Haematology Flashcards

1
Q

How can splenomegaly present?

A

Mass in LUQ

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2
Q

What is a good initial test in splenomegaly?

A

Blood film - can indicate changes of e.g. leukaemia or haemolysis

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3
Q

What is a useful test in the diagnosis of leukaemia?

A

Bone marrow biopsy

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4
Q

What can cause splenomegaly?

A

Leukaemia

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5
Q

What is sickle cell disease?

A

A disease of RBCs caused by an autosomal-recessive single gene defect in the beta chain of Hb, which results in sickle cell Hb (HbS)

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6
Q

What is the genetic defect in sickle cell anaemia?

A

Autosomal recessive single gene defect in the beta chain of Hb

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7
Q

In which ethnic groups is sickle cell most common?

A

Those of African, Hispanic and Mediterranean descent

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8
Q

What is the pathophysiology of sickle cell anaemia?

A

1) Sickled RBCs can clump together and obstruct blood flow and break down prematurely
2) They are associated with varying degrees of anaemia
3) Obstruction of small blood capillaries can cause painful crises, damage to major organs, and increased vulnerability to severe infections

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9
Q

What are haematological complications of sickle cell?

A

1) Vaso-occlusive crises
2) Anaemia
3) Iron overload - due to repeated transfusions
4) Aplastic crisis - typically from parvovirus B19 infection
5) Splenic sequestration

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10
Q

What is a hepatological complication of sickle cell?

A

Jaundice

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11
Q

What are some MSK complications of sickle cell?

A

1) Avascular necrosis of the hip or shoulder
2) Dactylitis in infants and children (due to microvascular occlusions)
3) Growth and developmental delay

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12
Q

What is a neurological complication of sickle cell?

A

Stroke

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13
Q

What is a urological complication of sickle cell and how should it be managed?

A

Priapism (common in males aged 12-20 years) - emergency and urology should be urgently contacted, incredibly painful

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14
Q

What is a respiratory complication of sickle cell?

A

Pulmonary hypertension

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15
Q

Which is an ophthalmological complication of sickle cell?

A

Proliferative retinopathy + retinal haemorrhages

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16
Q

What is a vascular complication of sickle cell?

A

Leg ulcers

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17
Q

What can happen to sickle cell patients as a result of repeated transfusions?

A

Iron overload

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18
Q

What causes aplastic crisis in sickle cell patients?

A

Parvovirus B19 infections

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19
Q

What is a vaso-occlusive (sickle) crisis?

A

1) Common, painful complication of sickle cell disease
2) Sickle RBCs clump together and occlude vessels (microvascular occlusion), resulting in ischaemia of downstream tissues

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20
Q

How do vaso-occlusive crises present?

A

1) Pain (hands and feet, abdomen) ± dactylitis - recurrent episodes may cause irreversible damage
2) Acute chest syndrome (resp symptoms e.g. acute dyspnoea, chest pain, hypoxia) - severe form of vaso-occlusive crisis as a result of infarction in the lung parenchyma
3) Can be triggered e.g. by exercise

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21
Q

How do you manage a vaso-occlusive crisis?

A

1) IV opioid pain relief
2) Oxygen as required + IV fluids
3) Treat any suspected infections
4) Top-up transfusions may be required
5) Seek haematology input
6) Incentive spirometry + physiotherapy should additionally be used in cases of acute chest syndrome to minimise the risk of atelectasis

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22
Q

What is long term management of sickle cell disease?

A

1) Top-up transfusions, folic acid and iron chelation - mainstay of regular supportive treatment
2) Immunisations - influenza and pneumococcal
3) Prophylactic penicillin (if asplenic)
4) Genetic counselling

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23
Q

Which immunisations should patients with sickle cell disease receive?

A

Influenza + pneumococcal

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24
Q

What would blood results show in a vaso-occlusive crisis?

A

1) Slightly raised inflammatory markers
2) Mild anaemia - chronic but stable
3) Normal reticulocytes

