ICD-10 Code C91.50 – Adult T-cell lymphoma/leukemia (HTLV-1-associated) not having achieved remission (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.50 – Adult T-cell lymphoma/leukemia (HTLV-1-associated) not having achieved remission
What it is
C91.50 identifies adult T-cell lymphoma/leukemia linked to HTLV-1 infection when the disease is still active and remission has not been documented. Use it for the specified malignant lymphoid disorder, not for a resolved or in-remission case.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings may include lymphadenopathy, skin lesions, hepatosplenomegaly, or leukemia-like blood involvement, but you should code only what is clearly documented.
When to use this code
Use this code when the provider documents adult T-cell lymphoma/leukemia associated with HTLV-1 and states that remission has not been achieved. It also fits active disease during initial diagnosis, persistent disease, or relapse if the record does not indicate remission. Check documentation for the exact disease status.
Do not use for
Do not use this code for adult T-cell lymphoma/leukemia in remission or for unspecified leukemia/lymphoma without HTLV-1 association. If the chart does not confirm the specific diagnosis or remission status, check documentation.
Coding tip
Match the code to both the HTLV-1 association and the nonremission status; either element missing means you should verify the record.