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Meeran Haem Flashcards

1
Q

Name the causes of microcytic anaemia

A

Thalassaemia
Anaemia of chronic disease
Iron deficiency anaemia
Lead poisoning (basiphilic stippling)
Sideroblastic anaemia

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2
Q

What is aplastic anaemia and how does it present on a blood count?

A

Aplastic anaemia is caused by bone marrow failure resulting in pancytopenia and hypocellular bone marrow. 80% is idiopathic, 10% is primary (dyskeratosis congenita and fanconi anaemia) and 10% is secondary (viruses, SLE, drugs, radiation). It is caused by CD8+/ HLA-DR+ T cell destruction of bone marrow resulting in fatty changes.

Blood results will show reduced Hb, reticulocytes, neutrophils, platelets and bone marrow cellularity with raised MCV - the macrocytosis is due to the release of fetal haemoglobin in order to comepnsate for reduced red cell production

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3
Q

What would iron studies in iron deficiency anaemia show?

A

Low serum ferritin and Fe
Raised TIBC and transferrin

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4
Q

What is anaemia of chronic disease and how does it present in laboratory studies?

A

It occurs in chronic infection and inflammation e.g. TB, rheumatoid arthritis, IBD and malignancy.

It is mediated by IL-6 produced by macrophages which induces hepcidin production in the liver. Hepcidin works by retaining iron in macrophages (reduced delivery to RBCs for erythropoiesis) and reduces export from enterocytes (reduced plasma iron levels).

Lab findings would show microcytic hypochromic anaemia, rouleaux formation (increased plasma proteins), raised ferritin (acute phase protein) and reduced serum iron and TIBC

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5
Q

What differentiates megalobastic anaemia from non-megaloblastic macrocytic anaemia?

A

There are hypersegmented neutrophils in megaloblastic anaemia

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6
Q

What type of anaemia does blood loss cause?

A

Normocytic anaemia - due to reduced number of circulating RBCs

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7
Q

What type of anaemia does chronic alcohol consumption cause?

A

Non-megaloblastic macrocytic anaemia.

A poor diet in these patients cause further lead to folate and B12 deficiency which exacerbates this anaemia

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8
Q

What type of anaemia does chronic renal failure cause?

A

Normocytic normochromic anaemia - due to reduced production of RBCs due to diminished secretion of erythropoietin by damaged kidney cells

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9
Q

What type of anaemia does lead poisoning cause?

A

Microcytic anaemia due to dysfunctional haem synthesis.

We see basophilic stippling which reflects RNA found in RBCs due to defective erythropoiesis

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10
Q

What is autoimmune haemolytic anaemia (AIHA)?

A

It is the destruction of RBCs in the spleen after being bound by autoantibodies. Direct antiglobulin test (DAT) is positive and spherocytes are present on blood film

AIHA is classified as warm or cold

Warm - IgG, binds to RBCs at 37ºC. Caused by lymphoproliferative disorders, drugs (e.g. penicillin) and autoimmune diseases (e.g. SLE)

Cold - IgM, binds to RBCs <4ºC. Caused usually after an infection by mycoplasma and EBV

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11
Q

What is Glucose-6-phosphate dehydrogenase (G6PD) important for?

A

It is an essential enzyme in the RBC pentose phosphate pathway - it maintains NADPH levels whin supply glutathione to neutralise free radicals that may have otherwise caused oxidative damage.

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12
Q

What are G6PDD patients at risk of?

A

Oxidative crises which can be precipitated by certain drugs (primaquine, sulphonamide, aspirin, trimethoprin and nitrofurantoin), fava beans and henna.

These attacks result in haemolytic anaemia with jaundice and a blood film will show bite cells and Heinz bodies

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13
Q

What are causes of microangiopathic haemolytic anaemia (MAHA)?

A

It is caused by the mechanical destruction of RBCs. Causes include:
* Thrombotic thrombocytopenic purpura (TTP)
* Haemolytic uraemic syndrom (HUS)
* Disseminated intravascular coagulation (DIC)
* Systemic lupus erythematous (SLE)

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14
Q

What is the pathophysiology of sickle cell anaemia?

A

It is autosomal recessive condition where there is a point mutation in the beta-globulin chain of haemoglobin (chromosome 11) - substitutes glutamic acid at position 6 for valine

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15
Q

What are hereditary spherocytosis and hereditary eliptocytosis?

