Haematology Flashcards
Immunophenotypic markers typical of CLL:
Co-expression of B-cell and T-cell markers is characteristic:
B-cell: CD19, CD20, CD23
* If CD23 absent, need to rule out mantle cell lymphoma
T-cell: CD5
Kappa light chain restriction on scattergram.
Symptoms of lymphoproliferative disorders:
Often none - detected incidentally on blood test
Lymphadenopathy
Fatigue
Weight loss
Night sweats (common in HL; uncommon in high grade or indolent lymphomas)
Signs of lymphoproliferative disorders:
Often none
Palpable lymphadenopathy Splenomegaly Hepatomegaly (rarely) Signs of anaemia (if present), jaundice (if haemolytic), or bleeding (if thrombocytopaenic) Lymphatic obstruction (almost never)
CLL vs MBL (Monoclonal B-cell Lymphocytosis):
Arbitrary cut off of 5000/uL B-cells of CLL/SLL (small lymphocytic lymphoma) type.
MBL =
5000, but develop symptoms or signs).
Differentials for CLL (to rule out):
- Mantle cell lymphoma - suspect of CD23 absent –> oncogene bcl-1 (cyclin D1) usually positive in MCL, negative in CLL.
- Hairy cell leukaemia - hairy cells (cytoplasmic projections) or immunophenotype differentiates: CD5 and CD21 negative, and positive for CD25, CD11c, and CD103.
- Prolymphocytic leukaemia - usually differentiated on blood film morphology (prolymphocytes occur in CLL but are abundant in PLL); PLL is CD5 negative.
PLL - >55% circulating cells in peripheral blood are prolymphocytes (immature-appearing cells - approx. twice the size of normal lymphocyte, abundant cytoplasm, round
CLL staging system:
Rai (US) vs Binnet (Europe)
Binnet: number of nodal sites and presence of cytopaenias.
Rai and median survival:
- Low risk - Stage 0 - lymphocytosis - 12.5yrs
- Intermediate risk: lymphadenopthy / organomegaly
> Stage I - lymphadenopathy - 5-8yrs
Stage II - splenomegaly or hepatomegaly
- High risk: cytopaenias - Stage III - anaemia (Hb Stage IV - thrombocytopaenia (<100)
Prognostic features in CLL:
Age
Stage
Short lymphocyte Doubling-time (<12 months)
Serum markers: Beta2 microglobulin concentration
Surface marker expression (worse prognosis): ZAP70, CD38
Genetic risk factors (FISH): 17p deletion, 11q deletion, p53 mutation.
[Note: Trisomy 12q or normal karyotype or 13q deletion have better prognosis]
IgVH gene: unmutated = worse prognosis; mutated = better prognosis
Complications of CLL:
> Autoimmune - eg. haemolytic anaemia or ITP - not sign of progression
(need to differentiate ITP from BM involvement or splenic sequestration)
> Hypogammaglobulinaemia, with recurrent infections requiring hospitalisation
> Transformation ( to PLL, or Richter’s - usually to large cell lymphoma)
> Other malignancies (especially GU, GI, cutaneous; but also head & neck, Kaposi, lung, brain).
Treatment of CLL:
Observe at least 6 months, unless: symptomatic, advanced stage, autoimmune complications.
Standard of care:
- Fludarabine
- Cyclophosphamide
- Rituximab
Lomger-term rituximab improves survival.
Usually not STC as older population.
CLL and SLL - defintions:
Chronic lymphocytic leukemia (CLL) is one of the chronic lymphoproliferative disorders (lymphoid neoplasms). It is characterized by a progressive accumulation of functionally incompetent lymphocytes, which are monoclonal in origin.
CLL is considered to be identical (ie, one disease at different stages) to the mature (peripheral) B cell neoplasm small lymphocytic lymphoma (SLL), one of the indolent non-Hodgkin lymphomas.
The term CLL is used when the disease manifests primarily in the bone marrow and blood, whereas the term SLL is used when involvement is primarily nodal.
While there is some difference to the treatment of early stage CLL and SLL, the treatment of advanced stage disease is the same.
Median survival in CLL:
10 years
Essential thrombocythaemia diagnostic criteria:
- Sustained platelet count >450 x 109/L
- Predominantly megakaryocytic hyperplasia in
bone marrow - NOT –
CML (BCR/ABL negative),
PV (Red cell mass measurement if Hct >40%)
Primary Myelofibrosis
Myelodysplastic Syndrome
or other neoplasm - JAK2V617F +ve or no evidence for reactive
thrombocytosis (incl. normal ferritin levels)
Aplastic anaemia - definition:
The bone marrow fails to produce cells, leading to a hypocellular marrow and pancytopaenia.
Causes of aplastic anaemia:
Congenital 15-20% - eg. Fanconi anaemia Idiopathic Drugs Infection Toxins Radiation exposure
Fanconi anaemia is a congenital form of aplastic anaemia which is an AR, X-linked disorder. What are the other associated clinical features?
