ICD-10 Code C91.00 – Acute lymphoblastic leukemia not having achieved remission (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.00 – Acute lymphoblastic leukemia not having achieved remission
What it is
This code identifies acute lymphoblastic leukemia, a fast-growing blood cancer, when the disease has not yet gone into remission. Use it when the record clearly states the leukemia is active or persistent.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include fatigue, infections, bruising, bleeding, anemia, and abnormal blood counts, but you should code only what is documented.
When to use this code
Use C91.00 when the provider documents acute lymphoblastic leukemia and states it has not achieved remission, is refractory, or remains active after treatment. It also fits ongoing management of known ALL without remission status. If remission status is not documented, check the record before assigning this code.
Do not use for
Do not use this code for ALL in remission or for history of leukemia only. If the documentation is unclear about remission status, check documentation rather than assuming C91.00.
Coding tip
Always look for explicit wording about remission status in the assessment, because that determines whether C91.00 is appropriate.