L85.9 vs R23.4
L85.9 and R23.4 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 R23.4
epidermal thickening NOS (L85.9)
L85.9
Epidermal thickening, unspecified
BillableUnspecified
- Chapter 12
- Diseases of the skin and subcutaneous tissue
- Section
- L80-L99
Indexed under
- Hyperkeratosis
- Pachyderma, pachydermia
- Hyperplasia, hyperplastic › epithelial
- Thickening › epidermal
- Hyperplasia, hyperplastic › epithelial › skin
R23.4
Changes in skin texture
Billable
- Chapter 18
- Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
- Section
- R20-R23
Use when the record says
- Desquamation of skin
- Induration of skin
- Scaling of skin
Indexed under
- Crusts
- Desquamation, skin
- Inelasticity, skin
- Parakeratosis
- Scabs
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