M26 vs Q67.4
M26 and Q67.4 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.
Dentofacial anomalies [including malocclusion]
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M26-M27
Other congenital deformities of skull, face and jaw
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q65-Q79
- Congenital depressions in skull
- Congenital hemifacial atrophy or hypertrophy
- Deviation of nasal septum, congenital
- Squashed or bent nose, congenital
- Atrophy, atrophic › hemifacial (of)
- Depression › skull (acute) (mental)
- Flattening › nose
- Friedreich's › facial hemihypertrophy
- Hypertrophy, hypertrophic › hemifacial
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
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