ICD-10 Code C94.42 – Acute panmyelosis with myelofibrosis, in relapse (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C94.42 – Acute panmyelosis with myelofibrosis, in relapse
What it is
This code identifies a relapse of acute panmyelosis with myelofibrosis, a rare and aggressive bone marrow cancer affecting multiple blood cell lines. Use it when the condition has returned after prior remission or treatment response.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include pancytopenia, marrow fibrosis, and evidence of recurrent acute myeloid-type disease, but you should code only when relapse is clearly documented.
When to use this code
Use C94.42 when the provider documents acute panmyelosis with myelofibrosis as recurrent, relapsed, or returned after prior improvement. It is appropriate for follow-up encounters, active management, or reassessment of a known diagnosis after relapse is confirmed.
Do not infer relapse from persistent symptoms alone. If the record only states a history of the disorder or an unspecified myeloid malignancy, check documentation before assigning this code.
Do not use for
Do not use this code for initial diagnosis, remission status, or unspecified myelofibrosis without relapse. Check documentation if the chart does not clearly state recurrent disease.
Coding tip
Look for explicit terms such as “in relapse,” “recurrent,” or “returned after remission” before coding C94.42.