Hairy cell leukemia not having achieved remission

This code signifies hairy cell leukemia (HCL), a rare, slow-growing B-cell lymphoma, that is currently active and has not yet reached a state of remission. It indicates the presence of the disease without any documented evidence of successful treatment leading to a complete or partial absence of disease activity.

Apply this code when documentation confirms a diagnosis of hairy cell leukemia and explicitly states that the patient is not in remission. This includes initial diagnoses, active disease during treatment, or relapse where remission has not been re-established. Supporting documentation would include pathology reports, hematology consultations, and physician notes detailing active disease.

• Do not use this code if the patient is documented as being in remission; instead, use a code from the C91.41 series.
• Ensure the documentation clearly distinguishes between active disease and remission status to avoid miscoding.
• Sequence this code as a primary diagnosis when it is the reason for the encounter or treatment.