2026 ICD-10-CM Diagnosis Code C91Lymphoid leukemia

ICD-10-CM Codes›C00–D49›C81-C96›C91

ICD-10-CM C91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C91 is a non-billable ICD-10-CM category code for lymphoid leukemia, so it cannot be submitted on claims. Use a more specific code from this category instead, such as C91.00, C91.01, C91.02, and C91.10.

Code Identity

ICD-10-CM Code
C91
Billable Status
No — Non-Billable Category
Code Describes
Lymphoid leukemia
Chapter
C81-C96
Malignant neoplasms of lymphoid, hematopoietic and related tissue

Code Classification

ChapterC00–D49Neoplasms
SectionC81-C96Malignant neoplasms of lymphoid, hematopoietic and related tissue
CategoryC91Lymphoid leukemia
This CodeC91Lymphoid leukemia

Specific Coding for Lymphoid leukemiaOverview

Non-specific codes like C91 require more characters. Use one of these billable codes instead:

  • C91.0 for Acute lymphoblastic leukemia [ALL]

  • Use C91.00 for Acute lymphoblastic leukemia not having achieved remission

  • Use C91.01 for Acute lymphoblastic leukemia, in remission

  • Use C91.02 for Acute lymphoblastic leukemia, in relapse

  • C91.1 for Chronic lymphocytic leukemia of B-cell type

  • Use C91.10 for Chronic lymphocytic leukemia of B-cell type not having achieved remission

  • Use C91.11 for Chronic lymphocytic leukemia of B-cell type in remission

  • Use C91.12 for Chronic lymphocytic leukemia of B-cell type in relapse

  • C91.3 for Prolymphocytic leukemia of B-cell type

  • Use C91.30 for Prolymphocytic leukemia of B-cell type not having achieved remission

  • Use C91.31 for Prolymphocytic leukemia of B-cell type, in remission

  • Use C91.32 for Prolymphocytic leukemia of B-cell type, in relapse

  • C91.4 for Hairy cell leukemia

  • Use C91.40 for Hairy cell leukemia not having achieved remission

  • Use C91.41 for Hairy cell leukemia, in remission

  • Use C91.42 for Hairy cell leukemia, in relapse

  • C91.5 for Adult T-cell lymphoma/leukemia (HTLV-1-associated)

  • Use C91.50 for Adult T-cell lymphoma/leukemia (HTLV-1-associated) not having achieved remission

  • Use C91.51 for Adult T-cell lymphoma/leukemia (HTLV-1-associated), in remission

  • Use C91.52 for Adult T-cell lymphoma/leukemia (HTLV-1-associated), in relapse

  • C91.6 for Prolymphocytic leukemia of T-cell type

  • Use C91.60 for Prolymphocytic leukemia of T-cell type not having achieved remission

  • Use C91.61 for Prolymphocytic leukemia of T-cell type, in remission

  • Use C91.62 for Prolymphocytic leukemia of T-cell type, in relapse

  • C91.9 for Lymphoid leukemia, unspecified

  • Use C91.90 for Lymphoid leukemia, unspecified not having achieved remission

  • Use C91.91 for Lymphoid leukemia, unspecified, in remission

  • Use C91.92 for Lymphoid leukemia, unspecified, in relapse

  • C91.A for Mature B-cell leukemia Burkitt-type

  • Use C91.A0 for Mature B-cell leukemia Burkitt-type not having achieved remission

  • Use C91.A1 for Mature B-cell leukemia Burkitt-type, in remission

  • Use C91.A2 for Mature B-cell leukemia Burkitt-type, in relapse

  • C91.Z for Other lymphoid leukemia

  • Use C91.Z0 for Other lymphoid leukemia not having achieved remission

  • Use C91.Z1 for Other lymphoid leukemia, in remission

  • Use C91.Z2 for Other lymphoid leukemia, in relapse

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Type 1 Excludes

  • personal history of leukemia Z85.6

Patient EducationClinical

Acute Lymphocytic Leukemia

Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job:

The full article covers:

  • What is leukemia?
  • What is acute lymphocytic leukemia (ALL)?
  • What causes acute lymphocytic leukemia (ALL)?
  • Who is at risk for acute lymphocytic leukemia (ALL)?
  • What are the symptoms of acute lymphocytic leukemia (ALL)?
  • How is acute lymphocytic leukemia (ALL) diagnosed?
  • What are the treatments for acute lymphocytic leukemia (ALL)?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C91Overview

Is C91 (Lymphoid leukemia) a billable code?

No. This is a category header that groups the codes for lymphoid leukemia, and headers cannot be submitted on claims. Claims for lymphoid leukemia need a more specific code from this category, such as C91.00, C91.01, and C91.02.