Week 5 - WBC Disorders

Question 1

Differentiate between specific and non-specific immunity.

Answer 1

• Non-specific immunity: granulocytes/polymorphonuclears (polymorphic nuclei - irregular shape).

• Neutrophils.
• Eosinophils.
• Basophils.

• Specific immunity: non-granular/mononuclears

• Monocyte.
• Lymphocyte.

Question 2

Outline WBCs in health and disease.

Answer 2

Physiologic:
• Infancy/aged - lymphocytes increased.
• Pregnancy - leucocytes increased.

Non-neoplastic
• Reactive (common clinically):
- Leukocytosis increased.
- Leukocytopenia/pancytopenia.
- Agranulocytosis/neutropenia.
- Leukemoid reaction.
- Leukoerythroblastic reaction.
• Congenital (rare):
- Number and function disorders.

Neoplastic
• Pre-malignant:
- MPD - myeloproliferative disorders.
- MDS - myelodysplastic syndrome.
• Malignant:
- Leukaemia.
- Lymphoma.
- Myeloma.

Question 3

Differentiate between ‘philias’ and ‘penias’

Answer 3

‘Philias’ - relative increase in number of WBCs:
• Neutrophilia - bacterial sepsis.
• Lymphocytosis - viral, immune.
• Eosinophilia - allergy, parasites.

‘Penias’ - relative decrease in number of WBCs:
• Neutropenia, lymphopenia, eosinopenia, pancytopenia (all cells).
• Due to viral infections, drugs, radiation, chemotherapy etc.

Question 4

Outline neutrophilia.

Answer 4

• Neutrophilia: increased neutrophils - acute infection/inflammation.
• Commonest clinically - all types of acute infections, inflammation, bacterial, trauma → increased neutrophils.
• Infection.
• Trauma, tissue destruction.
• Some malignancies.
• Corticosteroids.
• Physiologic stress, physical agents.
• Metabolic disorders.

Question 5

What is a left shift?

Answer 5

• Left shift: immature neutrophils in blood - severe infection/inflammation.
• Increased neutrophilia + increased immature forms (band forms + myeloid cells).
• In the bone marrow, normal stem cell goes through various stages of maturation to form neutrophils → released into blood.
• In case of left shift, immature forms are released - usually suggests that there is increased need for these neutrophils.

Question 6

Identify toxic changes.

Answer 6

1. Toxic granulations.
2. Dohle bodies - pale blue inclusions.
3. Vacuolation.

• Acute infection, trauma etc. ‘Retention of primary granules of blasts - suggestion of early release from marrow.’

Question 7

Outline lymphocytosis.

Answer 7

• Increased lymphocytes: small, round, large nucleus, little cytoplasm.
• Causes: viral, chronic infections, immune reactions, bacterial (Pertussis, TB) etc.
• Viral infections.
• Some fungal, parasitic infections.
• Rare bacterial infections.
• Drug sensitivity.
• Immunologic disease.

Question 8

What is reactive lymphocytosis?

Answer 8

• Atypical/reactive/virocytes: activated T lymphocytes. Large, more cytoplasm, flowing between RBC. Viral infections. EBV (infectious mononucleosis).

• Specific type of lymphocytosis where there are activated T lymphocytes - large cells, clear cytoplasm, very large fragile cells flowing inbetween RBC.
• Usually seen in viral infections and specifically infectious mononucleosis due to EBV.

Question 9

Outline eosinophilia.

Answer 9

• Increased eosinophils: eosinophilic granules, bilobed nucleus.
• Causes: allergy, hypersensitivity, hay fever, asthma, parasites, worm infestations and Hodgkins lymphoma.
• Basophilia is very rare - if present, suspect CML.
• Hypersensitivity reactions.
• Drug therapy.
• Pulmonary disease.
• Parasitic infection.
• Myeloproliferative disease.

Question 10

What is a leucoerythroblastic reaction?

Answer 10

• Leucoblasts and erythroblasts in blood.
• Release all types of immature cells from bone marrow.
• Seen in marrow disorders such as marrow fibrosis, malignant infiltration, severe hyperplasia or infection.
• Release of immature cells of both WBCs and RBCs into the blood.
• Release of all types of immature cells from the marrow - usually due to marrow fibrosis, malignancy, metastasis, severe hyperplasia, severe infection causing excess stimulation of bone marrow → both cells released into blood.

Question 11

What is a leukaemoid reaction?

Answer 11

• Very high WBC counts: severe and excessive leucocytosis with immature cells (leukaemia like).
• Causes:
- Severe infections (usually children).
- Severe haemolytic anaemia/crisis.
- Marrow infiltrations, metastasis (leucoerythroblastic reaction).

• Markedly increased counts may or may not be with immature cells - differentiate to leucoerythroblastic reaction.
• Looks like leukaemia when observing blood count - microscopically see normal immature and mature cells.
• Severe and excessive leucocytosis with immature cells.
• If immature cells are more - it is also a leucoerythroblastic reaction.

