C91.4 vs C94
C91.4 (Hairy cell leukemia) compared with C94 (Other leukemias of specified cell type), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. C94 carries an Excludes1 note covering C91.4: “leukemic reticuloendotheliosis (C91.4-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| C91.4Hairy cell leukemia | C94Other leukemias of specified cell type | |
|---|---|---|
| Billing status | Non-billable header | Non-billable header |
| Classification | C00-D49 — Neoplasms (C00-D49) | C00-D49 — Neoplasms (C00-D49) |
| Definition | Hairy cell leukemia is a non-billable ICD-10-CM category code (C91.4). | Other leukemias of specified cell type is a non-billable ICD-10-CM category code (C94). |
| Includes | Leukemic reticuloendotheliosis | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources