Excludes1 pair
C93- vs D46.Z
C93 and D46.Z 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 D46.Z
chronic myelomonocytic leukemia (C93.1-)
C93
Monocytic leukemia
Not billable
- Chapter 2
- Neoplasms
- Section
- C81-C96
Use when the record says
- monocytoid leukemia
D46.Z
Other myelodysplastic syndromes
Billable
- Chapter 2
- Neoplasms
- Section
- D37-D48
Indexed under
- Myelodysplasia › specified NEC
- Myelodysplastic syndrome › specified NEC
- Syndrome › myelodysplastic › specified NEC
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