A

These are autosomal dominant disorders that result in RBC membrane defects and extravascular haemolysis

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16
Q

What is paroxysmal nocturnal haemoglobinuria (PNH)?

A

Rare stem cell disorder which results in intravascular haemolysis, haemoglobinuria (especially at night) and thrombophilia. Ham’s test is positive.

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17
Q

What are howell-jolly bodies?

A

They are nuclear DNA remnants found in circulating erythrocytes.

Usuually healthy erythrocytes expel these DNA fragments and those with Howell-Jolly bodies are removed by the spleen.

Common causes of Howell–Jolly bodies include splenectomy secondary to trauma and autosplenectomy resulting from sickle cell disease.

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18
Q

What are tear-drop cells?

A

These are also known as dacrocytes, caused by myelofibrosis - the bone marrow undergoing fibrosis, usually following a myeloproliferative disorder such as polycythaemia rubra vera or essential thrombocytosis.

Bone marrow production of blood cells decreases resulting in a pancytopenia. The body compensates with extra-medullary haemopoiesis causing hepatosplenomegaly.

Blood film will demonstrate leuko-erythroblasts, tear-drop cells and circulating megakaryocytes. Bone marrow aspirate is described as a ‘dry and bloody’ tap.

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19
Q

What are cabot rings?

A

They are looped structures found within erythrocytes which can be caused by megasloblastic anaemia.

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20
Q

What is rouleaux formation?

A

Commonly seen in multiple myeloma, it is the stacks of erythrocytes that form in high plasma protein states

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21
Q

What are target cells?

A

Erythrocytes with a central area of staining, a ring of pallor and an outer ring of staining.

They are formed in thalassaemia, asplenia and liver disease.

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22
Q

What are pappenheimer bodies?

A

Granules of iron found within erythrocytes.

Causes include lead poisoning, sideroblastic anaemia and haemolytic anaemia.

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23
Q

What type of hypersensitivity reaction is immune thrombocytopenic purpura (ITP)? Acute and Chronic

A

Acute ITP is a type 2 hypersensitivity reaction where IgG binds to viral-coated platelets. This precedes a viral illness approximately 2 weeks prior, and is self-limiting.

Chronic ITP is gradual in onset with no hx of previous viral infection. It is also a type 2 hypersensitivity reaction with IgG targeting GLP-2b/3a

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24
Q

What can cause disseminated intravascular coagulation (DIC)?

