Lymphoid leukemia (C91) ICD-10-CM
The C91 code range covers lymphoid leukemia with 37 ICD-10-CM diagnosis codes. 27 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- personal history of leukemia Z85.6
Codes in the C91 Range 37 codes · 27 billable
- C91 Lymphoid leukemiaNon-billable
- C91.0 Acute lymphoblastic leukemia [ALL]Non-billable
- C91.00 Acute lymphoblastic leukemia not having achieved remission
- C91.01 Acute lymphoblastic leukemia, in remission
- C91.02 Acute lymphoblastic leukemia, in relapse
- C91.1 Chronic lymphocytic leukemia of B-cell typeNon-billable
- C91.10 Chronic lymphocytic leukemia of B-cell type not having achieved remission
- C91.11 Chronic lymphocytic leukemia of B-cell type in remission
- C91.12 Chronic lymphocytic leukemia of B-cell type in relapse
- C91.3 Prolymphocytic leukemia of B-cell typeNon-billable
- C91.30 Prolymphocytic leukemia of B-cell type not having achieved remission
- C91.31 Prolymphocytic leukemia of B-cell type, in remission
- C91.32 Prolymphocytic leukemia of B-cell type, in relapse
- C91.4 Hairy cell leukemiaNon-billable
- C91.40 Hairy cell leukemia not having achieved remission
- C91.41 Hairy cell leukemia, in remission
- C91.42 Hairy cell leukemia, in relapse
- C91.5 Adult T-cell lymphoma/leukemia (HTLV-1-associated)Non-billable
- C91.50 Adult T-cell lymphoma/leukemia (HTLV-1-associated) not having achieved remission
- C91.51 Adult T-cell lymphoma/leukemia (HTLV-1-associated), in remission
- C91.52 Adult T-cell lymphoma/leukemia (HTLV-1-associated), in relapse
- C91.6 Prolymphocytic leukemia of T-cell typeNon-billable
- C91.60 Prolymphocytic leukemia of T-cell type not having achieved remission
- C91.61 Prolymphocytic leukemia of T-cell type, in remission
- C91.62 Prolymphocytic leukemia of T-cell type, in relapse
- C91.9 Lymphoid leukemia, unspecifiedNon-billable
- C91.90 Lymphoid leukemia, unspecified not having achieved remission
- C91.91 Lymphoid leukemia, unspecified, in remission
- C91.92 Lymphoid leukemia, unspecified, in relapse
- C91.A Mature B-cell leukemia Burkitt-typeNon-billable
- C91.A0 Mature B-cell leukemia Burkitt-type not having achieved remission
- C91.A1 Mature B-cell leukemia Burkitt-type, in remission
- C91.A2 Mature B-cell leukemia Burkitt-type, in relapse
- C91.Z Other lymphoid leukemiaNon-billable
- C91.Z0 Other lymphoid leukemia not having achieved remission
- C91.Z1 Other lymphoid leukemia, in remission
- C91.Z2 Other lymphoid leukemia, in relapse
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the C91 range.
Adult T-Cell Leukemia/Lymphoma
A peripheral (mature) T-cell neoplasm linked to the human T-cell leukemia virus type 1 (HTLV-1). Adult T-cell leukemia/lymphoma is endemic in several regions of the world, in particular Japan, the Caribbean, and parts of Central Africa.
Adult T-Cell Leukemia/Lymphoma in Remission
A finding of adult T-cell leukemia/lymphoma that is not growing and responds to treatment.
B-Cell Prolymphocytic Leukemia in Remission
A finding of B-cell prolymphocytic leukemia that is not growing and responds to treatment.
Burkitt Leukemia in Remission
A finding of Burkitt leukemia that is not growing and responds to treatment.
Chronic Lymphocytic Leukemia in Remission
A finding of chronic lymphocytic leukemia that is not growing and responds to treatment.
Leukemia, Hairy Cell
A neoplastic disease of the lymphoreticular cells which is considered to be a rare type of chronic leukemia; it is characterized by an insidious onset, splenomegaly, anemia, granulocytopenia, thrombocytopenia, little or no lymphadenopathy, and the presence of hairy or flagellated cells in the blood and bone marrow.
Leukemia, Lymphoid
Leukemia associated with HYPERPLASIA of the lymphoid tissues and increased numbers of circulating malignant LYMPHOCYTES and lymphoblasts.
Precursor Cell Lymphoblastic Leukemia-Lymphoma
A neoplasm characterized by abnormalities of the lymphoid cell precursors leading to excessive lymphoblasts in the marrow and other organs. It is the most common cancer in children and accounts for the vast majority of all childhood leukemias.
Recurrent Adult T-Cell Leukemia/Lymphoma
The reemergence of adult T-cell leukemia/lymphoma after a period of remission
Recurrent B-Cell Prolymphocytic Leukemia
The reemergence of a B-cell prolymphocytic leukemia after a period of remission.
Recurrent Burkitt Leukemia
The reemergence of Burkitt leukemia after a period of remission.
Recurrent Chronic Lymphocytic Leukemia
The reemergence of chronic lymphocytic leukemia after a period of remission.
Recurrent T-Cell Prolymphocytic Leukemia
The reemergence of T-cell prolymphocytic leukemia after a period of remission.
T-Cell Prolymphocytic Leukemia in Remission
A finding of T-cell prolymphocytic leukemia that is not growing and responds to treatment.
About the C91 Code Range
Lymphoid leukemia involves overgrowth of lymphoid tissue and increased numbers of cancerous lymphoid cells circulating in the blood.
The subdivisions distinguish acute lymphoblastic leukemia (C91.0), chronic lymphocytic leukemia of B-cell type (C91.1), and prolymphocytic leukemia of B-cell or T-cell type (C91.3 and C91.6). They also distinguish hairy cell leukemia (C91.4), adult T-cell lymphoma/leukemia (C91.5), and mature B-cell leukemia Burkitt-type (C91.A). Separate subdivisions identify unspecified (C91.9) and other lymphoid leukemia (C91.Z).
Each subdivision separates leukemia that has not achieved remission, is in remission, or is in relapse.
Questions About This Page
How many billable codes are in the C91 range?
Of the 37 codes in this range, 27 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the C91 range classify?
The range classifies lymphoid leukemia. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
