Inflammatory Myopathies: Diagnostic Challenges and Management Approaches for the Internal Medicine Physician in Inclusion Body Myositis, Polymyositis, and Dermatomyositis

Inclusion Body Myositis (IBM), Polymyositis (PM), and Dermatomyositis (DM) are distinct autoimmune-mediated inflammatory myopathies that primarily affect skeletal muscles but differ in their clinical presentation, pathophysiology, and management.IBM is most commonly seen in older individuals and is characterized by asymmetric, progressive muscle weakness, particularly in the distal arm and proximal leg muscles.It is also resistant to immunosuppressive treatments.In contrast, PM and DM exhibit symmetric proximal muscle weakness, with DM additionally presenting distinctive dermatological manifestations such as heliotrope rashes and Gottron's papules.Both PM and DM are associated with extra muscular complications, including interstitial lung disease and, in DM, increased cancer risk, particularly in older adults.Diagnostic evaluation relies on clinical assessment, elevated muscle enzymes, electromyography, and muscle biopsy, with distinct histological features guiding diagnosis.While IBM may present with rimmed vacuoles and protein aggregates, PM and DM show endomysial lymphocytic infiltration and vasculopathy.Treatment strategies for PM and DM involve glucocorticoids combined with disease-modifying antirheumatic drugs (DMARDs), with additional therapies like intravenous immunoglobulin (IVIG) and rituximab in refractory cases.IBM management focuses on supportive care, physical therapy, and addressing comorbidities.Despite progress in understanding these disorders, therapeutic options remain limited, especially for IBM.Early diagnosis, individualized treatment, and ongoing research into biomarkers and targeted therapies are essential for improving patient outcomes and quality of life in these challenging conditions.