M66.0 vs M71.2
M66.0 and M71.2 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 M71.2
synovial cyst of popliteal space with rupture (M66.0)
M66.0
Rupture of popliteal cyst
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M65-M67
Indexed under
- Cyst › Baker's › ruptured (colloid) (mucous) (simple) (retention)
M71.2
Synovial cyst of popliteal space [Baker]
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M70-M79
Indexed under
- Cyst › Baker's (colloid) (mucous) (simple) (retention)
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