HIS21 HIS22 White Cell Disorders And Their Investigation I + II Flashcards
White cell disorders framework
- Reactive
- response of haemopoietic system to other abnormalities
- mainly Quantitative changes in normal white cell types (most common explanation for quantitative white cells disorders)
- Qualitative changes possible e.g. atypical lymphocytosis, appearance of immature cells in PB - Malignant
- primary abnormality of haemopoietic system
- both Quantitative + Qualitative changes - Functional
- primary abnormality of haemopoietic system
- rare in practice
***White cell disorders investigations
記: CMCICM —> 3C, 2M, 1I (CBC, Cytochemistry, Cytogenetics, Morphology, Molecular genetics, Immunophenotype)
- CBC
- WBC
- Differential count (Machine vs Manual count)
- Machine: cannot distinguish abnormal cell types (e.g. blasts) —> need manual - Morphology
- PB smear
- BM aspiration
- Trephine biopsy (BM examination) - Cytochemistry
- Myeloid lineage —> Myeloperoxidase, Sudan Black B
- Lymphoid lineage —> Immunophenotyping - Immunophenotype
- Flow cytometry
- Immunohistochemistry - Cytogenetics
- Karyotyping —> for PB/BM aspiration
- Fluorescence in-situ hybridisation —> for Trephine biopsy - Molecular genetics
- PCR
Other investigations:
- CXR
- LN biopsy
- Inflammatory / Autoimmune markers
- Tumour markers
- Fe profile
- PT/APTT + Platelet count for bleeding tendency
- Drug history
Morphology
- PB smear:
- confirm nature of cytopenia / increased WBC count
- detect abnormal cell types / abnormal morphology - BM aspirate (i.e. BM blood):
- determine **cellularity
- detect abnormal cell types / dysplastic morphology
- ascertain activities of trilineage **haemopoiesis - Trephine biopsy:
- preserved BM architecture i.e. aspirate
—> **Bone structure
—> **Marrow cellularity
—> **Pattern of involvement by abnormal cells
—> Marrow fibrosis
- permit immunophenotyping by immunohistochemistry
- **less sensitive than aspirate for assessing cytological detail (e.g. dysplastic features)
Cytochemistry
- performed on PB / BM aspirate
- detect Dye / Reaction product in cells-of-interest using microscopy
- Myeloid lineage cytochemical markers: Myeloperoxidase / Sudan Black B (show that cells have commit to Myeloid lineage)
- Lymphoid lineage: Immunophenotyping
Immunophenotyping
- Determine cell lineage
- by detecting antigens on cells-of-interest
Myeloid lineage:
- Myeloperoxidase
- CD117, CD13, CD33 (x rmb)
Lymphoid lineage:
- B-Acute Lymphoblastic Leukaemia: CD19, CD79a, CD22
- T-Acute Lymphoblastic Leukaemia: CD3
2 ways:
- Flow cytometry (only for **liquid)
- performed on **PB / BM aspirate
- investigate co-expression of antigens on a cell
- use Anti-Ag Ab with ***fluorochromes —> wash away unbound Ab —> shine light on fluorochrome —> read colour signal —> know which Ag on cell —> know which cell - Immunohistochemistry
- performed on **Trephine biopsy
- difficult to demonstrate co-expression of antigens on single cell
- use Anti-Ag Ab with **dyes —> read positive cells on biopsy specimen
- also see ***spatial relationships between cells (e.g. clustering)
Cytogenetics
Many haematological malignancies harbour certain characteristic chromosomal abnormalities
Use: Diagnosis, ***Prognostication, Selection of treatment
- Karyotyping
- study of chromosomes at Metaphase (when chromatin highly condensed and chromosome morphology is well-defined) - Fluorescence in-situ hybridisation (FISH)
- Single-stranded DNA probes (labelled by Fluorophores to allow detection by fluorescence microscopy) + Complementary DNA sequences on subject
—> form hybrid double-stranded complexes
—> wash away unbound probe
—> shine light on fluorochrome
—> read colour signal
—> know which **DNA sequence present / determine ↑/↓ in copy of number of genes / whether there is **fusion of genes
Molecular genetics
- Determine ***sequence changes in DNA/RNA (different diseases have different characteristics of sequence changes)
- Detection of ***genetic mutations in specific genes
- Usually ***PCR-based
- Multiple types of end-point detection, tailored for the expected sequence changes to be observed
—> Point mutation
—> Insertion / Deletion
—> Fusions
Use: Diagnosis, ***Prognostication, Selection of treatment
Framework of clinical approach
“Handle” —> Causes —> “Further Interrogate” —> Diagnosis
- Understand clinical problems
- History taking (symptoms)
- Physical examination (signs)
- Investigations
—> decide on “diagnostic handle” - Consider causes of the “diagnostic handle”
- require prior knowledge
- generate differential diagnoses
- prioritise according to likelihood - Goal-directed history taking, physical examination, investigations to rule in / out causes
- require prior knowledge - Arrive at final diagnosis
- Direct history taking, physical examination / investigations to guide further management
- look for complications
- prognosis
- treatment - Treat the condition
Case 1a:
- 63 yo male
- ex-smoker
- not on medication
- cough and blood-stained sputum for 2 weeks
- no lymphadenopathy
- no cyanosis
- hyperinflated chest
- reduced breath sounds
- no adventitious sounds
- abnormal blood count
Total WBC: ↑↑ RBC: ↓ Platelet: Normal Neutrophil: ↑↑ Monocyte: ↑ Eosinophil: ↑↑ Basophil: ↑ Lymphocyte: Normal
Steps:
1. History taking
- Physical examination
- Infection: cough, blood-stained sputum, but no fever
- Inflammation: none
- Solid tumours / haemic malignancies: blood-stained sputum, favouring factors: ex-smoker, obstructive lung disease (∵ hyperinflated chest)
- Drug history: none - Investigations (for Infection / Malignancies)
- CBC: Leukocytosis (**Neutrophilia, Monocytosis, **Eosinophilia, Basophilia)
- PB smear
- Microbiological investigations: -ve sputum culture, Acid-Fast Bacilli (AFB) smear and culture
- Imaging: CXR -ve, CT thorax with contrast: 5cm spiculated mass in left lower lobe of lung —> Lung biopsy: Adenocarcinoma
- Tumour markers
- Marrow exam if indicated - Conclusion
- Lung adenocarcinoma
Haematological diagnosis:
-
Myeloid leukaemoid (look like leukaemia) reaction secondary to lung adenocarcinoma (*reactive response to non-haematological abnormality)
1. Eosinophilia, Monocytosis —> part of leukaemoid reaction
2. Anaemia —> secondary to anaemia of chronic disease (less likely BM infiltration by metastasis)
3. Neutrophilia —> can be multiple causes (e.g. pneumonia due to airway obstruction by lung adenocarcinoma)
***Clinical approach to Leukocytosis
- Confirm Leukocytosis
- spurious causes possible e.g. circulating nucleated RBC mistaken - Ascertain which WBC subtype that ↑
- machine count not reliable in other cell types other then neutrophils, lymphocytes, monocytes, eosinophils, (basophil: not very accurate either) - When in doubt always request manual PB smear review
***Clinical approach to Neutrophilia
Causes:
1. Infections
- ***Bacterial (esp. pyogenic)
—> check for signs/symptoms of infection (fever, cough, sputum, diarrhoea, dysuria)
—> further microbiological investigations directed against suspected infections
- Inflammation
—> check for signs/symptoms of inflammation (skin rash, photosensitivity, joint pain)
—> further investigations for inflammatory markers (ESR, CRP), autoimmune markers - Malignancy
- Solid tumours
—> S/S + Imaging
- Haematological
—> ***Myeloproliferative neoplasms (esp. Chronic myeloid leukaemia, Myelofibrosis)
—> S/S
—> PB smear +/- BM exam, tumour markers - Drugs
- Steroids (demargination of neutrophils on blood vessels)
- Growth factors
—> check for drug history
Case 1b:
- history of renal cell carcinoma with nephrectomy done
- malaise, early satiety
- splenomegaly down to umbilicus
“Handle”:
- Splenomegaly: find out causes
“Further interrogation”:
- CBC, PB smear:
- ↑ WBC (Marked Leukocytosis) —> Bimodal distribution of Myelocytes + Neutrophils
- ↑↑ Neutrophil, Myelocytes
- ↑↑ Basophils (***Basophilia)
- Thrombocytosis
- BM: ↑ Granulopoiesis, ↑ Myeloid cells, Megakaryocytes (with abnormal pathology) - Cytogenetics:
- translocation **(chromosome 9;22) in over 95%
- other variant subtypes may require FISH to confirm —> **BCR-ABL1 fusion (normally BCR, ABL signals are separate ∵ genes located on separate chromosomes) - Molecular genetics:
- PCR: all harbour BCR-ABL1 fusion (Philadelphia chromosome) by definition
Diagnosis:
- Neutrophilia + Splenomegaly
—> Myeloproliferative neoplasms
—> ***Chronic myeloid leukaemia
Treatment:
Targeted therapy:
- ***Tyrosine kinase inhibitors (now standard treatment for CML)
—> Molecular monitoring of disease level (standard practice in CML)
***Causes of Splenomegaly
4 Categories: Increased function, Immune hyperplasia, Abnormal blood flow, Infiltration
- Haematological
- **Malignancy: **Myeloproliferative neoplasms (massive in CML, MF), Leukaemia, Lymphoma
- **Removal of defective RBC: Thalassaemia intermedia / major
- **Immune hyperplasia: Haemolytic anaemia (AIHA) - Portal hypertension
- Some infections
- infectious mononucleosis
- infective endocarditis
- malaria
- schistosomiasis
- leishmaniasis - Autoimmune diseases
- Storage diseases (in paediatrics)
***Clinical approach to Thrombocytosis
- Reactive
- ***Bleeding, Fe deficiency —> check Fe profile
- Inflammation, Autoimmune disease —> check inflammatory markers - Malignant
- ***Myeloproliferative neoplasms —> check PB smear, marrow exam, molecular genetics
- Solid tumours - ***Hyposplenism
- most commonly post-splenectomy
Case 2:
- 57 yo female
- Type 1 DM
- on insulin
- epigastric discomfort
- mild epigastric tenderness
- no hepatosplenomegaly
- no lymphadenopathy
- noted deranged liver function
CBC:
- Leukocytosis
- Eosinophilia
- Megakaryocytic hyperplasia
Eosinophilia: History / Physical examination:
- Drug history —> OTC health supplement 1 month
- Allergic symptoms / history —> None
- Autoimmune features (e.g. skin rash, joint pain) —> None
- Travel history (parasitic infestations) —> None
- Lymphadenopathy —> None
Further investigations:
1. PB smear: look for features of MPN, blasts, abnormal lymphoid cells
—> Eosinophilia
- Autoimmune markers
—> -ve - Microbiological screening: Stool culture, Ova / cysts (for parasites)
—> -ve - CXR (for solid tumours / lymphoma): Lung, mediastinal mass
—> Normal CXR - BM examination (if suspected haematological malignancies): may need cytogenetics / molecular testing
—> Granulocytic + Megakaryocytic hyperplasia, with Eosinophilia
—> No evidence of haematological malignancies
—> Cytogenetics: 46, XX (normal) - LN biopsy (if suspected lymphadenopathy/lymphoma)
—> No lymphadenopathy
Diagnosis:
- Eosinophilia reactive to OTC medication (most likely, not definitive)
Progress:
- Eosinophilia subsiding after cessation after medication
- liver function normalised gradually (deranged liver function probably drug-related)
***Clinical approach to Eosinophilia
Eosinophilia: PB smear: look for features of MPN, blasts, abnormal lymphoid cells
- Drug reactions —> Drug history
- Allergic conditions —> Allergic symptoms / history
- Autoimmune diseases —> Autoimmune features (e.g. skin rash, joint pain), Autoimmune markers
- Infections esp. parasitic infestations
—> Travel history (parasitic infestations)
—> Microbiological screening: Stool culture, Ova / cysts (for parasites) - Malignancies
- Lymphomas (T cell lymphoma, Hodgkin lymphoma) —> LN biopsy
- Myeloproliferative neoplasms
- Solid malignancies (Leukaemoid reactions)
—> Lymphadenopathy: **LN biopsy
—> **CXR (for solid tumours / lymphoma): Lung, mediastinal mass
—> ***BM examination (if suspected haematological malignancies): may need cytogenetics / molecular testing
Case 3a:
- 44 yo male
- good past health
- gum bleeding for 3 days after tooth extraction
- fever
- no petechiae
- no retinal haemorrhage
- unremarkable physical exam otherwise
CBC:
- Pancytopenia (WBC, RBC, PLT) esp. ***Thrombocytopenia
- Blast in PB
- Abnormal promyelocytes with Auer rods (Faggot cell)
PT/APTT:
- normal
- normal fibrinogen
- D-dimer slightly ↑
Diagnosis:
- Acute Promyelocytic leukaemia (APL) (synonym: APML, M3)
Diagnostic evaluation of Acute leukaemia:
- Morphology, including cytochemistry
- Abnormal promyelocytes with Auer rods (Faggot cell)
- Strongly +ve for Myeloperoxidase and Sudan Black B - Immunophenotyping
- Cytogenetics and molecular genetics
- t(15;17)
Treatment:
- Chemotherapy
- **All-trans retinoic acid (ATRA) —> allow promyelocytes to **differentiate
- **Arsenic trioxide
—> ATRA, Arsenic trioxide targets PML-RARa protein
—> **PML-RARa protein degradation
Clinical approach to Bleeding tendencies
- Bleeding symptoms
- Prior history of bleeding challenges
- Family history
1st line investigation:
- CBC (***platelet count)
- ***PT/APTT
***Clinical approach to Pancytopenia
Marrow causes (Production causes):
- Megaloblastic anaemia —> diet history, CBC, PB smear, folate/B12 levels
- Aplastic anaemia —> BM exam
- Myelodysplastic syndrome (MDS) —> BM exam
- Marrow infiltration —> BM exam
- Leukaemia —> BM exam
- Inherited (rare) —> clinical features, special test, usually require genetic testing
Peripheral / non-marrow causes (Consumptive causes):
- Infections —> symptomatology, microbiological workup
- Autoimmune —> symptomatology, autoimmune markers
- Drug-induced —> drug history
- Splenomegaly (pooling effect) —> physical examination, imaging
***Cytopenia
Common manifestation of haematological malignancies
- Leukopenia / Leukocytosis (depends balance between Normal cell ↓/ Abnormal cell ↑)
- **Anaemia, **Thrombocytopenia usually
- ***Neutropenia (Neutrophil will ↓ regardless)
WBC count may ↑/↓ in haematological malignancies:
- Normal count ↓ (e.g. neutropenia)
- Abnormal cells ↑
***Diagnostic evaluation of Acute Leukaemia
- Morphology, including Cytochemistry —> determine cell lineage
- >=20% blasts in PB / BM
- Myeloid (AML) / Lymphoid (ALL)
- Morphology alone: difficult to distinguish myeloblasts from lymphoblasts
—> ***Auer rod: Pathognomonic feature of Myeloid neoplasms (e.g. AML, MDS)
—> AML: further sub-classification based on morphology - Immunophenotyping
- Cytogenetics and molecular genetics
***Diagnosis of Acute Promyelocytic leukaemia
APL a subtype of AML, though now treated as a distinct entity due to clinical emergency
- Clinical features:
- Anaemic symptoms
- Bleeding tendencies - Blood count:
- ***Pancytopenia (classical) - Clotting profile:
- ***Disseminated intravascular coagulation (DIC) (characteristic!!!) —> D-dimer ↑ - Morphology:
- ***Faggot cells (characteristic) - Cytochemistry:
- Strongly positive for Myeloperoxidase and Sudan Black B (show that cells committed to Myeloid lineage) - Cytogenetics:
- ***t(15;17) (由17 translocate去15) - Molecular genetics:
- Fusion gene of ***PML-RARa detected by PCR / FISH
APL: medical emergency
- Fatal intracranial bleeding secondary to **thrombocytopenia and **DIC
- On-call pathology service in place
- Urgent treatment with ***all-trans retinoic acid (ATRA)
