ICD-10 Code C94.32 – Mast cell leukemia, in relapse (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C94.32 – Mast cell leukemia, in relapse
What it is
C94.32 identifies mast cell leukemia that has returned after a period of remission. Use it when the record clearly states relapse or recurrent disease.
Clinical signs
Clinical features vary; refer to documentation. Mast cell leukemia is a rare, aggressive mast cell neoplasm, and relapse may be described by recurrent marrow or systemic disease.
When to use this code
Use C94.32 when the provider documents mast cell leukemia as relapsed, recurrent, or returned after prior response. This code fits follow-up encounters where the active condition is the relapse itself. If the record only says history of mast cell leukemia without relapse, check documentation before coding.
Do not use for
Do not use this code for mast cell leukemia without relapse, remission status, or unspecified disease course. Do not assign it when documentation supports only a history of the condition.
Coding tip
Look for explicit relapse language in the assessment or problem list before assigning C94.32.