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  2. ICD-10-CM Codes List
  3. M00–M99
  4. M30-M36
  5. Dermatopolymyositis (M33)

Dermatopolymyositis (M33)

The ICD-10 code for dermatopolymyositis (M33) covers a group of rare inflammatory diseases affecting the skin and muscles. These codes are used to classify various forms, such as juvenile and adult dermatomyositis, polymyositis, and their complications involving muscles, lungs, or other organs.

This section helps medical coders accurately identify specific types of dermatopolymyositis, including juvenile dermatomyositis (M33.0) and other dermatomyositis (M33.1), which have subcodes differentiating between organ involvement like respiratory issues or myopathy. Synonyms like childhood type dermatomyositis, overlap syndrome, and connective tissue disease overlap syndrome guide coders to the appropriate code. Similarly, polymyositis (M33.2) codes account for cases with or without organ involvement, using terms such as idiopathic polymyositis or antisynthetase syndrome. The unspecified codes (M33.9 and variations) cover cases where detailed organ involvement isn’t documented. These codes optimize billing and documentation for inflammatory muscle and skin diseases with diverse clinical presentations.

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

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)