—> induce cells to differentiate to lessen damaging effects - May need ***supportive infusion esp. platelets, plasma (to prevent DIC)
Case 3b:
- 51 yo male
- history of nasopharyngeal carcinoma
- anaemic symptoms: SOB, pale
- no bleeding symptoms
CBC:
- ***Pancytopenia (low WBC, neutrophil, RBC, platelet)
- Neutropenia
- Few blasts in PB
PB smear:
- Neutrophil hypolobated, lacks granules in cytoplasm (hypogranularity)
—> Dysplastic Neutrophils
BM exam:
- ***Hypercellular
- ***Focal prominence of blasts (<20%)
- Increased + ***Dysplastic erythroid precursors and megakaryocytes
Conclusion:
- Myelodysplastic syndrome (secondary to previous chemotherapy)
Cytogenetics:
- complex karyotype including del(5q) + monosomy 7
—> poor prognosis (require more aggressive treatment)
***Clinical approach to Neutropenia
- Infection —> symptomatology, microbiological workup
- ***Viral (e.g. CMV, HIV, EBV, hepatitis, parvovirus) - Autoimmune —> symptomatology, autoimmune markers
- Drug-induced —> drug history
- Marrow causes —> BM exam
- Marrow infiltration
- Leukaemia
- Aplastic anaemia
- Myelodysplastic syndrome (MDS) - Inherited (very rare) —> clinical features, special test, usually require genetic testing
***Myelodysplastic syndrome
Features:
- Cytopenia(s) in PB
- Hyperplastic marrow
- Dysplastic features in Myeloid, Erythroid, and/or Megakaryocytic lineage(s)
***Diagnostic evaluation of MDS
- CBC
- ***Cytopenia
- Red cell macrocytosis - Morphology of PB and BM
- **Cellularity of marrow
- Blast percentage
- **Dysplastic features in Myeloid, Erythroid, and/or Megakaryocytic lineage(s) - Cytogenetics
- Determine prognosis
Case 4a:
- 2 yo boy
- good past health
- fever 1 month
- unremarkable physical examination
CBC:
- Leukocytosis
- Lymphocytosis
- ***Blasts in PB
- Mild anaemia
- Thrombocytopenia
Suggestion:
- Acute leukaemia
Further investigation:
- BM exam
- Cytochemistry —> -ve for Myeloperoxidase and Sudan Black B —> Lymphoid lineage
- Immunophenotyping (Flow cytometry) for lymphoid lineage
—> -ve CD3 (T cell marker), +ve CD19 (B cell marker), -ve MPO (myeloid marker), +ve CD79a (B cell marker)
—> B cell lineage
Diagnosis:
- B Acute lymphoblastic leukaemia (BALL)
Cytogenetics to Determine prognosis
- Hyperdiploid karyotype (>46 chromosomes) (characteristic of B-ALL)
—> favourable prognosis
***Clinical approach to Lymphocytosis
- ***Reactive
- Lymphocytosis: Infections, Autoimmune disease
- Atypical lymphocytosis: Viral infections, Autoimmune disease
—> Symptomatology, Microbiological workup, Autoimmune markers - ***Malignant (Haematological malignancies)
- Acute: ALL
- Chronic: CLL, Other Leukaemic phase of lymphomas
—> CBC, PB smear, Cytochemistry, Immunophenotyping (Flow cytometry)
(1. Morphology, including cytochemistry —> determine cell lineage
- >=20% blasts in PB / BM
- Myeloid (AML) / Lymphoid (ALL)
- Morphology alone: difficult to distinguish myeloblasts from lymphoblasts
—> ***Auer rod: Pathognomonic feature of Myeloid neoplasms (e.g. AML, MDS)
—> AML: further sub-classification based on morphology
2. Immunophenotyping
3. Cytogenetics and molecular genetics)
Atypical (Reactive) Lymphocytosis
Lymphocytosis with increased atypical lymphocytes
Causes:
- Prototype: ***Infectious mononucleosis
- but many viral infections can give rise to Atypical Lymphocytosis as well
- autoimmune disease possible
NOT to be mistaken as blasts / lymphoma cells when reading report
Case 4b:
- 63 yo female
- good past health
- bilateral neck lumps
- no fever, weight loss, night sweats
- no other symptoms
- multiple bilateral cervical lymphadenopathy
- no hepatosplenomegaly
CBC:
- Lymphocytosis
- Abnormal lymphoid cells
Immunophenotyping:
