Chronic Leukaemia Flashcards
Chronic Leukaemias
Lymphoid or myeloid
- Clonal malignant proliferations of haemopoetic tissue
Lymphoproliferative disorders
Neoplastic proliferations of mature lymphocytes
- Heterogenous group of disorders including non-hodgkins lymphomas
- Can be further classified into T-cell and B-cell disorders
Diagnosis of Chronic Lymphocytic leukaemia
Morphology
Immunophenotyping
Genetic/molecular analysis e.g. detection of immunoglobulin and T-cell receptor gene rearrangements to demonstrate clonality.
Chronic Lymphocytic Leukaemia (CLL)
- “a progressive accumulation of lymphocytes, starting in the lymph nodes and /or bone marrow and gradually expanding to other haemopoietic organs”.
- B cell Disorder
- Commonly presents in adults over 50 years of age
- 25% of all leukemias, most frequent type in Western Countries
- Often diagnosed coincidentally
- Aetiology unknown: geographical variation, no link with chemo/radiotherapy
- More common in Males ( 2:1 )
CLL Pathogenesis and linked genetic abnormalities
- Mononoclonal B cell proliferation
- Precise cause uncertain
- Cells are long-lived and resistant to apoptosis – thought to be linked to expression of BCL-2.
- 50% of CLL patients carry mutated immunoglobulin heavy-chain variable (IGHV) genes. Unmutated cases associated with worse outcome.
Recurrent genetic abnormalities identified e.g: del 13q14 (most common mutation at diagnosis), del 17p13 , Trisomy 12
- May be an initiating cause that results in disruption of the tumour suppressor genes (TP53).
CLL Clinical Features
Often undiagnosed until routine medical check up.
Symmetrical enlargement of cervical, axillary or inguinal lymph nodes.
Anaemia may be present.
Bruising/purpura if thrombocytopenia.
Splenomegaly (occasionally hepatomegaly) in later stages of disease.
Infections: bacterial, fungal and viral
e.g. herpes zos
CLL Diagnostic Clinical Features
- Clinical features, FBC, morphology and immunophenotyping are important.
- Usually normocytic/normochromic:type of anemia characterized by normal-sized red blood cells (normocytic) with normal hemoglobin concentration (normochromic). Suggests anemia is caused by underlying illness not the size/shape of RBCs.
- AIHA a complication.
Persistent lymphocytosis:Small cells with scanty cytoplasm and characteristic nuclear chromatin clumping, Smear cells.
Lymphocyte count variable - 5.0 x109/L to >200 x109/L
+/- thrombocytopenia, especially in advanced stages.
CLL Diagnostic Feature: Smear Cells
- smear cells typically composed of mature-appearing lymphocytes.
- may observe small, mature-appearing lymphocytes with clumped chromatin and scant cytoplasm.
- cells often appear “smudged” due to their fragility, hence the term “smear cells.”
- not exclusive to CLL but are commonly associated
Ritchers syndrome microscopic features
Large cells: DLBCL cells are typically larger than the small, mature lymphocytes seen in CLL. These cells have a high nuclear-to-cytoplasmic ratio.
Irregular nuclear contours: The nuclei of DLBCL cells often show irregular contours, with vesicular chromatin and prominent nucleoli.
AIHA seenin CLL microscopic features
Spherocytes: Smaller, dense, and round red blood cells that lack the central pallor typically seen in normal red blood cells. They result from the removal of portions of the red blood cell membrane, leading to a more spherical shape.
Polychromasia: This refers to the presence of young, immature red blood cells (reticulocytes) in the peripheral blood. These cells appear bluish in color due to residual ribosomal RNA.
Immunophenotyping and differential diagnosis
- Imunophenotyping allows CLL to be compared to other lymphoproliferative disorders
CLL lymphocytes are B cells e.g. CD19 pos.
CD5 positive- this differentiates CLL from PLL, HCL, FL.
Weak expression of surface immunoglobulin.
Weak expression of surface light chains demonstrates monoclonality.
Only one type of light chain expressed – either K or λ.
Prognosis Factors in CLL
- Females with deletion 13q14 cytogenetics and low lyphocyte (CD38?) expression have a better prognosis than males with trisomy 12, deletion 17p , deletion 11q23 cytogenetics with higher lymphocyte expression.
- CLL May transform to high grade lymphoma with increasing number of lymphocytes and resistance to treatment.
CLL Treatment options
Aimed at controlling symptoms - treatment may not be required though.
Drugs used depend on mutation status, age etc.
Combinations of cytotoxic drugs e.g. chlorambucil, fludarabine, cyclophosphamide.
