C91.4Header code — not billable
Hairy cell leukemia
- Chapter
- 2. Neoplasms
- Category
- C91
- Effective date
- October 1, 2026
Related codes in category C91
C91Lymphoid leukemiaC91.0Acute lymphoblastic leukemia [ALL]C91.00Acute lymphoblastic leukemia not having achieved remissionYesC91.01Acute lymphoblastic leukemia, in remissionYesC91.02Acute lymphoblastic leukemia, in relapseYesC91.1Chronic lymphocytic leukemia of B-cell typeC91.10Chronic lymphocytic leuk of B-cell type not achieve remisYesC91.11Chronic lymphocytic leukemia of B-cell type in remissionYesC91.12Chronic lymphocytic leukemia of B-cell type in relapseYesC91.3Prolymphocytic leukemia of B-cell typeC91.30Prolymphocytic leukemia of B-cell type not achieve remissionYesC91.31Prolymphocytic leukemia of B-cell type, in remissionYes
Frequently asked questions
What is ICD-10 code C91.4?
C91.4 is an ICD-10-CM diagnosis code for Hairy cell leukemia.
Is C91.4 a billable code?
No. C91.4 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is C91.4 in?
C91.4 falls under Chapter 2: Neoplasms.
When did C91.4 become effective?
C91.4 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to C91.4?
C91.4 belongs to category C91, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.