Question 12

Outline neutropenia and agranulocytosis.

Answer 12

• Neutropenia: low neutrophils.
• Agranulocytosis: severe + infections (severe neutropenia and patient having life threatening infections. Serious condition clinically).
• 2 major causes:
- Decreased production - marrow failure.
- Increased destruction - immune (Abs destroy neutrophils), splenomegaly, septicaemia, viral (HBV - can suppress BM).

• Simple neutropenia is <1.5 and agranulocytosis is <0.5. Clinical features are more important.

Question 13

Outline pancytopenia.

Answer 13

• Decreased RBC, WBC and platelets (all cell lines decreased).
• Causes:
- Bone marrow suppression.
- Megaloblastic anaemia.
- Aplastic anaemia.
- Myelodysplastic syndromes.

Question 14

What is reactive lymphadenitis?

Answer 14

• Enlarged lymph nodes (lymphadenopathy) due to some reaction to infection or inflammation.
• Can be enlargement or severe enlargement with abscess formation.

Clinical:
• Enlarged, tender/painful.
• Mobile (not fixed).
• Associated with inflammation in the area.

Microscopy:
• Hyperplasia of follicles.
• Sinus histiocytosis.
• Granuloma in TB.
• Abscess in bacterial/cat-scratch disease.

• Microscopically, plenty of tingible body macrophages - macrophages that are eating away the unwanted lymphocytes. Because there is maximal proliferation of lymphocytes, the lymphocytes that are not specific for that particular infection or allergen/antigen will be destroyed by apoptosis.
• Reactive lymph nodes:
• Germinal centre (follicle).
• Mantle zone.
• Prominent macrophages.

Question 15

Outline haematologic neoplasms.

Answer 15

• Neoplastic disorders of the haemopoietic system. Clinically known as haemato-oncology (complex field).
• 2 major groups of neoplasms - myeloid and lymphoid.

Myeloid neoplasms:
• Acute myeloid leukaemia (AML) - neoplastic blast cells without maturation (all very immature).
• Myeloproliferative disorders (MPD) - neoplastic blasts mature along one or more cell lines (increased cells) - CML.
• Myelodysplastic syndromes (MDS) - blasts mature in dysplastic way - destruction → BM increased, blood decreased.

Lymphatic neoplasms:
• Lymphatic leukaemia - acute (ALL), chronic (CLL), myeloma.
• Lymphoma - Non-Hodgkins (NHL), Hodgkins (HL).

• Lymphatic - leukaemia/lymphoma.
• Classification of haematologic neoplasms is very complex - hundreds of subtypes.

Question 16

Outline leukaemia.

Answer 16

• Malignancy of white blood cell progenitor (blast) cells in bone marrow which spreads to blood.

• Replacement bone marrow by leukaemic cells ∴ decrease other cell types.
• Infiltration of organs (e.g. liver, spleen, lymph nodes) and blood with abnormal WBC.

Question 17

Outline the aetiology of leukaemia.

Answer 17

• Primarily unknown but risk factors include ionising radiation, viral infection, cytotoxic drugs, genetic, immunological.

Question 18

Describe the pathogenesis of leukaemia.

Answer 18

• Oncogenesis - mutations - increased division, decreased differentiation. Chromosomal (genetic) mutations that affect cell division leading to uncontrolled cell division with decreased differentiation.

• DNA damage causes mutations (activation of oncogenes or inhibition of tumour suppressor genes).
• Oncogenic mutations inhibit differentiation → accumulation immature blasts in bone marrow.
- Release blasts into the blood + bone marrow failure.
- Decreased production mature WBC/RBC/platelets.
N.B. In chronic leukaemia, is accumulation of more differentiated progenitor cells.

Question 19

Identify the clinical features/morphology of leukaemia.

Answer 19

Clinical features:
• Typical features of leukaemia dependent on different types.
• Decreased haemopoiesis (bone marrow infiltrated by malignant cells).
- Anaemia (due to low RBC).
- Fever - infections (due to low WBC).
- Increased bleeding tendency (due to low platelets).
• Organ infiltration
- Bone pain/back pain/fractures, lymphadenopathy, hepatosplenomegaly (due to leukaemic infiltration).
- Cancer cells infiltrate into the bone marrow, liver, spleen and lymph nodes (haemopoietic tissues). Malignancy only spreads to these tissues initially, can spread to other tissues later (less common).

Morphology:
• Presence of increased immature cells in blood + decreased differentiated cells.

Question 20

What are the subtypes of leukaemia?

Answer 20

There are 4 main types of leukaemia:

1. Acute myeloid leukaemia (AML) – M0-M7.
2. Acute lymphoid leukaemia (ALL) – L1, L2, L3.
3. Chronic myeloid leukaemia (CML) – Eosinophilic, Neutrophilic, Myelomonocytic.
4. Chronic lymphoid leukaemia (CLL) – Hairy cell leukaemia, prolymphoic, sezary syndrome.