Monoclonal antibody against CD-20 e.g. Rituximab, atumumab and obinutuzumab.
Corticosteroids.
Radiotherapy.
Immunoglobulins.
Drug options:
- BCL-2 inhibitor
- Suppressed signalling through the B cell receptor e.g. Ibrutinib (inactivates BTK and leads to B cell apoptosis).
Chronic Myeloid Leukaemia
- myeloproliferative Neoplasm
- Clonal disroder resulting from acquired genetic change in pluripotential haemopoietic stem cell
- Accounts 15% of leukaemias
- Occurs in 1-1.5 per 100,000 of the population per annum in all countries
- Any age but rare below 20 with frequency increasing with age.
- Slight male predominance
CML Cytogenetics
- CML- first malignancy to be linked to a clear genetic abnormality
-BCR gene from chromosome 22 is fused with the ABL gene on chromosome 9
-This abnormal “fusion” gene generates a protein the bcr-abl fusion gene( this is a tyrosine kinase)
-Over 90% of cases are bcr/abl positive
-Oncogene binds to interleukin3 receptor
-Continuously active, not needing activation
-Inhibits DNA repeat
-Creating genomic instability
CML Clinical Features
- Often diagnosed incidentally from routine FBC
- Splenomegaly common
-Hypermetabolism – weight loss, lethargy, night sweats.
-Anaemia.
- Bruising/bleeding e.g. epistaxis, menorrhagia due to abnormal platelet function.
-Gout and renal impairment due to raised uric acid from excessive purine breakdown.
- Typically a biphasic or triphasic disease: Chronic phase, Accelerated Phase, Blast Phase
Diagnosis/ Lab Features:
- Raised WBC - usually > 50x10^9/l and occasionally over 500x10 9/l
- complete range of myeloid cells can be seen but matre neutrophils and myelocytes predominate
- Increased basophils
-Nomocytic/normochromic anaemia - Thrombocytosis common ( may be normal or low)
- Bone marrow is hypercellular but blasts less than 5% (increases with progression of disease)
- Molecular studies/karyotype.
CML Progression - Chronic Phase
- Chronic Phase: Ability to reduce spleen size and maintain normal blood count with treatment
CML progression - Accelerated Phase
Defined by one or more of the following:
Blasts 10-19%.
Basophils in blood ≥20%.
Persistent thrombocytopenia unrelated to treatment or thrombocytosis unresponsive to treatment.
Increasing spleen size and WBC unresponsive to treatment.
Megakaryocyte proliferation with marked fibrosis.
CML Progression Blast Phase
Defined by one or more of the following:
-Blasts >20%.
-Extramedullary blast proliferation.
-Large foci or clusters of blasts in the BM.
CML Progression
- typically begins in chronic phase and progresses to the accelerased and blast crisis phase over several years
- Duration of chronic phase is variable with milder and more controllable symptoms. Disease progresses without treatment
- Staging dependent on proprtion of blast cells in the blood/bone marrow
CML Diagnosis
- 90-95% demonstrate the classic Philadelphia chromosome reciprocal translocation: t(9;22) (q34;q11)
- Remaining cases either have variant translocations involving other chromosomes or a cryptic translocation that cannot be identified by routine analysis and requiring further investigations such as FISH and PCR.
Philadelphia Chromosome
-Parts of two chromosomes 9 and 22, swap places creating a elongated chromosome 9 (der 9), and a truncated chromosome 22 (the Philadelphia chromosome).
- p210 BCR – ABL1 oncoprotein has far greater tyrosine kinase activity than the normal ABL1 gene product.
CML Treatment - Glivec
- Imatinib mesylate (Glivec): Tyrosine kinase inhibitor specifically inhibiting BCR-ABL1 fusion protein
- Works by competing with ATP binding and blocking phosphorylation of further molecules.
Rapidly reverses clinical and molecular abnormalities in most patients.
Some patients demonstrate resistance to imatinib, either from the start of treatment or later on.
There are now ‘Second generation tyrosine kinase inhibitors’ e.g. dasatinib, nilotinib and bosutinib.
CML Treatment: Other treatment options
chemotherapy e.g. hydroxyurea
α-interferon
SCT – only chance of cure. However, due to the complication reserved for younger patients and those where tyrosine kinase inhibitors fail.
CML patients receiving therapy are commonly monitored with blood counts, marrow cytogenetics and molecular assays.
CML: Prognosis scroing systems
Sokal, Hasford and EUTOS.
Sokal score is common - takes account of age, blast cell percentage, spleen size and platelet count.
-Response to a tyrosine kinase inhibitor is good prognostic indicator.
