inclusion body myositis
Progressive inflammatory myopathy characterized by weakness of distal and proximal muscles with distinctive pathological inclusions.
Full Definition
Inclusion body myositis (IBM) is the most common inflammatory myopathy in patients over 50 years, characterized by progressive weakness affecting both proximal and distal muscles, particularly finger flexors and knee extensors. The condition presents with asymmetric muscle weakness, often involving swallowing difficulties and falls. Pathologically, muscle biopsy reveals inflammatory infiltrates, rimmed vacuoles, and characteristic protein inclusions containing amyloid and tau. Unlike other inflammatory myopathies, IBM typically responds poorly to immunosuppressive therapy. Diagnosis requires correlation of clinical presentation, electrophysiological findings, elevated muscle enzymes, and distinctive pathological features. The prognosis is generally poor with progressive disability over years.
Usage
Usage note: IBM abbreviation acceptable after first use; distinguish from inflammatory bowel disease IBM.
In Context
- "The muscle biopsy confirmed inclusion body myositis with characteristic rimmed vacuoles and protein aggregates." — Pathology report
- "Unlike other inflammatory myopathies, inclusion body myositis shows poor response to corticosteroid therapy." — Treatment review