ICD-10 Code C91.10 – Chronic lymphocytic leukemia of B-cell type not having achieved remission (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.10 – Chronic lymphocytic leukemia of B-cell type not having achieved remission
What it is
This code identifies chronic lymphocytic leukemia (CLL) of B-cell type that is still active and has not reached remission. Use it when the record clearly states CLL without remission or persistent disease.
Clinical signs
CLL may be found with lymphocytosis, enlarged lymph nodes, splenomegaly, or fatigue. Clinical features vary; refer to documentation and confirm that the leukemia is documented as not in remission.
When to use this code
Use this code when the provider documents B-cell CLL and specifically notes that remission has not been achieved. It also fits follow-up visits for known active CLL when the disease status remains unchanged. If the chart only says “history of leukemia,” check documentation.
Do not use for
Do not use this code for CLL in remission, because a different code applies. Also avoid it when the diagnosis is uncertain, the leukemia type is not B-cell, or the note refers only to past disease.
Coding tip
Code the remission status exactly as documented; when it is unclear, query the provider before assigning C91.10.