M85.8 vs Q77.4
M85.8 (Other specified disorders of bone density and structure) compared with Q77.4 (Achondroplasia), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. M85.8 carries an Excludes1 note covering Q77.4: “osteosclerosis congenita (Q77.4)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| M85.8Other specified disorders of bone density and structure | Q77.4Achondroplasia | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) | Q00-Q99 — Congenital Malformations, Deformations and Chromosomal Abnormalities (Q00-Q99) |
| Definition | Other specified disorders of bone density and structure is a non-billable ICD-10-CM category code (M85.8). | Achondroplasia is a billable ICD-10-CM diagnosis code (Q77.4). |
| Includes | Hyperostosis of bones, except skull Osteosclerosis, acquired | Hypochondroplasia Osteosclerosis congenita |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources