Wk3 - Haematology Flashcards
(186 cards)
Site of haemopoiesis in foetus, infants and adults
Foetus:
0-2 months - yolk sac
2-7 months - liver, spleen
5-9 months - bone marrow
Infants: Bone marrow (all bones - not just axial skeleton)
Adults: Bone marrow (vertebrae, ribs, sternum, skull, sacrum, pelvis, ends of femurs)
Pluripotent stem cell divides to
Myeloid stem cell and lymphoid stem cell
Haemopoietc stem cell characteristics
Self renewal capacity
Unspecialised
Ability to differentiate (mature)
Quiescent (i.e. not undergoing cell cycle, in in G0) - only undergoes occasional cell division
Where are haemopoietic stem cells found?
Bone marrow
Peripheral blood after treatment with G-CSF (stem cells can be obtained out of bone marrow by G-CSF)
Umbilical cord blood
Haemopoietic stem cells can underrgo one of 3 things,,,
Self-renewal (identical copy)
Apoptosis
Differentiation
Haemopoietic stem cells can undergo one of 3 types of differentiation
1) Symmetrical division, contraction of stem cell numbers
2) Asymmetrical division, maintenance of stem cell numbers
3) Symmetrical division, expansion of stem cell numbers
Stroma = ?
The bone marrow microenvironment that supports the developing haemopoietic cell
Rich environment for growth and development of stem cells.
Stromal cells supported by an extracellular matrix.
BOne marrow microenvironemnt contains a number of different cells…
e.g. macrophages, fibroblasts, endothelial cells, fat cells, reticulum cells
These produce e.g. collagen, fibronectin, laminin, proteoglycans
What site is bone marrow aspirate taken from?
Iliac crest
Hereditary conditions impairing bone marrow function?
Thalassaemia, sickle cell anaemia, Fanconi anaemia, Schwachman-Diamond syndrome Hereditary leukaemia (very rare)
Acquired conditions impairing bone marrow function
Aplastic anaemia, leukaemia, myelodysplasia, myeloproliferative disorders, lymphoproliferative disorders, metastatic malignancy e.g. breast, infections e.g. TB/HIV, drugs and toxins, chemotherapy, haematinic deficiency
Principles of leukaemogenesis
HSC–> LSC –> Clonogenic leukemia cells –> non-clonogenic leukaemia blast cells
A multistep process
Neoplastic cell is a haemopoietic stem cell or early myeloid or lymphoid cell.
Dysregulation of cell growth and differentiation (associated with mutations)
Proliferation of the leukaemic clone with differentiation blocked at an early stage.
Haematological malignancies and pre-malignant conditions are termed ___ if they arise from a single ancestral cell
‘clonal’
Chronic myelogenous leukemia
Increase in WBCs (from myeloid lineage)
CML is acuased by BCr gene on chromosome 22 translocating to Abl gene on chromosome 9 –> this creates a new type of chromosome - Philadelphia chromosome.
This leads to increased pleuripotent stem cell production from bone marrow –> increased WBC
Chronic myelogenous leukemia
Increase in WBCs (from myeloid lineage)
CML is caused by BCr gene on chromosome 22 translocating to Abl gene on chromosome 9 –> this creates a new type of chromosome - Philadelphia chromosome.
This leads to increased pleuripotent stem cell production from bone marrow –> increased WBC
Myeloproliferative disprders =
clonal disorders of haemopoiesis leading to increased numbers of one or more mature blood progency
Classical MPDs (myeloproliferative disorders) are…
Polycythaemia rubrae vera (inc. RBCs)
Essential thrombocytosis (inc. platelets)
Myelofibrosis (inc. fibrous tissue)
Myeloproliferative disorders are variably associated with what mutation
JAK2V617F (point mutation) and calreticulin mutation
Myeloproliferative disorders have potential t transform into
AML
Clinical features of essential thrombocytosis
50% cases carry JAK2v617F, 50% carry calreticulin mutation.
Continuum with PRV Thrombotic complications Haemorrhagic complications Splenomegaly Transformation to PRV or myelofibrosis Leukaemic transmation in 3%
Treatment of essential thrombocytosis
Low risk (<40y with no high risk features e.g. diabetes) - aspirin or anti-platelet agent
Intermediate risk (40-60y with no high risk features) - aspirin +/- hydroxycarbamide)
High risk (>60y with thrombotic risk factors): 1st line = hydroxycarbamide + aspirin 2nd line = anagrelide + aspirin IFN alpha -usefu with pregnancy Busulphan (e.g. someone not independent) JAK2 inhibitors e.g. ruxolitinib
Describe JAK2 inhibitors
JAK2 mutations result in continuous activation of JAK receptor regardless of ligand binding
Ruxolitinib - inhibits JAK1 and 2, reduces splenomegaly, main side effect is thrombocytopenia, results in jak2 pos and neg patients
Describe myelodysplastic syndromes (MDS)
Characterised by dysplasia and ineffective haemopoiesis
May be secondary to previous chemotherapy or radiotherapy.
May have increased myeloblasts.
Often associated with acquired cytogenic abnormalities e.g. monosomy 5, monosomy 7, trisomy 8.
Majority characterised by progressive bone marrow failure
Some progress to AML
MDS clinical features
Predominantly affects the elderly
Majority present with fatigue due to anaemia
Fewer present with infections or bleeding or FBC