Excludes1 pair

D01.3 vs D04.5

D01.3 and D04.5 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 D01.3
carcinoma in situ of anal margin (D04.5)
D01.3

Carcinoma in situ of anus and anal canal

Billable
Chapter 2
Neoplasms
Section
D00-D09
Use when the record says
  • Anal intraepithelial neoplasia III [AIN III]
  • Severe dysplasia of anus
Indexed under
  • Dysplasia › anus › severe
  • Neoplasia › intraepithelial › anal › severe
D04.5

Carcinoma in situ of skin of trunk

Billable
Chapter 2
Neoplasms
Section
D00-D09
Use when the record says
  • Carcinoma in situ of anal margin
  • Carcinoma in situ of anal skin
  • Carcinoma in situ of perianal skin
  • Carcinoma in situ of skin of breast

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