Excludes1 pair
C00- vs C4A.0
C00 and C4A.0 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 C00
Merkel cell carcinoma of lip (C4A.0)
C4A.0
Merkel cell carcinoma of lip
Billable
- Chapter 2
- Neoplasms
- Section
- C43-C44
Indexed under
- Carcinoma › Merkel cell › lip
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