ICD-10-CM Code M33.2


Version 2020 Non-Billable Code

Not Valid for Submission

M33.2 is a "header" nonspecific and non-billable code code, consider using a code with a higher level of specificity for a diagnosis of polymyositis. The code is NOT valid for the year 2020 for the submission of HIPAA-covered transactions.

Short Description:Polymyositis
Long Description:Polymyositis

Consider the following ICD-10 codes with a higher level of specificity:

  • M33.20 - ... organ involvement unspecified
  • M33.21 - Polymyositis with respiratory involvement
  • M33.22 - Polymyositis with myopathy
  • M33.29 - Polymyositis with other organ involvement

Clinical Information

  • DERMATOMYOSITIS-. a subacute or chronic inflammatory disease of muscle and skin marked by proximal muscle weakness and a characteristic skin rash. the illness occurs with approximately equal frequency in children and adults. the skin lesions usually take the form of a purplish rash or less often an exfoliative dermatitis involving the nose cheeks forehead upper trunk and arms. the disease is associated with a complement mediated intramuscular microangiopathy leading to loss of capillaries muscle ischemia muscle fiber necrosis and perifascicular atrophy. the childhood form of this disease tends to evolve into a systemic vasculitis. dermatomyositis may occur in association with malignant neoplasms. from adams et al. principles of neurology 6th ed pp1405 6
  • POLYMYOSITIS-. diseases characterized by inflammation involving multiple muscles. this may occur as an acute or chronic condition associated with medication toxicity drug toxicity; connective tissue diseases; infections; malignant neoplasms; and other disorders. the term polymyositis is frequently used to refer to a specific clinical entity characterized by subacute or slowly progressing symmetrical weakness primarily affecting the proximal limb and trunk muscles. the illness may occur at any age but is most frequent in the fourth to sixth decade of life. weakness of pharyngeal and laryngeal muscles interstitial lung disease and inflammation of the myocardium may also occur. muscle biopsy reveals widespread destruction of segments of muscle fibers and an inflammatory cellular response. adams et al. principles of neurology 6th ed pp1404 9

Code Classification

  • Diseases of the musculoskeletal system and connective tissue (M00–M99)
    • Systemic connective tissue disorders (M30-M36)
      • Dermatopolymyositis (M33)

Code History

  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016
    (First year ICD-10-CM implemented into the HIPAA code set)
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020

Information for Patients


Myositis means inflammation of the muscles that you use to move your body. An injury, infection, or autoimmune disease can cause it. Two specific kinds are polymyositis and dermatomyositis. Polymyositis causes muscle weakness, usually in the muscles closest to the trunk of your body. Dermatomyositis causes muscle weakness, plus a skin rash.

Other symptoms of myositis may include

  • Fatigue after walking or standing
  • Tripping or falling
  • Trouble swallowing or breathing

Doctors may use a physical exam, lab tests, imaging tests and a muscle biopsy to diagnose myositis. There is no cure for these diseases, but you can treat the symptoms. Polymyositis and dermatomyositis are first treated with high doses of a corticosteroid. Other options include medications, physical therapy, exercise, heat therapy, assistive devices, and rest.

NIH: National Institute of Neurological Disorders and Stroke

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