ICD-10 Code C91.Z – Other lymphoid leukemia (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C91.Z – Other lymphoid leukemia
What it is
This code identifies a lymphoid leukemia that does not fit a more specific ICD-10-CM subtype. Use it for documented lymphoid leukemia when the record names an “other” form or gives insufficient detail for a more specific code.
Clinical signs
Clinical features vary; refer to documentation. Commonly, lymphoid leukemia is recognized by abnormal lymphoid cells in blood, bone marrow, or tissue, with findings that support a leukemia diagnosis rather than a reactive process.
When to use this code
Use C91.Z when the provider documents other lymphoid leukemia and does not identify a more specific subtype. It may also apply when the chart confirms lymphoid leukemia but the available record does not support a narrower category. Check documentation before coding from pathology or oncology notes.
Do not use for
Do not use this code if the record specifies a different leukemia type, such as acute or chronic myeloid disease, or a more exact lymphoid leukemia subtype. Do not assign it when the diagnosis is uncertain. Check documentation.
Coding tip
Code the most specific leukemia type documented, and query the provider if the note only says “lymphoid leukemia” without enough detail.