M30.8 vs M35.1
M30.8 and M35.1 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on M35.1
polyangiitis overlap syndrome (M30.8)
M30.8
Other conditions related to polyarteritis nodosa
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M30-M36
Use when the record says
- Polyangiitis overlap syndrome
Indexed under
- Polyangiitis › overlap syndrome
- Syndrome › polyangiitis overlap
- Polyarteritis › nodosa › related condition NEC
M35.1
Other overlap syndromes
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M30-M36
Use when the record says
- Mixed connective tissue disease
Indexed under
- Disease, diseased › mixed connective tissue
- Syndrome › connective tissue › overlap NEC
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