C94.30

HCC Category Mapping

What This Code Means

A rare blood cancer where mast cells multiply uncontrollably in the bone marrow and blood, and have not responded to treatment.

Coding Tips

• •Mast cell leukemia is distinct from systemic mastocytosis; verify correct diagnosis in documentation
• •Use this code only when remission has not been achieved after initial therapy

Clinical Significance

Mast cell leukemia not having achieved remission is an extremely rare and aggressive form of systemic mastocytosis where mast cells constitute at least 20% of bone marrow cells and circulate in the peripheral blood. It carries the worst prognosis among mast cell neoplasms with median survival measured in months.

Documentation Requirements

• ✓Documentation must include bone marrow biopsy demonstrating at least 20% mast cells, peripheral blood smear findings showing circulating mast cells, serum tryptase levels (typically markedly elevated), and KIT D816V mutation status.
• ✓Treatment response confirming no remission achievement must be recorded.

Commonly Confused Codes