2027 ICD-10-CM Diagnosis Code C91Lymphoid leukemia

ICD-10-CM Codes›C00–D49›C81-C96›C91

ICD-10-CM C91
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

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
Short Description
Lymphoid leukemia
Same as the full description in the CMS dataset.
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

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to C91: its own notes plus those printed at block C81-C96 and Chapter 2. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

  • personal history of leukemia (Z85.6)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block C81-C96 Malignant neoplasms of lymphoid, hematopoietic and related tissue applies to 533 codes
  • Kaposi's sarcoma of lymph nodes (C46.3)
  • secondary and unspecified neoplasm of lymph nodes (C77.-)
  • secondary neoplasm of bone marrow (C79.52)
  • secondary neoplasm of spleen (C78.89)

Notes

General instructions on how these codes are used.

From Chapter 2 (C00-D49) Neoplasms applies to 1,730 codes
  • Functional activity
  • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
  • Morphology [Histology]
  • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
  • Primary malignant neoplasms overlapping site boundaries
  • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
  • Malignant neoplasm of ectopic tissue
  • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name C91, its category, or a range that includes it.

Applicable To 2

These notes mention C91.

  • Z80.6 Family history of leukemia
    Conditions classifiable to C91-C95
  • Z85.6 Personal history of leukemia
    Conditions classifiable to C91-C95

Excludes1 3

These codes carry an Excludes1 note naming C91: they are not reported together with it, unless the two conditions are unrelated.

  • D72.8 Other specified disorders of white blood cells
    leukemia (C91-C95)
  • D72.825 Bandemia
    leukemia (C91.-, C92.-, C93.-, C94.-, C95.-)
  • T66 Radiation sickness, unspecified
    leukemia (C91-C95)

Code First 3

These codes say to code first a condition named in the note, and C91 is one of the conditions named.

  • M36.1 Arthropathy in neoplastic disease
    leukemia (C91-C95)
  • N16 Renal tubulo-interstitial disorders in diseases classified elsewhere
    leukemia (C91-C95)
  • R50.81 Fever presenting with conditions classified elsewhere
    leukemia (C91-C95)

Clinical InformationClinical

  • Leukemia, Lymphoid

    leukemia associated with hyperplasia of the lymphoid tissues and increased numbers of circulating malignant lymphocytes and lymphoblasts.

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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About C91Overview

What is the ICD-10 code for lymphoid leukemia?

C91 is the ICD-10-CM category for lymphoid leukemia, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

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.

Can C91 be reported with Z85.6?

Not as a rule. The Excludes1 note on C91 lists "personal history of leukemia (Z85.6)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).