were the most common findings in NAM. Perivascular infiltration (71.4%), fiber degeneration (66.7%) and necrosis (52.4%), CD68 (100%), CD20 (71.4%), and CD8 (71.4%), both irritable (57.1%) and non-irritable (38.1%) myopathy, anti-Mi-2 (19%), anti-NXP-2 (19%), and anti-MDA-5 (14.3%) autoantibodies were the detected characteristics of DM patients. PM individuals were characterized with endomysial infiltration (92.9%), fiber necrosis (71.4%) and perivascular infiltration (64.3%), CD68 (100%), CD20 (100%) and CD8 (92.9%) positivity, both irritable (57.1%) and non-irritable (42.9%) myopathy and anti-Mi-2 (14.3%), and anti-ANA (14.3%) antibodies. Fiber necrosis (100%) and degeneration (75%), CD68 (75%), CD8 (75%), and C5-b9 (75%), irritable myopathy (50%), and anti-Jo-1 antibody (100%) positivity were the diagnostic tools for AS.

According to the outcomes of the current study, the clinical, histopathological, and autoantibody profiles of the patients with AIM are variably different with remarkable overlaps. Therefore, thorough assessments are required to make the final diagnosis.