• Many subtypes - gene specific diagnosis and therapy. Treatment is targeted at the specific abnormalities in patients (personalised medicine).

Question 21

How do the mutations in leukaemia transform to clinical presentation?

Answer 21

• Mutations stimulate increased growth → leads to increased self renewal (cell division) and lack of cell differentiation. Therefore, no function and continuous cell division → cancer.
• All due to different genetic mutations. Common oncogenes that are mutated include:
- CML - BCR-ABL.
- AML - RARA.
- ALL - BCL2.
- MPD - JAK2.

Question 22

Outline the classification of leukaemia.

Answer 22

• FAB classification - simplified version - acute and chronic leukaemia.
• Stem cells give rise to 2 types of blasts:
- Myeloblasts → myeloid leukaemia (acute + chronic).
- Lymphoblasts → lymphoid leukaemia (acute + chronic).

• AML

• M0 (totally undifferentiated) to M7 (megakaryoblastic leukaemia).
• Varying grades of differentiation.
• M3 most common (promyelocytic leukaemia).

• ALL

• Also differ in regards to amount of differentiation.
• L1 most common - small monomorphic leukaemia.

• Chronic Leukaemia

• CML.
• CLL (most common clinically).
• Both later age, chronic presentation.
• Asymptomatic for many years (many patients unaware they have a problem).
• Slow and gradual progression.

Question 23

Outline acute lymphoblastic leukaemia (ALL).

Answer 23

• AKA lymphocytic.
• Accumulation of immature B and T lymphoid cells (e.g. lymphoblasts). 80% are due to pre-B cells (B-ALL) which are CD10 +ve.
• Any age, common in children (<10 years).
• FAB classification L1, L2 and L3.
• L1 most common - CD10 +ve (pre B lymphocytes) - immature B cell marker.
• Present with growth failure, fever, anaemia, lymphadenopathy* (very prominent), bleeding*
• Minimal hepatosplenomegaly (because lymphoblasts go more into lymph nodes).
• Mediastinal lymphadenopathy.

Microscopy:
• Plenty of large round blast cells with little blue cytoplasm, no granules in cytoplasm - lymphoblasts.
• Large lymphocyte like cells - normal lymphocyte is around the size of an RBC, lymphoblasts are larger - look like lymphocytes but they are blast cells, scanty cytoplasm.
• Lymphoblasts have dense chromatin, few nucleoli, scanty cytoplasm, no cytoplasmic granules.

Question 24

Outline acute myeloid leukaemia (AML).

Answer 24

• Adults 40-60y common.
• Neoplastic blasts in BM, blood, liver, spleen.
• Commonest is M3.
• Anaemia, fever, bleeding.
• Hepatosplenomegaly* moderate (leukaemic infiltration).
• No significant lymphadenopathy (can be there but not significant).
• Gum hypertrophy* (leukaemic infiltration).
• Increased infections - candidiasis (oral thrush - fungal), chronic infections also common (decreased WBC).
• Gingivitis and hyperplasia.
• Bruising - purpura (decrease platelets).

Microscopy:
• Plenty of large round blast cells with more clear cytoplasm with granules and Auer rods - myeloblasts.
• The same large blast cells but have more clear cytoplasm with plenty of granules. The granules may join to form crystal like structures within the cytoplasm known as Auer rods.
• Myeloblasts have fine lacy chromatin, many nucleoli, more cytoplasm, cytoplasmic granules.

Question 25

Outline AML-M4 and AML-M7.

Answer 25

AML-M4 - Myelomonocytic leukaemia
• Some cells with pink cytoplasm and some cells with blue cytoplasm.
• Blue cytoplasm - monoblast.
• Pink cytoplasm - myeloblast.
• All immature cells - leukaemia M4 type.

AML-M7 - Megakaryocytic leukaemia
• Blasts, abnormal megakaryocytes, plenty of abnormal giant platelets.
• Plenty of platelets and megakaryocytes in the blood film apart from these blasts.
• Megakaryoblastic leukaemia - AML-M7.

N.B. There are other types - not common. Commonest is M3.

Question 26

Differentiate between ALL and AML.

Answer 26

ALL:
• Children, lymphadenopathy.
• Scanty cytoplasm.
• No granules.

AML:
• Adults, hepatomegaly.
• More cytoplasm.
• Granules + Auer Rods.

• Both have anaemia, fever, infections and bleeding as common features.
• Both leukaemias can occur at any age.

Question 27

Outline chronic lymphocytic leukaemia (CLL).

