L85.0 vs Q80
L85.0 and Q80 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 distinction is congenital vs acquired.
The official note, declared on L85.0
congenital ichthyosis (Q80.-)
L85.0
Acquired ichthyosis
Billable
- Chapter 12
- Diseases of the skin and subcutaneous tissue
- Section
- L80-L99
Indexed under
- Ichthyosis › acquired (congenital)
- Xeroderma › acquired
- Disease, diseased › alligator-skin › acquired
- Disease, diseased › fish-skin › acquired
Q80
Congenital ichthyosis
Not billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q80-Q89
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