Acute lymphoblastic leukemia, in relapse

This code signifies a recurrence of acute lymphoblastic leukemia (ALL) after a period of remission. It indicates that the disease, characterized by an overproduction of immature lymphocytes, has returned and is actively progressing.

Apply this code when documentation clearly states a diagnosis of ALL that has relapsed. This typically occurs after a patient has undergone treatment and achieved remission, only for the leukemia to reappear. Supporting documentation would include physician notes detailing the relapse, bone marrow biopsy results confirming the presence of blasts, and treatment plans for recurrent ALL.

• Ensure documentation explicitly states "in relapse" for ALL; do not assume relapse based on treatment alone.
• Distinguish carefully from ALL in remission (C91.01) or ALL not specified as in remission or relapse (C91.00).
• Always sequence this code as the primary diagnosis when the patient is admitted or seen for treatment of the relapsed ALL.