Other myositis, multiple sites

This code signifies inflammation of muscle tissue (myositis) affecting multiple, distinct anatomical locations throughout the body. It is used when the specific type of myositis is not otherwise classified or when the documentation indicates a generalized myositis without a more precise diagnosis.

Apply this code for patients presenting with widespread muscle inflammation not attributable to a specific, separately classifiable myositis (e.g., polymyositis, dermatomyositis, inclusion body myositis). Documentation should clearly indicate myositis affecting multiple sites and the absence of a more definitive myositis diagnosis.

• Ensure documentation specifies "multiple sites" to differentiate from localized myositis.
• Do not use if a more specific myositis diagnosis (e.g., M33.20 for Polymyositis, unspecified) is documented.
• Consider sequencing with codes for underlying causes or associated conditions, if applicable.