Answer 27

• Similar to SLL (small lymphocytic lymphoma) - Non-Hodgkins. (Similar clinically, pathogenesis and management. However, in leukaemia there are more lymphocytes in the blood, lymphoma - more in lymph nodes).
• Elderly age (>60), commonest leukaemia.
• Presents with anaemia, fever and bleeding - slow over years.
• Lymphocytosis and lymphadenopathy (CLL/SLL).
• Splenomegaly, mild hepatomegaly.
• Common - B cell (CD5 +ve), high BCL2 gene.
- Commonest is B cell type - carrying T cell antigen (CD5 +ve) - usually do this test in the lab to confirm that it is a leukaemia. High BCL2 gene expression.
• Hypogammaglobulinaemia (not functioning).
• Clinical phases:
- Chronic - slow progress - years (commonest - most commonly present in chronic phase).
- Accelerated phase - high grade lymphoma/leukaemia (at terminal phase after many years → can transform into a high grade lymphoma or acute lymphoblastic leukaemia - high mortality).

Microscopy:
• Plenty of normal looking lymphocytes and smudge/dead forms.
• Mature lymphocytes with scanty cytoplasm.
• Only characteristic feature seen is smudge cells - smeared out/crushed cells. Smear cells can be seen in many conditions but are very characteristic of CLL (because the cancer cells are fragile).
• Thrombocytopenia, pancytopenia are all very rare and late.

Question 28

Outline chronic myeloid leukaemia (CML).

Answer 28

• Middle age 40-60y.
• Philadelphia chromosome, t(9:22) - characterised by the Philadelphia chromosome - short 22 chromosome where it has lost a portion of its segment of chromosome to chromosome 9 (translocation).
• BCR-ABL fusion gene - oncogene.
- Activation of BCR-ABL fusion gene - oncogene → produces carcinogenesis - uncontrolled proliferation of blast cells. These blast cells mature into different forms of WBC - there will be basophils, eosinophils and neutrophils (more common) - mature cells of all types.
• Anaemia, fever and bleeding.
• Marked leucocytosis - >50 (DDx: leukaemoid reaction). Marked left shift.
• Marked hepatosplenomegaly.
• Clinical phases:
- Chronic - slow progress - years (commonest) - gradually develop weakness, fatigue, anaemia, infections, bleeding.
- Accelerated - rapid progress - months - rapid progression usually within months, blast cells increase.
- Blast crisis - acute leukaemia - weeks - all the blasts take over the space. No more mature cells (very few mature cells). Patients deteriorates within a week - very serious clinical condition like acute leukaemia - blast crisis of CML.

Microscopy:
• Marked increased in WBCs, marked shift to the left (very immature cells) with basophils.
• Increased numbers maturing myeloid cells (neutrophils, myelocytes, eosinophils, basophils) - increased progenitor cells but blasts make up less than 10% circulatory cells.

Question 29

Describe the Philadelphia chromosome.

Answer 29

• Activation of BCR-ABL fusion gene results due to the translocation of portion of the 22 to 9 chromosome resulting in a very small chromosome 22.
• This was the earliest detection of chromosome abnormalities in cancers.
• CML was the first case of leukaemia/cancer where a genetic abnormality was noted. Now there is targeted therapy for the BCR-ABL fusion gene → 80% cure rare now possible in CML - importance of understanding pathology/pathogenesis - can develop new treatments.

Question 30

Describe the progression of chronic CML to a blast crisis.

Answer 30

• Chronic phase of CML going on to a blast crisis. Difference is reducing mature cells and increasing immature cells (markedly increased blasts).

Question 31

Outline multiple myeloma.

Answer 31

• Leukaemia of plasma cells (B lymphocytes) - malignant proliferation of plasma cells (mature B lymphocytes) in bone marrow.
• Hypergammaglobulinaemia - mature B lymphocytes producing plenty of immunoglobulins.
• Monoclonal antibody peak - not useful.
• Thick viscous blood - infarctions, visual difficulties and even blindness - too many gamma globulins (thick sticky proteins) → makes the blood very viscous → leads to infarctions, visual difficulties and even blindness (obstruction to the small blood vessels) - very thick plasma because of increased gamma globulins.
• Disease of old age, males common.
• Multiple, punched out lytic bone lesions (osteolysis) and fractures - typically produce punched out bony lesions - looks like many holes all over the bones.
• Immunodeficiency - infections.

Question 32

Describe the aetiology and pathogenesis of lymphoma.

Answer 32

• Neoplasms of lymphoid tissue (leukaemia and lymphoma).

Aetiology:
• Idiopathic, genetic mutations, infective (EBV).