A

Gram-ve sepsis
Malignancy
Trauma
Placental abruption
Amniotic fluid embolism

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25
What is the pathophysiology of disseminated intravascular coagulation (DIC)?
Tissue factor is released which triggers the activation of the clotting cascade, leading to platelet activation (thrombosis in microcirculation) and fibrin deposition (haemolysis). The consumption of platelets and clotting factors predisposes to bleeding. Plasmin is also generated in DIC which causes fibrinolysis, perpetuating the bleeding risk. The clinical manifestations of DIC are therefore linked to microthombus production (renal failure and neurological signs) and reduced platelets, clotting factors and increased fibrinolysis (bruising, gastrointestinal bleeding and shock).
26
What is hereditary haemorrhagic telangiectasia?
It is also known as Osler-Weber-Rendu syndrome and is an autosomal dominant condition characterized by telangiectasia formation on the skin and mucous membranes leading to nose and gastrointestinal bleeds.
27
What is prothrombin G20210A mutation?
It is an inherited thrombophilia caused by the substitution of guanine with adenine at the 202010 position of the prothrombin gene. This amplified prothrombin production, increasing the risk of clotting and causing a predisposition to DVTs and PEs. *Physiologically, prothrombin promotes clotting after a blood vessel has been damaged.
28
What is Factor V Leiden?
It is an autosomal dominant inherited thrombophilia. Normally protein C inhibits factor V. However in Factor V Leiden, a mutation to the F5 gene swaps arginine for glutamine, resulting in an impairment of degradation of factor V by protein C. Hence these patients are at risk of DVTs and miscarriages
29
What are the common presentations of antiphospholipid syndrome?
Stroke (arterial thrombosis) DVTs (venous thrombosis) Miscarriages
30
What is Buerger's disease?
Also known as thromboangitis obliterans. It is a vasculitis of small/medium arteries and veins of the hands and feet. It is strongly related to smoking. First presentation is claudication however as the disease progresses it leads to gangrene and amputation in severe cases. Angiogram will show a corckscrew appearance of the arteries
31
What is protein S deficiency?
It is associated with impaired degradation of factors Va and VIIIa. This leads to persistence of factors Va and VIIIa in the ciruclation so increased susceptability to venous thrombosis. Three types: * Type I (quantitative defect) - decreased levels of total protein S * Types II (qualitative defect) - normal total levels, decreased function * Type III (qualitative defect) - normal total levels, decreased free protein S, decreased function *Protein S is a vitamin K dependent anticoagulant so warfarin treatment and liver disease will increase venous thrombosis in rarer cases.
32
What is antithrombin deficiency?
Inherited cause of venous thrombosis. Under physiological conditions antithrombin inhibits clotting factors thrombin and factor 10a.
33
What are the clinical features of fluid overload transfusion?
Dyspnoea Distended neck veins Pink frothy sputum *Patients with pre-existing cardiac or renal failure are prone to fluid overload
34
What is graft versus host disease (GVHD)?
It occurs due to the transfer of donor lymphocytes to the recipient in a blood transfusion in immunosuppressed patients. Normally, the immune system is strong enough to detect and destroy donor lymphocytes. However, in immunosuppression (stem cell transplant patients / chemotherapy / malignancy / HIV) the donor lymphocytes cannot be destroyed; these foreign lymphocytes persist and target host tissue, especially the gastrointestinal tract and skin. Symptoms include: diarrhoea maculopapular rash skin necrosis *To minimise GVHD, irradiation of blood is done
35
What does IgA defieicny lead to?
It causes recurrent mild infection of the mucous membranes lining the airways and digestive tract. Serum IgA levels are undetectable but IgG and IgM are normal. IgA is found in mucous secretions from the respiratory and gastrointestinal tracts and plays a key role in mucosal immunity. IgA deficient patients are also predisposed to severe anaphylactic reactions to blood transfusions due to the presence of IgA in donor blood.
36
What is transfusion-related lung injury (TRALI)?
TRALI is an acute non-cardiogenic pulmonary oedema that occurs within 6 hours of a blood transfusion. Pathogenesis involves the presence of anti-white blood cell antibodies in the donor blood that attacks host leukocytes. This is due to previous sensitising events in donors which include previous blood transfusion or transplantation. Clinical features are dry cough, dyspnoea and fever
37
What are the clinical signs of immediate haemolytic transfusion reaction?
Abdominal pain, loin pain, facial flushing, vomiting and haemoglobinuria. It is due to ABO incompatibility and occurs 1-2hours post-transfusion. The most severe reaction occurs if a group O patient is transfused with group A blood.
38
What is hairy cell leukaemia?
