Dermato(poly)myositis in neoplastic disease

This code signifies dermatomyositis or polymyositis that is directly associated with an underlying neoplastic (cancerous) disease. It describes an autoimmune inflammatory myopathy where the body's immune system attacks muscle tissue, often accompanied by characteristic skin rashes, and is triggered by or occurs concurrently with a malignancy.

Use this code when documentation clearly links the patient's dermatomyositis or polymyositis to an active or recently diagnosed malignancy. This typically applies when the myositis is considered a paraneoplastic syndrome. Supporting documentation would include physician notes explicitly stating the association, pathology reports confirming malignancy, and diagnostic findings consistent with dermatomyositis/polymyositis.

• Always sequence the underlying malignancy code first, as it is the etiology of the dermato(poly)myositis.
• Ensure the medical record explicitly states the causal link between the neoplasm and the myositis; mere co-occurrence is not sufficient.
• Do not confuse with primary dermatomyositis (M33.0-) or polymyositis (M33.1-) without a documented neoplastic association.