Excludes1 pair
C90- vs C90.0-
C90 and C90.0 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 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
- 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