Malignancy of B lymphocytes, and a subtype of chronic lymphocytic leukaemia. It is common in middle-aged men. On microscopy of tumour cells, you see fine hair-like projections. Cell surface markers include CD25 (IL-2 receptor) and CD11c (adhesion molecule). Diagnosis is confirmed by the presence of tartate-resistant acid phosphatase (TRAP) on cytochemical analysis. Clinica features are splenomegaly, hepatomegaly and pancytopenia
39
What is adult T-cell leukaemia?
Caused by human T-cell leukaemia virus type 1 (HTLV-1). It is endemic in Japan and the Carribean. It has a poor prognosis Tumour cells express the cell surface protein CD4 and will contain the HTLV-1 virus within; the nuclei of ATL cells have a characteristic cloverleaf appearance. Clinical features include lymphadenopathy, hepatosplenomegaly, skin lesions and hypercalcaemia.
40
What is large granular lymphocytic leukaemia?
There is a presence of large lymphocytes in the blood stream and bone marrow that contain azurophilic granules
41
What causes Burkitt's lymphoma and waht are they associated with?
It is caused by latent Epstein-Barr virus (EBV) infection and highly associated with translocations of the c-myc gene on chromosome 8
42
What is the pathogenesis of Hodgkin's lymphoma?
It is caused by the proliferation of B cells from the germinal centre. The pathogenesis is linked to EBV infection which activates NF-κB, preventing apoptosis of infected cells. Release of IL-5 from B-cells activates eosinophils, prolonging the life of B cells further.
43
What causes mantle cell lymphoma?
It is an aggressive B-cell lymphoma primarily in elderly men. It is associated with t(11;14) involving the BCL-1 locus and Ig heavy chain locus --> leads to over-expression of cyclin D1.
44
What causes follicular lymphomas?
It is caused by t(14;18) which leads to over-expression of BCL-2 protein --> inhibition of apoptosis which promotes survival of tumour cells. Tumour cells are characterized by centrocytes (small B cells with irregular nuclei and reduced cytoplasm) and centroblasts (larger B cells with multiple nuclei).
45
What is diffuse large B-cell lymphoma (DLBL)?
It is characterised by large lymphocytes which have a diffuse growth pattern - commonly affecting the elderly. Also linked to t(14;18) suggesting that follicular lymphomas can undergo transformation to cause DLBL. Two subtypes: * Deficiency-associated large B-cell lymphoma (linked to latent EBV infection) * Body cavity-based large cell lymphoma (linked to HHV8 infection)
46
What is small lymphocytic lymphoma?
It is indistinguishable from CLL in terms of genetics and morphology, though presents with a greater number of peripheral blood lymphocytosis
47
What is mycosis fungoides?
It is a cutaneous T-cell lymphoma most common in elderly men. It presents with rash-like lesions similar to eczema or psoriasis
48
What are the clinical features of essential thrombocythaemia (high platelet count)?
Bleeding events - GI bleeding, bruising, petechiae, menorrhagia Thrombotic events - erythromelalgia (erythema, swelling, pain, burning sensation in extremities), digital ischaemia, CVA, DVT, Budd-Chiari syndrome
49
What is the treatment for essential thrombocythaemia?
hydroxyurea or anagrelide
50
What would blood test and bone marrow show in essential thrombocythaemia?
Blood tests: platelet count >600x10^9/L Bone marrow: hypercellular with giant platelets, megakaryocyte clustering and hyperplasia
51
WHat is the pathophysiology of myelofibrosis?
Cause is unknown but thought to be related to abnormal megakaryocytes releasing PDGF and TGF-β which stimulate fibroblast proliferation
52
What do blood tests, blood film and bone marrow aspirate show in myelofibrosis?
Blood test: initial raise in WCC and platelets during the compensatory phase - as fibrosis progresses, both are lowered. Blood film: leukoerythroblastic, with tear-drop cells and circulating megakaryocytes (fibrosis causes ejection of megakaryocytes from the bone marrow) Bone marrow aspirate - "dry" or bloody tap
53
What is the diagnostic criteria for multiple myeloma?
Paraprotein bands of >30g/L on electrophoresis *Bence-Jones proteins (Ig light chains) may be present in the urine *X-ray may show punched-out lesions
54
What is chronic myelo-monocytic leukaemia (CMML)?
Myelodysplastic/ myeloproliferative disease which most commonly affects the elderly population Defined by a monocytosis of >1000/mm3 and increased number of monocytes in the bone marrow. Myeloblasts make up <5% of the peripheral blood and <20 per cent of the bone marrow. Eosinophilia may be present in CMML associated with a t(5;12) trans- location.
55
What is polycythaemia rubra vera and what causes it?
It is the proliferation of erythoid, granulocytic and megakaryocytic lines. Most commonly due to V167F mutation on exon 2 of the JAK2 gene, causing uncontrolled stem cell proliferation. Erythropoietin levels are low due to a -ve feedback response from increased erythrocyte production
56
What are the clinical features of polycythaemia rubra vera?
Hyperviscosity (headaches, dizziness and stroke) Hyper-mast-cell degranulation (pruritis after hot baths, plethoric skin and peptic ulceration) Increased cell turnover (gout).
