Acute leukemia of unspecified cell type, in relapse

This code signifies a recurrence of acute leukemia where the specific cellular origin (e.g., myeloid, lymphoid) has not been determined or documented. The patient is experiencing a relapse of their previously diagnosed acute leukemia.

Apply this code when documentation clearly states "acute leukemia, unspecified cell type, in relapse" or similar phrasing indicating a return of the disease without further cellular differentiation. This is appropriate when the specific subtype of acute leukemia is not yet known or has not been specified by the clinician.

• Do not use this code if the specific cell type (e.g., acute lymphoblastic, acute myeloid) is documented; instead, use the more specific relapse code.
• Always sequence this code as the primary diagnosis when the patient is admitted for treatment of the relapse.
• Ensure documentation explicitly states "in relapse" to differentiate from initial diagnosis or remission.