FY2027
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Excludes1 pair

A18.4 vs L93-

A18.4 and L93 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 L93
lupus exedens (A18.4)
A18.4

Tuberculosis of skin and subcutaneous tissue

Billable
Chapter 1
Certain infectious and parasitic diseases
Section
A15-A19
Use when the record says
  • Erythema induratum, tuberculous
  • Lupus exedens
  • Lupus vulgaris NOS
  • Lupus vulgaris of eyelid
  • Scrofuloderma
  • Tuberculosis of external ear
Indexed under
  • Acnitis (primary)
  • Bazin's disease (primary) (tuberculous)
  • Lichenoides tuberculosis (primary)
  • Scrofulide (primary) (tuberculous)
  • Scrofuloderma, scrofulodermia (any site) (primary)
L93

Lupus erythematosus

Not billable
Chapter 12
Diseases of the skin and subcutaneous tissue
Section
L80-L99

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