Myelofibrosis

Introduction

Neoplasia of mature myeloid cells most notably megakaryocytes Most commonly seen in older adults (5th/6th decade) Result of a JAK2 kinase mutation  Megakaryocyte hyperplasia results in fibrotic obliteration of the bone marrow result of increased production of PDGF

Presentation

Symptoms splenomegaly  secondary to extramedullary hematopoiesis bleeding megakaryocytes are dysfunctional thrombosis platelets can rupture which stimulates coagulation cascade

Evaluation

Peripheral blood smear tear-drop RBC   membrane is disrupted when RBC passed through fibrosis to leave bone marrow nucleated RBCs band granulocytes