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25
What is splenic sequestration?
Pooling of blood in the spleen (intrasplenic trapping of RBCs)
26
How does splenic sequestration present?
1) Sudden drop in Hb 2) Haemodynamic instability - shock 3) Splenomegaly (spleen must be double normal size to be palpable) 4) Abdominal pain (due to splenomegaly) 5) Tachycardia 6) Pallor
27
How does aplastic crisis (aka transient red cell aplasia or reticulocytopaenia) present?
1) Tachypnoea + tachycardia in the absence of splenomegaly (in a patient with sickle cell) 2) Tiredness and lethargy + signs of anaemia 3) Sudden drop in Hb 4) Low reticulocyte count < 1% - due to an acute reduction in bone marrow function
28
How would infection triggered haemolytic anaemia present?
Jaundice (rapid onset haemolysis) + splenomegaly
29
What infection can cause haemolytic anaemia?
E coli O157
30
What do blood tests show in haemolytic anaemia?
1) Low Hb 2) Raised unconjugated bilirubin 3) Reticulocytosis (high reticulocyte count) 4) Raised LDH 5) Raised urinary urobilinogen
31
What is the pathophysiology of intravascular haemolytic anaemia?
Intravascular haemolysis occurs in the blood stream, resulting in release of cellular contents esp. Hb into the circulation - this excess of Hb is dealt with in many ways: 1) Combines with haptoglobin, combines with albumin (methaemalbuminaemia) 2) Loss in the urine (haemoglobinuria) 3) Stored in tubular epithelial cells as haemosiderin and shed into the urine (hemosiderinuria)
32
What are the causes of intravascular haemolytic anaemia?
1) Intrinsic cellular injury (e.g. glucose-6-phosphate deficiency - G6PD) 2) Intravascular complement mediated lysis (some autoimmune haemolytic anaemias) 3) Paroxysmal nocturnal haemoglobinuria and acute transfusion reactions 4) Mechanical injury (Microangiopathic haemolytic anaemia and cardiac valves) 5) Autoimmune haemolytic anaemia
33
What is the genetic inheritance of G6PD deficiency?
X-linked recessive
34
What is G6PD deficiency?
A red-cell enzyme disorder (X linked recessive)
35
How does G6PD present?
1) Neonatal period - jaundice 2) Later in life - episodic intravascular haemolysis following exposure to oxidative stressors
36
What are the triggers of G6PD?
1) Intercurrent illness or infection 2) Fava beans 3) Henna 4) Drugs - primaquine, sulfa-drugs, nitrofurantoin, dapsone, NSAIDs/aspirin
37
Which medications can trigger G6PD?
1) Nitrofurantoin 2) NSAIDs/aspirin 3) Primaquine 4) Sulfa-drugs 5) Dapsone
38
Which antibiotic do you avoid in patients with G6PD?
Nitrofurantoin
39
What two investigations do you do for G6PD?
1) Blood film 2) G6PD enzyme assay
40
What is the diagnostic test for G6PD?
G6PD enzyme assay
41
What do you see on blood film in G6PD?
Heinz bodies + bite cells
42
How do you manage G6PD?
1) Avoid precipitants/triggers 2) Rarely require transfusions
43
What is the pathophysiology of extravascular haemolytic anaemia?
Extravascular haemolysis occurs in the reticuloendothelial system (the spleen and liver) and is therefore not associated with dramatic release of free Hb into the circulation
44
What is the reticuloendothelial system?
Spleen + liver
45
How does extravascular haemolytic anaemia present?
Splenomegaly + hepatomegaly
46
What are the causes of extravascular haemolytic anaemia?
1) Abnormal RBCs - sickle cell and hereditary spherocytosis 2) Normal cells marked by antibodies for splenic phaogcytosis
47
What are the causes of extravascular haemolytic anaemia?
1) Abnormal RBCs - sickle cell and hereditary spherocytosis 2) Normal cells marked by antibodies for splenic phagocytosis
48
What is the genetic inheritance of hereditary spherocytosis?
Autosomal dominant
49
In which population is hereditary spherocytosis seen?
Northern Europe
50
What is hereditary spherocytosis?
Autosomal dominant condition caused by mutations in structural red cell membrane proteins
51
Where is the mutation in hereditary spherocytosis?
Structural RBC membrane proteins
52
What is the pathophysiology of hereditary spherocytosis?
1) Abnormal sections of membrane (with mutations in structural RBC membrane proteins) are removed by the spleen, resulting in a reduced SA:volume ratio and causing spherical distortion of cells 2) Eventually, as more membrane is removed, the cells haemolyse (extravascular haemolysis) and are removed from circulation in the spleen.
53
What does hereditary spherocytosis look like on blood film?
Spherocytes (RBCs)
54
How does hereditary spherocytosis present?
Neonatal or childhood onset jaundice/anaemia + splenomegaly
55
What is the key difference between hereditary spherocytosis and G6PD?
Splenomegaly only in hereditary spherocytosis
