AIM Concept Integration
3rd Year MBBS
Blood & Immunology
3rd Year MBBS
Blood & Immunology
Topic 3 — Myeloid Neoplasms, Myelodysplastic Syndromes and Myeloproliferative Disorders
Connect the major mechanisms, morphology, diagnostic clues and treatment links for rapid revision.
1. THE TOPIC IN ONE CONNECTED FLOW
These disorders begin with abnormal hematopoietic cells, but their behavior differs. The key is to identify whether the abnormal clone mainly causes blast accumulation, excess mature-cell production or ineffective dysplastic hematopoiesis, then connect that pattern with the blood film, bone marrow and molecular test.
Normal reference:
Hematopoietic stem cell → myeloid lineage → neutrophils, eosinophils, basophils and monocytes; lymphoid B cells → plasma cells specialized for antibody secretion.
Clonal hematopoietic abnormality
→
Altered proliferation, maturation or survival
→
Characteristic marrow and blood pattern
AML branch
Differentiation block → myeloblast accumulation → suppression of normal marrow → anemia, infection and bleeding → blasts ± Auer rods → marrow, lineage and molecular confirmation.
CML branch
t(9;22) → BCR::ABL1 tyrosine kinase → excessive granulocytic proliferation with preserved maturation → leukocytosis and splenomegaly → BCR::ABL1 confirmation → targeted inhibition.
MDS branch
Clonal stem-cell injury → dysplastic maturation → ineffective hematopoiesis → peripheral cytopenias despite cellular marrow → dysplasia and blast assessment → possible progression toward AML.
Polycythemia vera branch
JAK2-pathway activation → autonomous panmyelosis → erythrocytosis → increased viscosity and thrombosis risk → low erythropoietin with clonal evidence supports diagnosis.
CML treatment link
BCR::ABL1 tyrosine kinase → imatinib or another appropriate BCR::ABL1 inhibitor → reduced leukemic signaling → reduced disease burden.
Leukopenia treatment link
Filgrastim/G-CSF → neutrophil precursor proliferation and maturation → neutrophil recovery; GM-CSF → broader granulocyte-monocyte progenitor stimulation.
2. KEY CLINICAL CONNECTIONS
Acute versus chronic myeloid pattern
AML → maturation failure → many blasts and marrow failure
↓
CML → preserved maturation in chronic phase → granulocytes at several stages with marked leukocytosis
The MDS marrow paradox
Hypercellular dysplastic marrow
→ ineffective maturation and intramedullary cell loss
→ anemia, neutropenia and/or thrombocytopenia in peripheral blood
→ ineffective maturation and intramedullary cell loss
→ anemia, neutropenia and/or thrombocytopenia in peripheral blood
Molecular result → diagnosis and treatment
BCR::ABL1 detected → confirms CML driver → provides a tyrosine-kinase treatment target
JAK2-pathway abnormality + erythrocytosis + low EPO → supports polycythemia vera
Growth factor selection
Predominant neutropenia → G-CSF/filgrastim → neutrophil recovery
Need broader myeloid stimulation → GM-CSF → granulocyte and monocyte progenitor recovery
3. AIM HIGH-YIELD INTEGRATION REVIEW
⭐ AML: impaired myeloid maturation → blast accumulation → normal marrow suppression → fatigue, infection and bleeding; Auer rods support myeloid differentiation.
FAB classification reflects differentiation: M3 is promyelocytic, M4 myelomonocytic, M5 monocytic, M6 erythroid and M7 megakaryoblastic.
⭐ CML: t(9;22) → BCR::ABL1 → constitutive tyrosine-kinase signaling → granulocytic expansion; molecular demonstration confirms the driver and guides targeted therapy.
CML blood and marrow remain linked: marked leukocytosis with different granulocytic maturation stages reflects marked granulocytic marrow hyperplasia rather than an isolated blast disorder.
⭐ MDS: dysplastic marrow may be cellular or hypercellular, yet ineffective hematopoiesis produces peripheral cytopenias; increasing blasts indicate progression toward more aggressive disease.
MDS morphology can involve several lineages: abnormal red-cell maturation, hyposegmented neutrophils, abnormal platelets and ring sideroblasts provide evidence of dysplastic hematopoiesis.
⭐ Polycythemia vera: JAK2-driven panmyelosis → increased red-cell mass and viscosity → headache, microvascular symptoms and thrombosis; low erythropoietin supports autonomous marrow production.
Pharmacology link: filgrastim acts through G-CSF receptors to accelerate neutrophil recovery, whereas GM-CSF stimulates granulocyte and monocyte lineages more broadly.