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Not to be confused with poliomyelitis.
Polymyositis HE.jpg
Classification and external resources
Specialty Rheumatology
ICD-10 M33.2
ICD-9-CM 710.4
DiseasesDB 10343
MedlinePlus 000428
eMedicine med/3441 emerg/474
MeSH D017285

Polymyositis (PM)("inflammation of many muscles") is a type of chronic inflammation of the muscles (inflammatory myopathy) related to dermatomyositis and inclusion body myositis.

Signs and symptoms[edit]

Symptoms include pain, with marked weakness and/or loss of muscle mass in the muscles of the head, neck, torso and upper arms and legs. The hip extensors are often severely affected, leading to particular difficulty in ascending stairs and rising from a seated position. Dysphagia (difficulty swallowing) or other problems with esophageal motility occur in as many as 1/3 of patients. Low grade fever and peripheral adenopathy may be present. Foot drop in one or both feet can be a symptom of advanced polymyositis and inclusion body myositis. Polymyositis is also associated with interstitial lung disease.

Polymyositis may represent a modest increased risk for non-Hodgkin lymphoma and lung and bladder cancers.[1]

Polymyositis tends to become evident in adulthood, presenting with bilateral proximal muscle weakness often noted in the upper legs due to early fatigue while walking. Sometimes the weakness presents itself as an inability to rise from a seated position without help or an inability to raise one's arms above one's head. The weakness is generally progressive, accompanied by lymphocytic inflammation (mainly cytotoxic T cells).

Polymyositis, like dermatomyositis, strikes females with greater frequency than males. The skin involvement of dermatomyositis is absent in polymyositis.


The cause of polymyositis is unknown and may involve viruses and autoimmune factors. Cancer may trigger polymyositis and dermatomyositis, possibly through an immune reaction against cancer that also attacks a component of muscles.[2]


Diagnosis is fourfold, including elevation of creatine kinase, history and physical examination, electromyograph (EMG) alteration, and a positive muscle biopsy.

Sporadic inclusion body myositis (sIBM): IBM is often confused with (misdiagnosed as) polymyositis or dermatomyositis that does not respond to treatment is likely IBM. sIBM comes on over months to years; polymyositis comes on over weeks to months. Polymyositis tends to respond well to treatment, at least initially; IBM does not.


The first line treatment for polymyositis is corticosteroids. Specialized exercise therapy may supplement treatment to enhance quality of life.

Notable cases[edit]

  • Dan Christensen, painter of abstract art. Died due to heart failure caused by polymyositis.[3]
  • Robert Erickson, American composer and teacher who was a leading modernist exponent of "12-tone" composition. Died from the effects of polymyositis.[4]
  • David Lean, film director.[5][6]

See also[edit]


  1. ^ Hill, C.L.; Zhang, Y.; Sigurgeirsson, B.; Pukkala, E.; Mellemkjaer, L.; Airio, A.; Evans, S.R.; Felson, D.T. (January 2001). "Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study". Lancet 357 (9250): 96–100. doi:10.1016/S0140-6736(00)03540-6. PMID 11197446. Retrieved 20 April 2015. 
  2. ^ Hajj-ali, Rula A. (August 2013). "Polymyositis and Dermatomyositis". Merck Manual Home Edition. Retrieved 20 April 2015. 
  3. ^ "Dan Christensen, 64, Painter of Abstract Art, Dies". The New York Times. 27 January 2007. Retrieved 20 April 2015. 
  4. ^ "Obutiary - Robert Erickson". SF Gate. 29 April 1997. Retrieved 20 April 2015. 
  5. ^ Stevens, Jr., George (2006). Conversations with the Great Moviemakers of Hollywood's Golden Age at the American Film Institute. Knopf. p. 427. ISBN 978-1-4000-4054-4. 
  6. ^ Brownlow, Kevin (1996). David Lean: A Biography. Macmillan. pp. 1466–1467. ISBN 978-1-4668-3237-4. Retrieved 20 April 2015. 

External links[edit]