C91.5 Adult T-cell lymphoma/leukemia (HTLV-1-associated)

The ICD-10-CM code for Adult T-cell lymphoma/leukemia (HTLV-1-associated) is C91.5 (FY2026). It is a non-billable category code — select a more specific code below for claims.

Classification

Chapter

2: Neoplasms (C00-D49)

Section

C81-C96: Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)

Category C91

37 codes (27 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to C91.5:

• Lymphoma (of) (malignant) › adult T-cell (HTLV-1-associated) (acute variant) (chronic variant) (lymphomatoid variant) (smouldering variant)
• Leukemia, leukemic › adult T-cell (HTLV-1-associated) (acute variant) (chronic variant) (lymphomatoid variant) (smouldering variant)

Inclusion Terms

• Acute variant of adult T-cell lymphoma/leukemia (HTLV-1-associated)
• Chronic variant of adult T-cell lymphoma/leukemia (HTLV-1-associated)
• Lymphomatoid variant of adult T-cell lymphoma/leukemia (HTLV-1-associated)
• Smouldering variant of adult T-cell lymphoma/leukemia (HTLV-1-associated)

Official Coding Guidelines

Tx of primary site (TOC entry)

a. Admission/Encounter for treatment of primary site ............................................................. 33

Tx of secondary site (TOC entry)

b. Admission/Encounter for treatment of secondary site .......................................................... 33

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool