Excludes1 pair
M12- vs M79.0
M12 and M79.0 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on M79.0
palindromic rheumatism (M12.3-)
M12
Other and unspecified arthropathy
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M05-M14
M79.0
Rheumatism, unspecified
BillableUnspecified
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M70-M79
Indexed under
- Rheumatism (articular) (neuralgic) (nonarticular)
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027