Pathogenesis (based on genetic mutation):
• Overexpression of anti-apoptotic gene (commonest).
- Normally, lymphocytes die during antigenic stimulation. Most of the lymphocytes which produce Abs that are not specific to the antigen that stimulated it → die. Only the lymphocytes that produce appropriate Ab to antigen survive.
- Normal immunity - whenever exposed to antigen, thousands/millions of lymphocyte proliferations producing varieties of antibodies → only those specific lymphocytes that produce Abs that bind with antigen survive. All others die by apoptosis.
- Abnormality of anti-apoptotic gene - instead of lymphocyte dying like normal → continues to proliferate - pathogenesis of commonest lymphoid neoplasms (neoplasms of lymphocytes).
• t(14;18) → BCL2 + IgM → B lymphocyte neoplasia.
- Commonest - BCL2 (often related to EBV infection) - translocation between chromosome 14 and 18. Commonest is B neoplasms. IgM receptor on cells, germinal centres of lymphocytes have already been committed to one type of Ab production (mature B lymphocytes of germinal centre).

• Often due to translocation between chromosomes 14 and 18 resulting in BCL2 gene.
• Results in over-expression of anti-apoptotic gene → malignant cells do not die → increase proliferation → neoplasm.

Question 33

Outline the classification of lymphoma.

Answer 33

• Complex classification of many different types of lymphomas - which also includes histiocytic lymphomas.
• Simplified version, many subtypes.
• Hodgkin’s lymphoma - neoplasia of B lymphocytes with ‘RS cells’ - characterised by the presence of specialised malignant cells known as Reed Sternberg cells.
• Non-Hodgkin’s lymphoma - neoplasia of lymphocytes, no ‘RS cells’ - complex, many subtypes. Includes leukaemia (ALL/CLL) or lymphoma or both. Langerhans cell histiocytoses.

Question 34

Identify the clinical features of lymphoma.

Answer 34

• Fever, anaemia, infections. Lymphadenopathy (malignant/neoplastic lymph nodes), splenomegaly.
• Bone marrow infiltration and bleeding only in high grade (only in high grade when involves bone marrow. Unlike leukaemia, bleeding not common in neoplastic malignant lymphomas).

Question 35

Outline the diagnosis and prognosis of lymphoma.

Answer 35

Diagnosis:
• Complex process.
• Immunophenotyping: T, B, CD5 (CLL) - immunophenotyping for markers of T lymphocytes, B lymphocytes and varieties of CD antigens (T and B antigens to differentiate between T and B cell lymphomas).
• Genetic: BCL2, TdT (in ALL) etc. - genetic markers.

Prognosis:
• Success story* responds to therapy - most lymphoid neoplasms including lymphomas and leukaemia are curable through advanced treatment options.
• Lymphomas can be classified as low grade, intermediate and high grade.
• Low grade lymphoma can transform to high grade lymphoma or leukaemia over the years.

Question 36

Identify the relative frequency of lymphoid malignancies.

Answer 36

• Majority of lymphomas clinically are NHL (~60% in various populations). Out of NHL - diffuse large B cell lymphoma from the stem cell is most common. Also includes other varieties of lymphomas e.g. mature T cell lymphomas and small lymphocytic lymphomas.
• MGUS - Monoclonal Gammopathy of Undetermined Significance AKA plasma cell disorders - includes myeloma (~16%).
• Clinically Hodgkin’s disease is less common compared to NHL (<10% clinically).
• ALL and CLL also apart of lymphoid malignancies.

Question 37

Outline Hodgkin’s lymphoma.

Answer 37

• Malignancy of GC cell → Reed Sternberg (RS) cell.
• Occur at both young and later age - double peak.
• More common in people from high SES areas.
• Enlarged, tender lymph nodes.
• Cyclic Pel-Ebstein fever (2-3 days) in 30% of cases - can produce a typical malaria-type fever.
• Produces weight loss, sweating, weakness, anorexia.
• Contiguous spread - staging important*
- Characterised by contiguous spread - doesn’t spread to distal organs immediately - arise in a single node and spread to anatomically contiguous lymphoid tissue.
• Staging very important for treatment/prognosis of HL:
- Stage 1 - single or one region lymph node.
- Stage 2 - more them one group above diaphragm.
- Stage 3 - below the diaphragm.
- Stage 4 - involvement of liver, spleen or bone marrow - high grade.
• Curable in most cases with radiation therapy and chemotherapy.

• A - absence of symptoms.
• B - fever, night sweats, weight loss (very common in HL compared to NHL).

Question 38

Describe the pathogenesis of Hodgkin’s lymphoma.

Answer 38

• Only Reed Sternberg cells are malignant. All other cells are reactive inflammatory cells - lymphocytes, neutrophils, macrophages and eosinophils* (not malignant).
• The more RS cells, the more malignant it is (high grade). Less RS cells - more inflammation (low grade).
• Malignant cells produce a lot of chemical mediators that bring in inflammatory response (element of inflammation in this type of cancer) - lymphoid malignancies with inflammatory response.
• Progresses by continuity nearby LN first. No metastasis* unlike NHL.
• Mediastinal lymphadenopathy is very typical (common). Starts in cervical region and spreads gradually. Patients present with lymphoid enlargement in the mediastinum suppressing trachea producing cough.
• Alcohol induced pain* - whenever patient drinks alcohol, HL lymph nodes become painful - characteristic but rare.
• Inflammatory response* and fibrosis* - inflammatory response with the malignancy and fibrosis is a special feature of HL.

