M85- vs Q78.0
M85 and Q78.0 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.
Other disorders of bone density and structure
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M80-M85
Osteogenesis imperfecta
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q65-Q79
- Fragilitas ossium
- Osteopsathyrosis
- Adair-Dighton syndrome (brittle bones and blue sclera, deafness)
- Eddowes syndrome (-Spurway)
- Ekman's syndrome (brittle bones and blue sclera)
- Lobstein disease or syndrome (-Ekman)
- Osteogenesis imperfecta
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