A 55-year-old man with a history of essential thrombocythemia for 8 years presents with progressive splenomegaly, leukoerythroblastic blood picture with teardrop cells, and bone marrow showing marked reticulin fibrosis with atypical megakaryocytic hyperplasia. JAK2 V617F mutation is positive. Which diagnosis best describes this transformation?

• A Secondary myelofibrosis following polycythemia vera
• B Primary myelofibrosis (PMF)
• C Myelodysplastic syndrome with fibrosis
• D Post-essential thrombocythemia myelofibrosis (post-ET MF) ✓

Explanation

This represents post-essential thrombocythemia myelofibrosis (post-ET MF), a well-recognized complication of ET occurring in approximately 3-10% of cases over 10 years. The WHO criteria require documented prior ET, grade 2-3 reticulin fibrosis, and features of myelofibrosis (splenomegaly, leukoerythroblastosis, teardrop cells). This is distinct from primary myelofibrosis (no preceding MPN) and post-PV MF (preceded by polycythemia vera). JAK2 V617F is positive in approximately 50-60% of ET and PMF cases.

Reference: WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 5th (2022) ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.