- Typical CLL immunophenotype by flow cytometry
Diagnosis:
- CLL
***Clinical approach to Lymphadenopathy
- ***Infection
- Pyogenic
- Viral
- TB
—> symptomatology, CBC, microbiological workup, CXR - ***Autoimmune diseases / Inflammatory diseases
—> symptomatology, CBC, autoimmune markers - Malignancies
- Haematological: **Lymphoma (most common), Leukaemia (possible)
- **Solid tumour: Carcinoma (with metastasis to LN)
—> symptomatology, CBC, PB smear, imaging, LN biopsy
***Diagnostic evaluation of CLL/Lymphoma
- Morphology
- PB smear
- BM exam
- LN biopsy - Immunophenotyping
- Diagnostic classification —> Lymphoid / Myeloid lineage - Cytogenetics / FISH
- Prognosis determination
***Causes of Monocytosis
- Infections
- esp. ***TB
- bacterial infections - Autoimmune diseases
- ***Chronic myelomonocytic leukaemia (CMML)
- MDS/MPN neoplasm (a bit of both)
***Causes of Basophilia
Uncommon in clinical setting
-
**Myeloproliferative neoplasms (most probably)
- esp. **CML - Autoimmune diseases (uncommon)
- Allergic conditions (uncommon)
CLL, CML, Myeloproliferative neoplasms, Plasma cell myeloma
CLL:
- B lymphocyte acquired mutation —> proliferate (more downstream, ∴ no blasts)
CML:
- HSC acquired mutation —> proliferate and differentiate more to Myeloid lineage (more up stream, ∴ can still see blasts although small no. compared to Acute leukaemia)
Myeloproliferative neoplasms:
- Chronic myeloid leukaemia
- Essential thrombocytopenia (ET) —> Megakaryocytes
- Polycythemia Vera (PV) —> RBC
- Primary myelofibrosis (PMF)
—> Common myeloid progenitor acquired mutation
—> uncontrolled proliferation + retain ability of differentiation
Plasma cell / Multiple myeloma:
- Plasma cell accumulation
Myeloproliferative neoplasm
Philadelphia chromosome +ve:
- Chronic myeloid leukaemia
Philadelphia chromosome -ve:
- Essential thrombocythemia
- Polycythaemia Vera
- Myelofibrosis
Acute vs Chronic leukaemia
Distinguished by disease tempo
Acute: Rapid progression and fatal if not treated
- Usually caused by Immature cell types (AML, ALL)
- Blasts >=20% in PB/BM
Chronic: Slower progression
- Usually caused by Mature cell types (Mature B cell lymphoma, Mature T cell lymphoma, NK cell lymphoma, Hodgkin lymphoma)
- some mature entities progress rapidly e.g. Burkitt lymphoma, diffuse large B cell lymphoma etc.
Immature vs Mature
Distinguished by maturation stage of malignant cells (by Morphology, Immunophenotype)
Immature:
- Acute myeloid leukaemia
- B lymphoblastic leukaemia/lymphoma
- T lymphoblastic leukaemia/lymphoma
Mature:
- B cell lymphoma
- T cell lymphoma
- NK cell lymphoma
- Hodgkin lymphomas
Leukaemia vs Lymphoma
Leukaemia: disease primary involves/originate from ***BM / blood
(AML, APL, ALL, CML, CLL)
Lymphoma: disease primary involves/originate from LN, spleen, lymphoid tissue, other tissues (e.g. nasopharynx, GI tract)
—> 2 conditions are NOT mutually exclusive
Examples:
Acute / Chronic myeloid leukaemia: almost entirely leukaemia
Acute lymphoblastic / Chronic lymphocytic leukaemia: depends on site of malignancy —> can be leukaemia / lymphoma
Follicular lymphoma: mainly in lymphoid tissue —> lymphoma —> but if severe enough to involve BM/blood —> Follicular lymphoma in leukaemic phase
Same principles apply to other lymphoma:
xxx lymphoma —> severe enough to involve BM/blood —> xxx lymphoma in leukaemic phase
MDS vs MPN vs MDS/MPN
Mutations for proliferation —> Uncontrolled proliferation
- more towards MPN
Mutations for differentiation —> Impaired differentiation
- more towards MDS
Mutations for both coexist
- MDS/MPN (some features of MPN while have dysplastic morphology)
- esp. CMML
—> Disease phenotype depends on pattern of mutations in a particular patient
—> Rmb NOT clear cut!!!
