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ICD-10-CM 2027 diagnosis code

C91.Z2Other lymphoid leukemia, in relapse

✓ Billable / specificCC — complication/comorbidity

C91.Z2 is a valid, billable ICD-10-CM code for other lymphoid leukemia, in relapse. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About C91.Z2

C91.Z2 is the ICD-10-CM diagnosis code for other lymphoid leukemia, in relapse. It belongs to category C91 (lymphoid leukemia), block C81-C96 (malignant neoplasms of lymphoid, hematopoietic and related tissue) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C91.Z (other lymphoid leukemia), C91.Z2 is specifically for other lymphoid leukemia, in relapse. Related codes cover not having achieved remission (C91.Z0) and in remission (C91.Z1).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 820 (Lymphoma and Leukemia with Major O.R. Procedures with MCC, relative weight 6.2481), DRG 821 (Lymphoma and Leukemia with Major O.R. Procedures with CC, relative weight 2.2023), DRG 822 (Lymphoma and Leukemia with Major O.R. Procedures without CC/MCC, relative weight 1.1272), DRG 823 (Lymphoma and Non-Acute Leukemia with Other Procedures with MCC, relative weight 4.6059), DRG 824 (Lymphoma and Non-Acute Leukemia with Other Procedures with CC, relative weight 2.2515), DRG 825 (Lymphoma and Non-Acute Leukemia with Other Procedures without CC/MCC, relative weight 1.2995) and 3 more, in MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 204.82 (other lymphoid leukemia, in relapse).

Notes that apply from higher levels

Instructions written at a parent level also apply to C91.Z2.

› From C91 Lymphoid leukemia
Excludes1
  • personal history of leukemia (Z85.6)

Broader instructions also apply from C81-C96 Malignant neoplasms of lymphoid, hematopoietic and related tissue and Chapter 2: Neoplasms.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 204.82Other lymphoid leukemia, in relapseapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about C91.Z2

Is C91.Z2 billable?

Yes. C91.Z2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C91.Z2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C91.Z2 as a principal diagnosis.

Is C91.Z2 a CC or MCC?

C91.Z2 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does C91.Z2 group to?

C91.Z2 is used in the MS-DRG v44.0 logic for MS-DRG 820 (Lymphoma and Leukemia with Major O.R. Procedures with MCC), MS-DRG 821 (Lymphoma and Leukemia with Major O.R. Procedures with CC), MS-DRG 822 (Lymphoma and Leukemia with Major O.R. Procedures without CC/MCC), MS-DRG 823 (Lymphoma and Non-Acute Leukemia with Other Procedures with MCC), MS-DRG 824 (Lymphoma and Non-Acute Leukemia with Other Procedures with CC), MS-DRG 825 (Lymphoma and Non-Acute Leukemia with Other Procedures without CC/MCC) and 3 more. Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for C91.Z2?

The CMS General Equivalence Mappings map C91.Z2 to ICD-9-CM 204.82.