Chronic leukemia of unspecified cell type, in relapse

This code signifies a chronic form of leukemia where the specific cell lineage (e.g., myeloid, lymphoid) has not been documented, and the disease is currently in an active phase of recurrence or progression after a period of remission. It indicates a persistent, long-term malignancy of the blood-forming cells that is no longer controlled by prior treatment.

Apply this code when documentation clearly states "chronic leukemia, unspecified cell type, in relapse" or similar phrasing indicating a return of the disease. This is appropriate for patients undergoing treatment for a relapse of their chronic leukemia when the specific type of chronic leukemia is not specified.

• Ensure documentation explicitly states "in relapse" to differentiate from "in remission."
• Avoid using this code if the specific cell type (e.g., chronic myeloid leukemia, chronic lymphocytic leukemia) is known and documented; use the more specific code.
• Sequence this code as the primary diagnosis when the relapse is the reason for the encounter.