56
What investigation do you do for hereditary spherocytosis?
Blood film
57
How do you manage hereditary spherocytosis?
1) If mild - conservative management with folic acid supplementation 2) If severe - splenectomy before the age of 5 years is essentially curative
58
What test is used to diagnose autoimmune haemolytic anaemia?
Direct Coombs test
59
How is autoimmune haemolytic anaemia diagnosed?
Direct Coombs test - positive 1) Patients with AIHA have antibodies directed against cell surface markers on the RBC 2) The Coombs test uses antibodies against these autoantibodies to cross link and agglutinate the RBCs
60
What are the two types of Coombs-positive autoimmune haemolytic anaemia?
1) Warm 2) Cold
61
What is the pathophysiology of warm autoimmune haemolytic anaemia?
IgG mediated extravascular haemolytic disease in which the spleen tags cells for splenic phagocytosis
62
What are the causes of warm autoimmune haemolytic anaemia?
1) Idiopathic 2) Lymphoproliferative neoplasms - CLL and lymphoma 3) Drugs incl. methyldopa 4) SLE
63
What is the pathophysiology of cold autoimmune haemolytic anaemia?
IgM-mediated haemolytic disease in which IgM fixes complement causing direct intravascular haemolysis (also known as cold agglutinins)
64
Which type of antibody is associated with warm autoimmune haemolytic anaemia?
IgG - extravascular haemolysis
65
Which type of antibody is associated with cold autoimmune haemolytic anaemia?
IgM - intravascular haemolysis
66
What are causes of cold autoimmune haemolytic anaemia?
1) Idiopathic 2) Post-infectious haemolytic anaemias - occurring 2-3 weeks after infection e.g. EBV, mycoplasma
67
What are examples of acquired Coombs negative haemolytic anaemias (large group of diverse haemolytic disorders)?
1) Physical lysis of red cells e.g. malaria 2) Haemolytic uraemic syndrome (E. coli 0157:H7) 3) Infectious causes DIC (such as fulminant meningococcemia) 4) Microangiopathic haemolytic anaemia 5) Paroxysmal nocturnal haemoglobinuria
68
What are the clinical features of microangiopathic haemolytic anaemia?
1) Microangiopathic haemolytic anaemia is an intravascular haemolytic disorder caused by physical lysis of red cells by deposited fibrin strands, resulting in the presence of schistocytes (fragments of red blood cells) on the blood film 2) It may be isolated, or occur in association with a thrombotic microangiopathy syndrome (such as haemolytic uraemic syndrome and thrombotic thrombocytopenia purpura), or in severe cases, disseminated intravascular coagulation
69
What condition would show schistocytes on blood film?
Microangiopathic haemolytic anaemia
70
What are the clinical features of paroxysmal nocturnal haemoglobinuria?
1) Rare acquired stem cell disorder of unknown aetiology 2) An abnormal surface glycoprotein expressed on a subclone of red blood cells marks these cells for complement mediated haemolysis – severity depends on the size of this subclone 3) Patients present in early adulthood with nocturnal episodes of intravascular haemolysis (it is not known why this occurs at night), and may be associated with other stem cell defects and increased risk of thrombosis (via an effect on complement mediated platelet aggregation) 4) Diagnosis is with flow cytometry
71
In which conditions can physical lysis of RBCs occur?
1) Falciparum malaria 2) Babesiosis - diseases in which the parasite grows in the red cell cytoplasm 3) In patients with prosthetic heart valves
72
What is amyloidosis?
A group of conditions caused by the deposition of extracellular insoluble fibrins in organs and blood vessels
73
What are the two types of amyloidosis?
1) Primary - idiopathic/spontaneous 2) Secondary - caused by underlying disorders
74
What causes amyloidosis?
The deposition of monoclonal light chains (from abnormal plasma cells) in tissues
75
Which conditions is secondary amyloidosis associated with?
Multiple myeloma or Waldenstrom's macroglobulinaemia
76
How do patients with amyloidosis present?
Features affecting multiple organs: 1) Nephrotic syndrome/renal failure (kidney) 2) Macroglossia, malabsorption or hepatosplenomegaly (GI) 3) Neuropathies (neuro) 4) Periorbital purpura (racoon eyes) - vasculature 5) Painful asymmetrical large joint inflammation (joints)
77
How is amyloidosis diagnosed?
Tissue biopsy (often from the rectum)
78
What is seen on tissue (rectal) biopsy in amyloidosis?
Apple-green birefringence when stained with Congo red and viewed under polarised light
79
What stain is needed to diagnose amyloidosis on biopsy?
Congo red
80
What is seen when amyloidosis tissue is stained with Congo red and viewed under polarised light?
Apple-green birefringence