C91.02

HCC Category Mapping

What This Code Means

A fast-growing blood cancer affecting young white blood cells that has returned after a period of remission.

Coding Tips

• •Relapse indicates recurrence of disease after remission; distinguish from initial diagnosis or treatment failure
• •Document the timing of relapse and any new treatment initiated

Clinical Significance

Acute lymphoblastic leukemia in relapse indicates recurrence of blast cells in the bone marrow, blood, or extramedullary sites after achieving remission. Relapsed ALL carries a significantly worse prognosis than initial disease, with lower rates of second remission and overall survival. Treatment typically requires intensive salvage chemotherapy and consideration for stem cell transplantation as the primary curative approach.

Documentation Requirements

• ✓Documentation must demonstrate recurrence of blast cells exceeding 5% in bone marrow or reappearance in peripheral blood after documented remission.
• ✓The timing of relapse (early versus late), site of relapse (bone marrow, central nervous system, testicular, or combined), salvage treatment plan, and candidacy for stem cell transplantation must be documented.

Commonly Confused Codes