Miscellaneous concept: Massively Parallel Sequencing for DNA
Massively parallel sequencing performs millions of DNA sequencing in parallel (at the same time)
- Whole genome sequencing
- still not used in clinical setting - Whole exome sequencing
- ALL exons of protein-coding genes
- Diagnosis of rare inherited diseases - Targeted sequencing
- Selection of genes
- Increasingly common in cancer testing
Summary of White cell disorders
Reactive: MOST common in clinical practice
- infections, inflammation, non-haemic malignancy, drug
Intrinsic abnormalities
- Malignant white cell disorder: uncommon but important to recognise
- Inherited white cell disorder: rare
—> numerical vs functional
Diagnosis requires
- Ascertainment of abnormal cell type
- Pursue corresponding causes after taking into account all clinical features and investigational findings using the steps of clinical approach highlighted
- Recognise patterns for features of diseases
Summary of cases
Case 1a: Leukaemoid reaction
- Myeloid leukaemoid reaction secondary to lung adenocarcinoma —> reactive response to non-haematological abnormality
Case 1b: CML
- Clinical presentation
- morphology
- cytogenetics + FISH —> t(9;22) + BCR-ABL1 fusion
- molecular
Case 2: Eosinophilia secondary to drug reaction
Case 3a: APL
- morphology, cytochemistry, cytogenetics + FISH, molecular —> t(15;17), PML-RARa fusion
- medical emergency
- treatment
Case 3b: MDS
- morphology —> Pancytopenia, Neutropenia
- cytogenetics
Case 4a: B-ALL
- Leukocytosis, Lymphocytosis, Blasts in PB, Anaemia, Thrombocytopenia
- flow cytometry —> B cell markers: CD19 +ve, CD79a +ve
- cytogenetics + FISH —> Hyperdiploid karyotype (>46 chromosomes) (characteristic of B-ALL)
- molecular
Case 4b: CLL
- clinical
- morphology
- immunophenotype FISH
- concept of lymphoma in leukaemic phase
***Summary of clinical approaches
- Leukocytosis
Clonal
- Blasts >20% —> AML / ALL
- Blasts <20% —> Other myeloid malignancy (MDS, MPN, CMML)
- No leukaemic blasts but abnormal lymphoid cells present (e.g. B-CLL)
Reactive (“Leukaemoid”) —> ***BUT won’t be sky high (rarely >50) - search for underlying cause —> infection —> inflammatory / autoimmune —> paraneoplastic —> reactive to solid organ tumours
- Leukopenia
- Neutrophilia
- Solid tumours
- MPN (esp. CML, MF) - Eosinophilia
- Lymphoma (T cell lymphoma, Hodgkin lymphoma)
- MPN
- Solid tumour - Basophilia
- MPN (esp. CML) - ***Pancytopenia
- APL
- Megaloblastic anaemia
- Aplastic anaemia
- MDS
- Marrow infiltration - Neutropenia
- Aplastic anaemia
- MDS
- Marrow infiltration
- Leukaemia
- Viral infection - Lymphocytosis
- Acute: ALL
- Chronic: CLL, leukaemic phase of lymphoma —> Lymphadenopathy
- Reactive (Infectious mononucleosis) - Monocytosis
- CMML
- TB - Thrombocytosis
- Bleeding / Fe deficiency
- MPN (ET)
- Hyposplenism - Lymphadenopathy
- Infection
- Autoimmune
- Lymphoma
- Solid tumour - Splenomegaly
- Increased function: Thalassaemia intermedia / major
- Immune hyperplasia: Haemolytic anaemia (AIHA), Infectious mononucleosis
