C91 – Lymphoid leukemia

ICD-10-CM 2027 diagnosis code · Malignant neoplasms of lymphoid, hematopoietic and related tissue

Non-billable header

ICD-10-CM code C91

Code: C91 (claims format: C91)
Description: Lymphoid leukemia
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 2. Neoplasms (C00-D49)
Block: C81-C96 Malignant neoplasms of lymphoid, hematopoietic and related tissue

Billable codes under C91

C91 is a header code and cannot be used on claims. Choose the most specific code:

C91.0 – Acute lymphoblastic leukemia [ALL]Header (more codes below)
C91.1 – Chronic lymphocytic leukemia of B-cell typeHeader (more codes below)
C91.3 – Prolymphocytic leukemia of B-cell typeHeader (more codes below)
C91.4 – Hairy cell leukemiaHeader (more codes below)
C91.5 – Adult T-cell lymphoma/leukemia (HTLV-1-associated)Header (more codes below)
C91.6 – Prolymphocytic leukemia of T-cell typeHeader (more codes below)
C91.A – Mature B-cell leukemia Burkitt-typeHeader (more codes below)
C91.Z – Other lymphoid leukemiaHeader (more codes below)
C91.9 – Lymphoid leukemia, unspecifiedHeader (more codes below)

Notes for C91

Excludes1 (not coded here):

personal history of leukemia (Z85.6)

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Block C81-C96

Excludes2 (not included here):

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)

Frequently asked questions

What is ICD-10 code C91?

C91 is the ICD-10-CM code for lymphoid leukemia, in the block C81-C96 (Malignant neoplasms of lymphoid, hematopoietic and related tissue).

Is C91 a billable code?

No. C91 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.