Excludes1 pair

I96 vs L88

I96 and L88 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 I96
pyoderma gangrenosum (L88)
I96

Gangrene, not elsewhere classified

BillableUnspecified
Chapter 9
Diseases of the circulatory system
Section
I95-I99
Use when the record says
  • Gangrenous cellulitis
Indexed under
  • Acrosphacelus
  • Gangrene, gangrenous (connective tissue) (dropsical) (dry) (moist) (skin) (ulcer)
  • Gangrene, gangrenous › abdomen (wall)
  • Gangrene, gangrenous › auricle
  • Gangrene, gangrenous › cutaneous, spreading
L88

Pyoderma gangrenosum

Billable
Chapter 12
Diseases of the skin and subcutaneous tissue
Section
L80-L99
Use when the record says
  • Phagedenic pyoderma
Indexed under
  • Phagedena › geometric
  • Pyoderma, pyodermia › gangrenosum
  • Pyoderma, pyodermia › phagedenic

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