Microcephaly Short stature Skin defects Hypogonadism Urogenital abnormalities
Investigations for pancytopaenia (when suspecting aplastic anaemia):
- Blood count - note: aplastic anaemia usually shows pancytopaenia, but may have isolated cytopaenia.
- Blood film: ?signs of myelodsyplasia
- Bone marrow biopsy: hypocellular, increased fat content, decreased haematopoietic elements.
- Cytogenetics for chromosomal abnormalities of bone marrow disorders eg. hypocellular MDS
- B12, folate
- LFTs
- Viral serology: HIV, HBV, HCV
- Chromosomal breakpoint analysis if suspect Fanconi anaemia (<50yo)
- Flow cytometry to exclude paroxysmal nocturnal haemoglobinuria (deficiencies of CD55, CD59)
Presentation of paroxysmal nocturnal haemoglobinuria (PNH):
- haemolytic anaemia: fatigue, lethargy, breathlessness, jaundice
- haemoglobinuria (may be paroxysmal in a few patients)
- pancytopaenia - bruising / bleeding, infections, anaemia (common even without a BM syndrome)
- unprovoked atypical thrombosis: eg. mesenteric or cerebral infarction; Budd-chiari (hepatic vein). Cause unclear.
Other symptoms (related to NO deficiency as bound by free Hb): oesophageal spasm, abdominal pain, erectile dysfunction.
Paroxysmal nocturnal haemoglobinuria - findings on flow cytometry:
Deficiency of CD55 and CD59 on surface of peripheral erythrocytes or leucocytes
When to anticoagulate in paroxysmal nocturnal haemoglobinuria:
Acute thrombotic event
OR
Consider if >50% cells are CD55 or CD59 deficient (but no thrombosis)
Median survival in paroxysmal nocturnal haemoglobinuria; usual causes of death:
10-15 years
Thrombosis or progressive pancytpaenia
Pathogenesis of PNH:
Acquired abnormality of PIG-A gene due to somatic mutation
–>
Populations of abnormal RBCs (“PNH cells”) that are deficient in terminal complement inhibitors (GPI-linked proteins on red and white cell surfaces - see below)
–>
PNH RBCs sensitive to persistent terminal complement-mediated destruction
–>
Intravascular haemolysis.
Genetic mutation in PNH leads to a partial or complete absence of GPI-linked proteins on red & white cell surfaces, eg:
- CD59 (membrane inhibitor of reactive lysis)
- CD55 (decay accelerating factor)
Note: The proportion of affected cells and degree of deficiency relates to haemolysis rate / presentation.
Treatment:
- Treat IDA (iron can number of deficient clones –> precipitate haemolysis)
- Transfusion
- Eculizumab: humanised mab which binds c5 and prevents terminal complement activation (hence need for 3-5yrly meningococcal vaccination - but still 0.5%/yr risk)
- Possibly high-dose EPO; G-CSF
- Anticoagulation when indicated (thrombosis / >50% deficient clones)
Level of blasts on BM aspirate required for AML diagnosis?
> 20%
What are auer rods?
structures seen in myeloid cells on microscopy that are indicative of AML
Chromosomal abnormality classic for promyelocytic leukaemia?
Translocation: t15:17
Inheritance pattern of haemophilia A and B
X-linked recessive disorders
Sideroblastic anaemia diagnosis:
- microcytosis
- ring sideroblasts in BM
- evidence of iron overload
Why are ABO antigens important?
Antibodies to ABO antigens are IgM, activate complement, and cause immediate intravascular haemolysis.
Blood of adults contain antibodies to ABO antigens (anti-A, anti-B or anti-A,B). First detectable at 3-6months of age.
Why are Rhesus D (RhD) antigens important?
Antibody to RhD (called anti-D) is produced by RhD negative individuals when exposed to RhD positive red blood cells.
Anti-D causes severe haemolysis (acute and delayed).
Antibodies can cross the placenta.
Commonest cause of severe haemolytic disease of the foetus / newborn.
15% caucasians are RhD negative.
How important is blood group in platelet transfusion?
Platelet transfusion contains plasma.
Therefore, if not exact match:
- ABO compatible but plasma incompatible: +ve DAT / possible haemolysis
- ABO incompatible but plasma compatible: decreased platelet lifespan
- RhD+ platelets to RhD- patients –> Anti-D Abs (doesn’t affect pt, but may have implications for women who become pregnant)
Universal RBC donor?
Group O
Universal plasma (FFP, cryo) donor?
Group AB
Criteria for Transfusion Associates Lung Injury:
TRALI:
- ALI:
- acute onset
- hypoxaemia (sats<300)
- CXR bilateral infiltrates
- no e/o LA hypertension - ≤6 hrs from transfusion
- No ALI prior to transfusion
- no alternative risk factor for ALI
(If there is but others satisfied = POSSIBLE TRALI)
Which blood products are highest risk for contamination and transfusion-associated sepsis?
