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ICD-10-CM 2027 diagnosis code

C91.ZOther lymphoid leukemia

Not billable — use a more specific code

C91.Z is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it.

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.Z

C91.Z is the ICD-10-CM diagnosis code for other lymphoid leukemia. It belongs to category C91 (lymphoid leukemia), block C81-C96 (malignant neoplasms of lymphoid, hematopoietic and related tissue) and chapter 2 (neoplasms). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

Within C91, choose C91.Z (Other lymphoid leukemia) only when documentation doesn't support a more specific option: acute lymphoblastic leukemia [ALL] (C91.0), chronic lymphocytic leukemia of B-cell type (C91.1), Prolymphocytic leukemia of B-cell type (C91.3), Hairy cell leukemia (C91.4), adult T-cell lymphoma/leukemia (HTLV-1-associated) (C91.5), Prolymphocytic leukemia of T-cell type (C91.6), unspecified (C91.9) and mature B-cell leukemia Burkitt-type (C91.A).

To report this condition, pick the subcode that matches the documentation: C91.Z0 (not having achieved remission), C91.Z1 (in remission) and C91.Z2 (in relapse).

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

Specific codes under C91.Z

Coding notes

Applicable toConditions and synonyms classified to this code
  • T-cell large granular lymphocytic leukemia (associated with rheumatoid arthritis)

Notes that apply from higher levels

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

› 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.

Alphabetic index entries

2 entries

Terms in the official ICD-10-CM index that lead to C91.Z.

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.Z

Is C91.Z billable?

No. C91.Z is a header code. Report one of its more specific subcodes instead.