FY2027
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Excludes1 pair

L50- vs T78.3-

L50 and T78.3 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 L50
angioneurotic edema (T78.3)
L50

Urticaria

Not billable
Chapter 12
Diseases of the skin and subcutaneous tissue
Section
L49-L54
T78.3

Angioneurotic edema

Not billable
Chapter 19
Injury, poisoning and certain other consequences of external causes
Section
T66-T78
Use when the record says
  • Allergic angioedema
  • Giant urticaria
  • Quincke's edema
Indexed under
  • Angioedema (allergic) (any site) (with urticaria)
  • Angioneurotic edema (allergic) (any site) (with urticaria)
  • Bannister's disease
  • Quincke's disease or edema
  • Allergy, allergic › angioneurotic edema

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