Early/prefibrotic primary myelofibrosis in patients who were initially diagnosed with essential thrombocythemia

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• The 2016 World Health Organization (WHO) criteria introduced early/prefibrotic primary myelofibrosis (PMF) as a subtype of myeloproliferative neoplasms (MPN).
• Diagnosis relies on bone marrow (BM) biopsy histopathology and clinical factors like leukocytosis, anemia, elevated lactate dehydrogenase (LDH), and splenomegaly.

Purpose of the Study:

• To determine the prevalence of early/prefibrotic PMF in patients initially diagnosed with essential thrombocythemia (ET).
• To compare clinical characteristics and outcomes between early/prefibrotic PMF and ET patients.

Main Methods:

• Re-evaluation of BM biopsy samples from 42 patients previously diagnosed with ET using the 2016 WHO criteria.
• Comparison of clinical parameters (LDH, splenomegaly) and survival outcomes (myelofibrosis-free, acute myeloid leukemia-free) between the identified early/prefibrotic PMF and ET groups.

Main Results:

• Early/prefibrotic PMF was diagnosed in 14% of patients previously classified as ET.
• Patients with early/prefibrotic PMF exhibited higher LDH values and increased frequencies of splenomegaly compared to ET patients.
• Myelofibrosis-free survival and acute myeloid leukemia-free survival were comparable between early/prefibrotic PMF and ET groups.

Conclusions:

• A significant proportion of ET diagnoses may represent early/prefibrotic PMF, necessitating accurate diagnostic evaluation.
• Understanding the distinct clinical features of early/prefibrotic PMF is crucial for appropriate patient management.
• Further research is needed to clarify the clinical characteristics of Japanese ET patients and differentiate them from early/prefibrotic PMF.