FY2027
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Excludes1 pair

L85.9 vs R23.4

L85.9 and R23.4 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.

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