C79.2 vs C7B.1
C79.2 and C7B.1 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on C79.2
secondary Merkel cell carcinoma (C7B.1)
C7B.1
Secondary Merkel cell carcinoma
Billable
- Chapter 2
- Neoplasms
- Section
- C7B
Use when the record says
- Merkel cell carcinoma nodal presentation
- Merkel cell carcinoma visceral metastatic presentation
Indexed under
- Carcinoma › Merkel cell › nodal presentation (malignant)
- Carcinoma › Merkel cell › secondary (malignant)
- Carcinoma › Merkel cell › visceral metastatic (malignant)
- Carcinoma › secondary › Merkel cell (malignant)
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