Question 39

What are the 5 types of Hodgkin’s lymphoma?

Answer 39

1. Nodular sclerosis - most common, significant fibrosis producing septa.
2. Mixed cellularity - increased inflammatory response.
3. Lymphocyte-rich - too many lymphocytes with few RS cells.
4. Lymphocyte depletion - too many RS cells with less inflammatory cells.
5. Nodular lymphocyte predominance* - no EBV relation or mutation of Ig transcription factors. Male, popcorn cells.

• First 4 types known as classical HL - EBV and Ig transcription factors mutation.

Question 40

Describe the morphology of Hodgkin’s lymphoma.

Answer 40

Nodular sclerosis:
• Nodular, fibrous septa - diffuse lymphoid nodular mass separated by fibrous septa.
• Reed Sternberg cells - malignant B cells (all other cells are non-malignant).
- Large irregular binucleate malignant cells (large prominent double nuclei).
- Abundant cytoplasm.
- Presence of these cells is diagnostic of HL.
• Reactive inflammatory cells - eosinophils (eosinophilia)*, lymphocytes, neutrophils and plasma cells etc.
• More RS cell = poor prognosis.

*Difference to NHL:
• RS cells present in the case of HL (none in NHL).
• In NHL, all the cells look alike (uniform) because there are no reactive inflammatory cells - all the cells are malignant cells which are reasonably uniform.
• HL is mixed population of different types of cells - ready to differentiate (mixture of inflammatory cells with RS cells).

Question 41

Identify the variants of Reed Sternberg cells.

Answer 41

1. Classic binucleate form.
2. Can be single nucleus.
3. Can be popcorn cells - extensive clear cytoplasm - typical in nodular lymphocyte predominant HL - not related to EBV infections.
4. Can be multi-nucleated.

Question 42

Outline Non-Hodgkin’s lymphoma.

Answer 42

• Large group of lymphatic neoplasms.
• Clinical - fever, anaemia, infections, lymphadenopathy,. Splenomegaly +/-
• No RS cells or eosinophilia, random spread (stage?) - can spread from one place to a distance place without inbetween involvement unlike HL.

• Complex names and classification:
- Cell type - B, T and histiolytic (B commonest) - all HL are B cells. NHL - commonest is B but there are other cells also.

• Clinical - low, intermediate and high grade.
• Histology - see either small, large or mixed cells forming either follicles or diffuse. Malignancy of lymphocytes without other cells.
• Small lymphocytic lymphoma (SLL) - low grade (CLL*) - known as SLL or CLL - small cells usually associated with good prognosis - low grade lymphoma.
• Large lymphocytic lymphoma (LLL) - high grade (ALL*) - when cells large - LLL AKA high grade ALL. Larger the cell → worse the grade.
• Special types - Burkitt’s, Myeloma, Waldenstroms, lennert’s etc. - large group of many different types of lymphoma - remember the common ones.

Question 43

Differentiate between diffuse and follicular NHL.

Answer 43

• Uniform type of small cells (low grade) or mixture of small and large cells (intermediate) or only large cells (high grade).
• Diffuse - whole uniform sheaths of lymphocytes.
• Follicular - lymphoid follicles of normal lymph nodes.
• When follicles present - well differentiated - low grade.
• When diffuse - slightly high grade (if the cells are small - low grade). Cells large - high grade. Mixture - intermediate.

• BCL2 positivity - common stain used to confirm B lymphocytes. Immunophenotyping - positive in the follicles. Follicular lymphoma with BCL2 positivity - commonest type.

Question 44

Outline Burkitt’s lymphoma: B cell.

Answer 44

• Children/young - special type of B cell lymphoma occurring in young children (younger age).
• Type of large B cell lymphoma (high grade).
• Endemic in Africa (sporadic elsewhere).
• MYC-IgH translocation on 14-EBV* - characteristic MYC gene with IgH translocation on chromosome 14 - related to EBV infection.
• Larger dark blast cells, lipid vacuoles, plenty of scattered macrophages (starry sky)* - dark cells with bright macrophages inbetween - starry sky pattern typical of Burkitt’s lymphoma.
• Surface B cell marker and IgM.
• Typically presents in the facial maxillary region. Large tumours, high grade lymphomas.
• Microscopy shows lipid vacuoles, similar to ALL L3 type.

Question 45

Outline MGUS.

