UMMS Affiliation

Department of Medicine, Division of Rheumatology

Publication Date


Document Type

Book Chapter


Diagnosis | Immune System Diseases | Musculoskeletal Diseases | Nervous System Diseases


Inclusion body myositis (IBM) is the most common subtype of autoimmune myopathy in patients older than the age of 50 years. Several diagnostic criteria have been proposed for IBM based on expert opinion and consensus groups. Their use in clinical practice is however limited due to low sensitivity. The European Neuromuscular Centre (ENMC) 2011 clinically defined diagnostic criteria have a high specificity of greater than 99% to diagnose IBM, but like other criteria, its sensitivity is low at 57%. ENMC 2011 Inclusion Body Myositis Diagnostic Criteria Mandatory Features: 1. Age of onset later than 45 years. 2. Duration of symptoms more than 12 months. 3. Serum creatine kinase level, not more than 15 times the upper limit of normal. Clinical Features: 1. A weakness of quadriceps more than hip flexors. 2. A weakness of finger flexors more than shoulder abductors. Pathological Features: 1. Endomysial inflammatory infiltrate. 2. Rimmed vacuoles. 3. Protein accumulation or 15- to 18-nm filaments. 4. Upregulation of MHC class I. Classification Criteria: Clinicopathologically defined IBM: Mandatory criteria + one or both of the clinical criteria plus 1, 2, and 3 of the pathological criteria Clinically defined IBM: Mandatory criteria plus all clinical criteria plus one or more, but not all the pathological criteria Probable IBM: Mandatory criteria plus one clinical criterion plus one or more, but not all the pathological criteria.


Inclusion body myositis

Rights and Permissions

Copyright © 2019, StatPearls Publishing LLC. This book is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, a link is provided to the Creative Commons license, and any changes made are indicated.


Panginikkod S, Musa R. Inclusion Body Myositis. 2019 Feb 15. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from PubMed PMID: 30855788.

Journal/Book/Conference Title



Last Update: April 23, 2019.

Access free multiple choice questions on this topic

Related Resources

Link to Article in PubMed

PubMed ID


Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.