Excludes1 pair
C00- vs C43.0
C00 and C43.0 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
malignant melanoma of lip (C43.0)
C43.0
Malignant melanoma of lip
Billable
- Chapter 2
- Neoplasms
- Section
- C43-C44
Indexed under
- Melanoma › skin › lip (lower) (upper)
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