Myeloid Disoders

Auer rods indicate what cell lineage

Needle‑shaped azurophilic inclusions specific for myeloid lineage. Myeloblasts

Pathophysiology of CML

BCR‑ABL fusion due to t(9;22) chromosome translocation → constitutive tyrosine kinase activity → uncontrolled myeloid proliferation with preserved maturation.

Clinical presentation of CML

Fatigue, weight loss, splenomegaly, leukocytosis with left shift, basophilia

Morphologic features of CML

Myelocyte bulge, hypercellular marrow, increased small hypolobated megakaryocytes.

Expected cytogenetic/molecular abnormality in CML

t(9;22) Philiadelphia translocation

How to calculate Absolute Neutrophil Count (ANC)?

ANC=(Segs + bands) x WBC

Pathophysiology of Polycythemia Vera (PV)

JAK2 mutation → uncontrolled erythroid proliferation. High RBCs, high Hb

Pathophysiology of Essential Thrombocytemia (ET)

JAK2/CALR/MPL mutations → megakaryocytic proliferation. High thrombocytosis >450k

Pathophysiology of Primary Myelofibrosis (PMF)

Megakaryocyte proliferation → cytokine release → marrow fibrosis. Splenomegaly + Leukoerythroblastosis. JAK2, CALR, or MPL mutation.

Pathophysiology of Myelodysplastic Syndrome (MDS)

Ineffective and disordered hematopoiesis → cytopenias.

Clinical presentation of MDS

Fatigue, infections, bleeding (organomegaly absent bc no cells to proliferate in blood stream to build up)

Natural history of MDS

Progressive cytopenias → high‑grade MDS → AML transformation.

Hematologic features of MDS

Macrocytic anemia, reticulocytopenia, dysplastic neutrophils, thrombocytopenia, blasts <20%

Morphologic features of MDS

Hypercellular marrow, dyserythropoiesis, dysgranulopoiesis, dysmegakaryocytopoiesis, ringed sideroblasts, blasts <20%

Pathophysiology of AML

Blocked differentiation(no maturation in hematopoesis) → ≥20% blasts.

Clinical presentation of AML

Fatigue, infections, bleeding, organ infiltration (gums, skin), DIC in APL.

Hematologic features of AML

Blasts in peripheral blood, anemia, thrombocytopenia, neutropenia, AUER RODS

Cytogenetic abnormalities defining AML»APL

t(15;17)

Summary of Myeloid Neoplasms