Answer 45

• Monoclonal Gammopathy of Undetermined Significance.
• Most common - type of plasma cell neoplasm. Plasma cells are the B lymphocytes producing immunoglobulins.
• Chronic plasma cell neoplasm - very slow growing (very benign).
• 1-3% of healthy adults >50y (seen in normal people without any symptoms after the age of 50 years - disease of later age group).
• <3 gm/dl monoclonal gammaglobulins - clinically diagnosed when serum monoclonal gammaglobulins <3g (> 3g is known as myeloma).
• Develop myeloma (malignancy of plasma cells), plasmacytic lymphoma, amyloidosis (due to production of too much immunoglobulins) etc. 1%/year.
• Normal long-lived plasma cell becoming neoplastic.
• When it is very little → known as MGUS - neoplastic plasma cells but not producing too many antibodies (<3g) → gradually can become more and more severe to become an acute leukaemia like picture of myeloma.

Question 46

Differentiate between Hodgkin’s lymphoma and Non-Hodgkin’s lymphoma.

Answer 46

Hodgkin’s Lymphoma:
• Age - average age 28y with 2 peaks - 25y and 65y.
• Occurrence - <10% of all lymphomas.
• Location and spread - cervical, chest and mediastinal 85%, extranodal in 4% Contiguous spread. Mesenteric & Waldeyer ring involvement - uncommon.
• Affected cells - B lymphocytes with RS cells.
• Symptoms - more likely to have systemic B symptoms.
• Progression - early diagnosis, predictable, better prognosis.

Non-Hodgkin’s lymphoma:
• Age - average age is about 67y.
• Occurrence - >60% of all lymphomas.
• Location and spread - multiple sites. Chest in 40%, extra nodal in ~23% and BM non-contiguous spread. Mesenteric & Waldeyer ring (tonsilar ring) involvement common.
• Affected cells - B, T, histiocytes, NK cells depending on the subtype. No RS cells.
• Symptoms - less likely to have B symptoms (27%).
• Progression - less predictable, early spread, good to worse prognosis.

Question 47

Differentiate between myeloproliferative disorders and myelodysplastic syndromes.

Answer 47

• Myeloproliferative Disorders (MPD) - stem cell neoplasm with maturation - increased cells.
- Excess proliferation with maturation results in increased peripheral cells.

• Myelodysplastic Syndromes (MDS) - stem cell neoplasm - dysplastic - destruction - decreased cells.
- Same stem cell neoplasm but they are so abnormal they get destroyed in the marrow resulting in peripheral pancytopenia - decreased cells.

Question 48

Outline myeloproliferative disorders.

Answer 48

• Neoplastic stem cell proliferation, slow, chronic - slow growing cancer, chronic, goes on for years, mature to normal looking but cancerous cells.
• Increased tyrosine kinase activity due to JAK2 activation on 9p*, PDGF mutations → growth factor hypersensitivity (BCR-ABL in CML).
• Due to increased tyrosine kinase activity. Commonest mutation seen is JAK2 activation on the short arm of chromosome 9. Usually associated with growth factor hypersensitivity.
• JAK2 commonest in all MPD expect CML - different mutation → BCR-ABL (also results in malignancy but different mutation).

• Slow proliferation with maturation resulting in increased number (abnormal) of cells, also hepatosplenomegaly (due to spreading).

Question 49

Describe the classification of myeloproliferative disorders.

Answer 49

1. Polycythemia vera (PV) - RBC - maturation towards RBC.
2. Chronic myeloid leukaemia (CML) - WBC - maturation towards WBC.
3. Essential thrombocythemia (ET) - Platelet - maturation into platelets (all the malignant cells becoming platelets).
4. Myelofibrosis (MF) - fibroblasts*
   - Proliferation of fibroblasts but it is not primary MPD - it is secondary to other 3 conditions.

• Mixed - common - although described as separate entities (i.e. polycythemia, CML etc.) → many times along with RBC proliferation, there will be proliferation of other cells as well (mixture) e.g. polycythemia - RBCs markedly increased but can also be increased WBCs and platelets as well.

• Transform to acute leukaemia (AML)/myelofibrosis after years. All of these are neoplasms of stem cells - just like leukaemia, they can transform to acute leukaemia (after man years) or the whole marrow undergoes myelofibrosis (scarring of marrow after many years).
• Outcome of these disorders is either leukaemia or myelofibrosis (if patient does not die of their disease).

Question 50

Outline polycythemia rubra vera.

Answer 50

• Excess proliferation of all cells. Increased RBC mass.
- Disease due to marked proliferation in the marrow of erythroid cells - hypercellular marrow - too many RBCs.
- Increased RBC and increased HCT. Also associated with increased WBC, increased platelets (MPD - excess proliferation of all cells, dominantly effecting RBC).
• Activation of JAK2 - in all cases. JAK2 (common in all MPD) → tyrosine kinase activator → makes the neoplastic cells growth factor independent proliferation - do not require EPO - start continuously dividing and producing RBC.
• Neoplastic - growth factor independent proliferation.
• Low serum erythropoietin - serum EPO decreased as there is increased RBC (suppressed).
• High viscosity, vascular stasis, infarctions.
- Neoplastic erythrocytes → plenty of RBCs → blood becomes thick (too many RBCs) - vascular stasis and infarction.
- Blocking/rupture of capillaries also common.
• Bleeding - BV damage, platelet abnormality.
• Hypercellular bone marrow - plenty of erythroid cells.
• May progress to myelofibrosis after many years. Rarely to AML.