- Abnormal blood flow: Portal hypertension
- Infiltration: MPN, Leukaemia, Lymphoma
(Leukaemia, MDS: Cytopenia
MPN: Cytosis)
Cytosis: 可以係Reactive
Cytopenia: 唔會Reactive)
***Summary of Leukaemia
Acute Leukaemia (最怕Bleeding tendency)
- Treatment: Induction, Consolidation, Maintenance, HSCT
- Treatment of Tumour lysis syndrome
- Blood product support
- Treat any infection
AML: Acute myeloid leukaemia - Leukocytosis - Blasts - Anaemia - Thrombocytopenia
APL: Acute promyelocytic leukaemia (t(15;17), PML-RARa fusion) - Pancytopenia - Anaemia - Bleeding tendencies - DIC - Faggot cell
ALL (B-ALL / T-ALL): Acute lymphoblastic leukaemia - Lymphocytosis - Blasts - Anaemia - Thrombocytopenia
MDS:
Myelodysplastic syndrome (Ineffective haematopoiesis —> Premature apoptosis)
- Pancytopenia
- Hyperplastic BM (Blasts but <20%)
- Dysplastic features in Myeloid, Erythroid, and/or Megakaryocytic lineage(s)
- RBC Macrocytosis
- Treatment
1. Supportive (e.g. transfusion)
2. Erythropoietin-stimulating factors (ESA)
3. G-CSF (for Granulopoiesis)
4. Hypomethylating agents (Azacitidine, Decitabine)
CML: Chronic myeloid leukaemia (t(9;22), BCR-ABL1 fusion) - Leukocytosis —> Bimodal prominence of Neutrophils (Neutrophilia) and Myelocytes —> Basophilia (—> Eosinophilia) - Anaemia - Thrombocytosis - Splenomegaly - Tyrosine kinase inhibitor —> Imatinib
MPN:
Myeloproliferative neoplasms (最怕Thrombosis)
- CML —> Anaemia, ↑ WBC (Bimodal), ↑ Plt
- Polycythaemia Vera (JAK2 V617F) —> ↑ RBC, ↑ WBC, ↑ Plt
- Essential Thrombocythaemia (JAK2, CALR, MPL) —> ↑ Plt
- Primary Myelofibrosis (JAK2, CALR, MPL) —> Anaemia, ↑ WBC, ↑ Plt, Hypercytokinemia, Leukoerythroblastic picture
- Treatment:
1. Antiplatelet for managing risk
2. Cytoreduction (Hydroxyurea and IFN)
3. PV: Phlebotomy (Venesection)
4. ET: Monitor for acquired vWD + Anagrelide
5. PMF: JAK/STAT inhibition (Ruxolitinib)
CMML:
Chronic myelomonocytic leukaemia (CMML)
- Leukocytosis
- Monocytosis
- +/- Anaemia (Dysplastic change in Erythroid lineage)
- +/- Thrombocytopenia (Dysplastic change in Megakaryocyte lineage)
CLL:
Chronic lymphocytic leukaemia
- Lymphocytosis
- Abnormal lymphoid cells
Lymphoma: - B / T cell - Myeloid cell rarely - Treatment: 1. Multi-agent cytotoxic chemotherapy —> Rituximab (Anti-CD20) —> Brentuximab vedotin (Anti-CD30 with MMAE, Immunoconjugate) —> Pembrolizumab (Anti-PD1, Check-point inhibitor) 2. Multiple cycles
***Summary of investigation
基本:
- CBC with manual blood film review + differential count (D/C)
- Diagnostic BM aspiration, Trephine biopsy
- CXR
- LFT, RFT
- Serum electrolytes (K, PO4)
- LDH, urate levels
其他:
- Clotting profile, d-dimer, fibrinogen (***APL)
- Serum protein electrophoresis, ESR, β2 microglobulin, Whole body PET-CT (Lymphoma)
Diagnostic: BM examination: 1. Morphology on PB/BM 2. Cytochemistry 3. Immunophenotype 4. Cytogenetics 5. Molecular genetics
Pre-treatment investigations:
- ECG, transthoracic echocardiogram
- Lung function
- Hepatitis B, C serology
- HIV serology
- G6PD assay
- HLA-typing of patients, siblings for allogeneic HSCT
