The idiopathic inflammatory myopathies are systemic, chronic autoimmune diseases characterized by proximal symmetrical muscle weakness. One of the main diseases in this group is inclusion body myositis (IBM), an underdiagnosed, progressive muscle disease characteristically affecting the middle-aged and older population. It has a slow, relentlessly progressive course. The precise pathogenesis of the disease remains unknown. In most of the cases it is diagnosed a few years after the appearance of the first symptoms. The muscle biopsy typically shows endomysial inflammation, with invasion of mononuclear cells into the non-necrotic fibers, and also rimmed vacuoles. It appers, that both inflammation and degeneration are present at the onset of the disease. Our aim is to raise awareness about this disease which leads to severe disability, with clinicopathological case presentations and literature overview, emphasizing the importance of collaboration between the clinician and the neuropathologist. No effective therapy is currently available but the rapid diagnosis is essential to slow disease progression. Although this is a relatively rare disease, patients are presenting not only in immunology outpatient clinics; our reports aims to raise awareness and facilitate accurate early diagnosis of IBM.