Platelets - because stored at room temperature.
(1/25,000 –> sepsis events)
RBCs - refridgerated 2-6 degrees (1/250,000 units –> sepsis events)
FFP, Cryo - frozen / refridgerated
Pre-storage leucodepletion of all red cells and platelet products has which benefits?
- ↓ FNHTR (febrile non-haemolytic transfusion reactions)
- ↓alloimmunisation (platelet refractoriness, organ transplant donor matches)
- ↓ risk of CMV
- Possible: ↓ transfusion-associated GVHD (TaGVHD), ↓prions (vCJD), ↓ transfusion related immune modulation (TRIM)
Three pillars of patient blood management:
- PRE-OP: optimise Hb pre-operatively (reversible causes?)
- INTRA-OP: minimise blood loss (identify bleeding risks, surgical technique, cell salvage)
- POST-OP: optimise patient’s tolerance of anaemia (optimise oxygen delivery - cardiorespiratory reserves ; restrictive transfusion policy)
Definition of massive transfusion:
≥10 units RBCs in 24hrs.
Recommended ratio of blood products in massive transfusion:
1 : 1 : 1
RBCs : Plts : Plasma
However, no prospective studies to confirm yet.
Why not use MTP ratios of blood products in all patients with high transfusion requirement (but not MT)?
Increased exposure to plasma (blood components) appear to outweigh benefits
→ ↑ risk of TRALI, TACO, anaphylaxis, MODS, ARDS
Red cell storage lesions (5):
- Loss of 2,3-DPG → ↓oxygen delivery as ↑ affinity of Hb
- Loss of ATP, ADP, AMP → RBC shape change
20-25% not viable - Na+/K+ pump paralaysed at 2-6’ → Na+ enters and K+ leaves RBCs
- Microvesiculation –> loss of membrane –> tendency to haemolysis, change in deformality, osmotic fragility
- Accumulation of free Hb in supernatant
Most common underlying cause of FNHTRs in platelet transfusions?
Donor cytokines released by donor white cells during storage.
Therefore pre-storage leucodepletion particularly effective.
Most common underlying cause of FNHTRs in RBC transfusions?
Donor leucocytes (reaction of recipient Abs to donor leucocytes).
Leucodepletion by pre-storage and by bedside-filter both effective.
Approx 1% (episodes/units transfused) pre-universal leucodepletion. Now closer to 0.1%.
Purpose of irradiation of blood products?
Inactivate WBCs and decrease risk of TaGVHD in immunodeficient patients.
Relative frequency of transfusion reactions (10):
- Allergic reaction 1-3%
- TACO (transfusion-assoc. cardiac overload) ≤1%
- FNHTR (febrile non-haemolytic) 0.1-1%
- TRALI
- DHTR (delayed haemolytic)
- Acute haemolytic
- Anaphylaxis
- Sepsis (platelets)
- HBV
- HIV, HCV
Relative mortality rates of transfusion reactions:
- TRALI
- HTR (haemolytic)
- sepsis
- TACO
- Anaphylaxis
- Ta-GVHD
Classic coagulation pathway is still useful, but what is the current thinking about the three main steps of invivo coagulation?
- Injury at site exposes TF –> activates Factor VII –> Activates Factor X –> Prothrombin to Thrombin
- Amplification phase: Thrombin –> activation of Factor VIII and V + activation of platelets
- Coagulation occurs at platelets surfaces, within fibrin clot formation and cross-linking to form stable clot.
When will thrombin time be prolonged?
Heparin
Dysfibrinogenaemia
Prolonged aPTT normalises with mixing study. Cause?
Mixing study: add normal plasma to patient’s (1 : 1) and test aPTT.
aPTT normalises if Factor deficiency is the cause
Prolonged aPTT normalises with mixing study. Cause?
Mixing study: add normal plasma to patient’s (1 : 1) and test aPTT.
aPTT does not normalise if an inhibitor is present (eg. acquired Factor VIII inhibitor or Lupus Anticoagulant).
Is mucosal bleeding / petechiae more typical for platelet disorder or coagulation factor deficiency?
Platelet disorder
Are haemarthroses and large ecchymoses more typical of platelet disorder or coagulation factor deficiency?
Coagulation factor deficiency.
Eg. haemophilia;
Acquired factor VIII inhibitor; Warfarin
D-dimer looks for ____?
Fibrin degradation products.
High if large clot, DIC (many other causes).
Ecarin time:
?? Liver disease vs Vit K deficiency
Factor XII deficiency and contact factor deficiency are associated with which clinical picture?
Prolonged aPTT (other coag studies normal) but no increased bleeding or thrombosis.