57
What is refractory anaemia? What types are there?
Refractory anaemia = <5% myeloblasts present in the bone marrow With ringed sideroblasts = <5% myeloblasts present in the bone marrow but >15% erythrocyte precursors stuffed with iron in their mitochondria With excess blasts: Type 1 = 5–9%myeloblasts in the bone marrow Type 2 = 10–19% myeloblasts in the bone marrow
58
What is 5q-syndrome?
It is the deletion of the long arm of chromosome 5. Features include hypo-lobulated megakaryocytes and an increased/ normal platelet count.
59
What is the common blood abnormality in sarcoidosis?
Monocytosis - contributory to the pathogenesis of granulomatous disease
60
What conditions cause monocytosis?
Sarcoidosis Brucellosis Typhoid Varicella zoster infection Chronic myelo-monocytic leukaemia
61
What are casues of secondary polycythaemia?
Hypoxia: * High altitude * Smoking * Lung disease * Cyanotic heart disease Renal disease: * Cysts * Renal artery stenosis * Hydronephrosis Solid tumours: * Renal cell carcinoma * Hepatocellular carcinoma
62
What are causes of eosinophilia?
Allergic disease: * Asthma * Rheymatoid arthritis * Polyarteritis Neoplasms: * Hodgkin's lymphona * Non-Hodgkin's lymphoma Drugs (e.g. NSAIDS) Parasites
63
What causes a leuko-erythroblastic picture on blood film?
Miliary tuberculosis Myelofibrosis Leukaemia Lymphoma Non-haematopoietic cancers (e.g. breast cancer)
64
What are causes of neutrophilia?
Caused by tissue inflammation like: acute pancreatitis, ulcerative colitis and corticosteroids
65
What is the most severe form of ABO incompatability?
If group A red cells are transfused to a group O patient
66
Which antibodies are the most frequent causes of delayed haemolyitc transfusion reactions?
Kidd (Jk) and Rh antibodies
67
What is hereditary spherocytosis?
Autosomal dominant inherited haemolytic anaemia - fragility of RBCs due to dysfunctional skeletal proteins (spectrin, ankyrin and band 4.2) A blood film will show spherocytes and reticulocytes Coombs test will be negative Osmotic fragility test will be positive (though only confirms spherocytes not the cause!)
68
What will a blood film of hyposplenism show?
Howell-Jolly bodies - small fragments of non-functional nuclei in RBCs Target cells - central dense area with a ring of pallor Occasional nucleated RBCs Lymphocytosis Macrocytosis Acanthocytes (spur cells) - spiculated red cells
69
What conditions cause target cells?
3 Hs * Hepatic pathology * Hyposplenism * Haemoglobinopathies
70
What conditions cause acanthocytes?
Hyposplenism alpha-beta-lipoproteinaemia Chronic liver disease alpha-thalassaemia trait
71
In which haematological diseases will a splenectomy be useful for?
**Th**e **PIIES** Thalasaemia Pyruvate kinease deficiency Immune haemolytic anaemia Idiopathic thrombocytopenic prupura Elliptocytosis Spherocytosis (hereditary)
72
What is paroxysmal cold haemoglobinuria?
AIHA precipitated by cold temperatures - causing sudden haemoglobinuria and jaundice Donath-Landsteiner antibodies (IgG autoantibodies) form after an infection --> bind to RBC surface antigens in the cold --> complement-mediated haemolysis
73
What is paroxysmal nocturnal haemoglobinuria?
**PNH** Pancytopenia (aplastic anaemia) New thrombus Haemolytic anaemia (especially overnight due to built up acidosis) Diagnose with a flow cytometry Treatment: thromboprophylaxis and eculizumab (monoclonal antibody) *Thrombosis is linked to Budd-Chiari syndrome
74
How does subacute combined generation of the spinal cord present?
Symmetrical loss of dorsal columns - loss of touch and proprioception leading to ataxia and LMN signs Corticospinal tract lsos - leading to UMN signs Sparing of temperature and pain sensation - carried by spinothalamic tracts *Can also present with falls (as a consequence of optic atrophy is B12 deficiency)
75
What is the most sensitive antibody for pernicious anaemia?
Anti-parietal cell antibodies *Anti-intrinsic factor antibodies are not as sensitive as the anti-parietal cell antibodies
76
What are primary causes of aplastic anaemia?
Congenital - Fanconi's anaemia Idiopathic acquired aplastic anaemia
77
What are secondary causes of aplastic anaemia?
Drugs (all the Cs): cytotoxics, carbamazepine, chloramphenicol anticonvulsants (e.g. phenytoin) Ionising radiation Viruses (hepatitis, EBV)
78
What is combined polycythaemia?
aka Smoker's polycythaemia Cigarettes contain high levels of carbon monoxide which displaces oxygen in haemoglobin --> increase in EPO --> increase RBC mass Smokers also have a reduced plasma volume *Both above togeher increase the relative concentration of Hb
79
What causes platelet aggregation with von WIllebrand Factor?
Ristocetin - will not bind if vWF is defective Collagen - will still aggregate if vWF is defective Fibrinogen - will still aggregate if vWF is defective
80
When can desmopressin be used in vWD?
In mild vWD (type 1 or 2) Desmopressin acts to increase vWF and FVIII concentration by releasing it from endothelial cell storage sites

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