2026 ICD-10-CM Diagnosis Code C91.02Acute lymphoblastic leukemia, in relapse

ICD-10-CM Codes›C00–D49›C81-C96›C91

ICD-10-CM C91.02
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C91.02 is a billable ICD-10-CM diagnosis code for acute lymphoblastic leukemia, in relapse. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 820 through 822, 834 through 839. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Leukemia - acute lymphoblastic leukemia (ALL).

Code Identity

ICD-10-CM Code
C91.02
Billable Status
Yes — Valid for Submission
Code Describes
Acute lymphoblastic leukemia, in relapse
Short Description
Acute lymphoblastic leukemia, in relapse
Same as the full description in the CMS dataset.
Parent Code
C91.0
Acute lymphoblastic leukemia [ALL]

Code Classification

ChapterC00–D49Neoplasms
SectionC81-C96Malignant neoplasms of lymphoid, hematopoietic and related tissue
CategoryC91Lymphoid leukemia
This CodeC91.02Acute lymphoblastic leukemia, in relapse

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO059
Leukemia - acute lymphoblastic leukemia (ALL)
Default principal diagnosis: inpatient Yes · outpatient Yes

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.

Convert C91.02 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
204.02 Act lymp leuk in relapse
Exact Match The mapping is direct, with no qualifiers.

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 C91.02Overview

Is C91.02 (Acute lymphoblastic leukemia [ALL]) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report acute lymphoblastic leukemia, in relapse on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C91.02 group to?

When acute lymphoblastic leukemia, in relapse is the principal diagnosis on an inpatient stay, it groups to MS-DRG 820, 821, 822, 834, 835, 836, 837, 838, 839, with relative weights from 1.2040 to 5.8648 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C91.02?

Under the General Equivalence Mappings, acute lymphoblastic leukemia, in relapse converts to ICD-9-CM 204.02 (act lymp leuk in relapse). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.