Hairy cell leukemia, in relapse

This code signifies a recurrence or worsening of hairy cell leukemia (HCL) after a period of remission or successful treatment. HCL is a rare, slow-growing cancer of the B-lymphocytes, characterized by abnormal "hairy" cells in the blood, bone marrow, and spleen. "In relapse" indicates the disease has returned or progressed.

Apply this code when documentation explicitly states a diagnosis of hairy cell leukemia that is currently in relapse. This typically occurs after initial treatment, where the patient's disease activity has increased, or new symptoms have emerged, requiring further intervention. Supporting documentation includes physician notes, pathology reports confirming HCL, and treatment plans addressing the relapse.

• Ensure documentation clearly specifies "in relapse" for hairy cell leukemia; otherwise, an unspecified or initial encounter code may be more appropriate.
• Do not confuse with codes for initial diagnosis or HCL in remission; the "in relapse" status is critical for accurate coding.
• Sequence this code as the primary diagnosis when the relapse is the reason for the encounter, followed by any associated complications or manifestations.