How is inclusion body myositis (IBM) diagnosed?

Doctors use a muscle biopsy to diagnose IBM. After giving an anesthetic, a doctor takes a sample of tissue from one of the affected muscles to be looked at in a laboratory.

When viewed under the microscope, the muscle cells of persons with IBM contain vacuoles (rounded empty spaces). Within the vacuoles, there are usually abnormal clumps of several proteins including one called amyloid. The protein clumps, or inclusion bodies, give IBM its name. This is the hallmark of IBM.

Last reviewed by a Cleveland Clinic medical professional on 04/02/2019.


  • Ropper AH, Samuels MA, Klein JP. Chapter 48. Diseases of Muscle. In: Ropper AH, Samuels MA, Klein JP. eds. Adams & Victor's Principles of Neurology, 10e. New York, NY: McGraw-Hill; 2014.
  • Dalakas MC. Chapter 388. Polymyositis, Dermatomyositis, and Inclusion Body Myositis. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 18e. New York, NY: McGraw-Hill; 2012.
  • World Gastroenterology Organisation Practice Guidelines. Dysphagia. Accessed 4/3/2019.
  • Genetic and Rare Diseases Information Center. Inclusion body myositis. Accessed 4/3/2019.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy