2022 ICD-10-CM Diagnosis Code C91.6

Prolymphocytic leukemia of T-cell type

    2016 2017 2018 2019 2020 2021 2022 Non-Billable/Non-Specific Code
  • C91.6 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
  • The 2022 edition of ICD-10-CM C91.6 became effective on October 1, 2021.
  • This is the American ICD-10-CM version of C91.6 - other international versions of ICD-10 C91.6 may differ.
The following code(s) above C91.6 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to C91.6:
  • C00-D49
    2022 ICD-10-CM Range C00-D49


    • Functional activity
    • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
    • Morphology [Histology]
    • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
    • Primary malignant neoplasms overlapping site boundaries
    • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
    • Malignant neoplasm of ectopic tissue
    • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
  • C81-C96
    2022 ICD-10-CM Range C81-C96

    Malignant neoplasms of lymphoid, hematopoietic and related tissue

    Type 2 Excludes
    • 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)
    Malignant neoplasms of lymphoid, hematopoietic and related tissue
  • C91
    ICD-10-CM Diagnosis Code C91

    Lymphoid leukemia

      2016 2017 2018 2019 2020 2021 2022 Non-Billable/Non-Specific Code
    Type 1 Excludes
    • personal history of leukemia (Z85.6)
    Lymphoid leukemia
Clinical Information
  • A lymphoid leukemia characterized by a profound lymphocytosis with or without lymphadenopathy, hepatosplenomegaly, frequently rapid progression, and short survival. It was formerly called t-cell chronic lymphocytic leukemia.
  • An aggressive t-cell leukemia, characterized by the proliferation of small to medium sized prolymphocytes with a mature t-cell phenotype, involving the blood, bone marrow, lymph nodes, liver, spleen, and skin. (who, 2001)
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

Diagnosis Index entries containing back-references to C91.6:

ICD-10-CM Codes Adjacent To C91.6
C91.31 …… in remission
C91.32 …… in relapse
C91.4 Hairy cell leukemia
C91.40 …… not having achieved remission
C91.41 …… in remission
C91.42 …… in relapse
C91.5 Adult T-cell lymphoma/leukemia (HTLV-1-associated)
C91.50 …… not having achieved remission
C91.51 …… in remission
C91.52 …… in relapse
C91.6 Prolymphocytic leukemia of T-cell type
C91.60 …… not having achieved remission
C91.61 …… in remission
C91.62 …… in relapse
C91.A Mature B-cell leukemia Burkitt-type
C91.A0 …… not having achieved remission
C91.A1 …… in remission
C91.A2 …… in relapse
C91.Z Other lymphoid leukemia
C91.Z0 …… not having achieved remission
C91.Z1 …… in remission

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.