A50.5 vs K00.4
A50.5 and K00.4 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.
The official note, declared on K00.4
Hutchinson's teeth and mulberry molars in congenital syphilis (A50.5)
A50.5
Other late congenital syphilis, symptomatic
Not billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A50-A64
Use when the record says
- Any congenital syphilitic condition specified as late or manifest two years or more after birth.
K00.4
Disturbances in tooth formation
Billable
- Chapter 11
- Diseases of the digestive system
- Section
- K00-K14
Use when the record says
- Aplasia and hypoplasia of cementum
- Dilaceration of tooth
- Enamel hypoplasia (neonatal) (postnatal) (prenatal)
- Regional odontodysplasia
- Turner's tooth
Indexed under
- Dilaceration, tooth
- Odontodysplasia, regional
- Amelogenesis imperfecta › nonhereditaria
- Aplasia › cementum
- Calcification › dentinal papilla
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