2025 ICD-10-CM Diagnosis Code C91

Lymphoid leukemia

C91 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
The 2025 edition of ICD-10-CM C91 became effective on October 1, 2024.
This is the American ICD-10-CM version of C91 – other international versions of ICD-10 C91 may differ.

Type 1 Excludes

The following code(s) above C91 contain annotation back-references

that may be applicable to C91:

Clinical Information

A malignant lymphocytic neoplasm of b-cell or t-cell lineage involving primarily the bone marrow and the peripheral blood. This category includes precursor or acute lymphoblastic leukemias and chronic leukemias.
A progressive, proliferative disease of blood cells, originating from lymphoid cells.
A type of cancer in which the bone marrow makes too many lymphocytes (white blood cells).
Leukemia associated with hyperplasia and overactivity of the lymphoid tissue; there are increased numbers of circulating malignant lymphocytes and lymphoblasts.
Leukemia associated with hyperplasia of the lymphoid tissues and increased numbers of circulating malignant lymphocytes and lymphoblasts.

Code History

2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
2017 (effective 10/1/2016): No change
2018 (effective 10/1/2017): No change
2019 (effective 10/1/2018): No change
2020 (effective 10/1/2019): No change
2021 (effective 10/1/2020): No change
2022 (effective 10/1/2021): No change
2023 (effective 10/1/2022): No change
2024 (effective 10/1/2023): No change
2025 (effective 10/1/2024): No change

Code annotations containing back-references to C91: