ICD-10 Code C91.0 – Acute lymphoblastic leukemia [ALL] (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.0 – Acute lymphoblastic leukemia [ALL]
What it is
C91.0 identifies acute lymphoblastic leukemia, a fast-growing blood cancer that starts in immature lymphoid cells. It is used when documentation specifically states ALL.
Clinical signs
Common findings include fatigue, pallor, easy bruising, recurrent infections, bone pain, and enlarged lymph nodes or spleen. Clinical features vary; refer to documentation.
When to use this code
Use C91.0 when the provider documents acute lymphoblastic leukemia or ALL, including newly diagnosed or established cases. Apply it when the record clearly identifies the lymphoblastic subtype. If the note is vague or only says leukemia, check documentation.
Do not use for
Do not use this code for other leukemia types, such as acute myeloid leukemia or chronic leukemias. Do not assign it when the chart does not clearly specify ALL.
Coding tip
Verify the exact leukemia subtype in the assessment or pathology report before coding.