C90 vs C90.0
C90 and C90.0 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 C90.0
solitary myeloma (C90.3-)
C90.0
Multiple myeloma
Not billable
- Chapter 2
- Neoplasms
- Section
- C81-C96
Use when the record says
- Kahler's disease
- Medullary plasmacytoma
- Myelomatosis
- Plasma cell myeloma
Indexed under
- Kahler's disease
- Myeloma (multiple)
- Myelomatosis
- Myeloma › plasma cell (multiple)
- Plasmacytoma › medullary
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