Question 51

Outline essential thrombocythemia

Answer 51

• JAK2 tyrosine kinase activation.
• Increased platelets, megakaryocytes.
- Same mutation is effecting megakaryocytes →
increased production of platelets (cancerous
stem cells are producing uncontrolled continuous
proliferation of abnormal platelets - do not
function (haemostasis) → cause bleeding.
• Large and abnormal platelets → bleeding (patients present with marked bleeding).
• Primary myelofibrosis common - PDGF.
- Increased platelets produce PDGF
(platelet derived growth factor) -
stimulates fibroblasts (same as
wound healing) → results in
scarring of the marrow.
• Hepatosplenomegaly (neoplastic stem cells infiltrate into the liver, spleen and lymph nodes).
• Transformation to AML - late and rare (may progress to AML at later stage).

• Clinically see plenty of platelets (high platelet counts), even megakaryocytes come out into the peripheral blood (normally should only be in the marrow). The platelets are very large - all products of malignant megakaryocytes.

Question 52

Outline primary myelofibrosis.

Answer 52

• Late age, chronic slow progress (slow progression of scarring of the marrow).
• End result of PV, ET and other MPDs.
- Not a primary disease itself. Can also be a primary myelofibrosis when the other components are not prominent.
- When the patient presents clinically - they would have already undergone total fibrosis.
• JAK2 tyrosine kinase activation.
• Increased marrow fibrosis due to PDGF and TGFβ from neoplastic stem cells and megakaryocytes (fibroblasts are non-neoplastic).
- Fibrosis is not part of the malignant process (not neoplastic) - it is a reaction to the growth factors produced by malignant cells. The whole marrow is fibrosing/scarring.
• Massive hepatosplenomegaly - due to extramedullary haemopoiesis.
• Produced abnormal RBC - anaemia (abnormal RBCs that break down producing anaemia).
• Many teardrop RBC* - very typical of myelofibrosis.
• Infections/bleeding - terminal.
• Transformation to AML - rare.

Question 53

Describe the pathogenesis of myeloproliferative disorders.

Answer 53

• MPD - bone marrow stem cell neoplasia can affect:
- Granulocyte precursors (WBC).
- RBC.
- Megakaryocytes.
• 3 major types giving rise to either CML, polycythemia or essential thrombocytopenia (3 conditions of malignant proliferations of a slow progression, chronic condition).
• These conditions can give rise to either (end result): AML or myelofibrosis through the production of chemical mediators of fibrosis.
• Reactive fibrosis - reactive condition.

Question 54

Outline myelodysplastic syndromes.

Answer 54

• AKA refractory Anaemia/Pre-leukaemia.
• Increasingly common, more then 80% of cases present after the age of 60 yo.
• Clonal proliferation of transformed stem cell - deletions of 5q - common.
- Different mutation - 5q deletion - long arm of chromosome 5 deletion - results in excess proliferation of totally abnormal (both structurally and functionally) dysplastic cells - abnormal dysplastic cells - do not come out in the peripheral blood - results in peripheral pancytopenia (decreased RBC, WBC and platelets).
- Difference to MPD which are functionally abnormal but structurally mature cells - normal looking.
- Difference - in the marrow wall, there will be too many cells which is the same as MPD but these cells are very abnormal. Peripheral blood shows very few abnormal cells, irregular (predominantly RBCs, few WBCs).
• Excess proliferation of functional and structurally abnormal dysplastic cells.
• Majority are destroyed in marrow → ineffective myelopoeisis → peripheral pancytopenia.
• Present with anaemia, infections and bleeding (similar to leukaemia).
• Chronic slow progression, one or more cell lines involved. RBC*
- Chronic, slow progression effecting either one or more cells lines → commonest is RBC involvement - anaemia most common in these patients.
• Later transforms to AML in 10-40% cases (little more then MPD).

Question 55

Outline FAB classification for refractory anaemia.

Answer 55

1. RA: Refractory Anaemia (BM Blasts <1%) - effects only RBCs mildly - bone marrow blast count <1%.
2. RARS: RA with ring sideroblasts (<1%) - little more abnormal RBCs with iron deposits around the nucleus of erythroblasts (known as sideroblasts).
3. RAEB: RA with excess blasts (<5%) - advanced stage with excess blasts in the marrow - means the disease is a bit more faster developing (rapidly progressive, high grade).
4. RAEB-T: RAEB in transformation (5-30%) - same RA with excess blasts in transformation - when the blast counts >5% (up to 30%).
   • >30% blasts in BM → Leukaemia.