Essential Thrombocythemia and Polycythemia Vera: Focus on Clinical Practice

Area of Science:

• Hematology
• Oncology
• Molecular Diagnostics

Background:

• Bone marrow (BM) morphology is key for diagnosing essential thrombocythemia (ET) and polycythemia vera (PV).
• Genetic mutations (JAK2, CALR, MPL) aid diagnosis but JAK2 mutations are found in both PV and ET.
• Distinguishing ET from PV can be challenging, especially in cases of "masked" polycythemia vera.

Purpose of the Study:

• To highlight the diagnostic roles of bone marrow morphology and genetic mutations in ET and PV.
• To clarify the utility of JAK2, CALR, and MPL mutation screening in differentiating these myeloproliferative neoplasms.
• To outline current treatment strategies based on risk stratification for ET and PV patients.

Main Methods:

• Morphological assessment of bone marrow samples.
• Screening for JAK2, CALR, and MPL mutations.
• Clinical evaluation including patient age, thrombosis history, and cardiovascular risk factors.

Main Results:

• JAK2 mutation is expected in PV; its absence makes the diagnosis unlikely.
• Approximately 60% of ET patients have JAK2 mutations, necessitating BM examination for differentiation from PV.
• CALR and MPL mutations are found in JAK2-unmutated ET, but BM morphology is essential for triple-negative ET and distinguishing from other myeloproliferative neoplasms.

Conclusions:

• Bone marrow morphology remains indispensable for diagnosing ET and PV, complementing genetic mutation analysis.
• Genetic screening (CALR, then MPL) is valuable for JAK2-unmutated ET but does not obviate the need for BM examination.
• Treatment decisions for ET and PV are guided by risk stratification, with distinct approaches for low-risk and high-risk patients.