Leukaemia

Question 1

what is leukaemia

Answer 1

cancer of the white blood cells

is a group of disorders characterized by the accumulation of malignant white cells in the bone marrow and peripheral blood

leukaemia is a disease resulting from the neoplastic prolieration of a single stem cell - this transforming cell may be a myeloid or lymphoid precursor

develops as a consequence of the loss of a control mechanism

• increase in proliferation rate
• loss of apoptotic control

affects the ability to produce normal blood cells

Question 2

what are the four types of leukaemia

Answer 2

chronic and acute then lymphoid or myeloid

Question 3

what is acute leukaemias

Answer 3

usually more aggressive

dominant clincal feature is usually bone marrow failure caused by accumulation of blast cells (a stage in the development that can be morphologically identified)

characterosed by a defect in maturation, leading to an imbalance between proliferation adn maturation; since cells of the leukaemic clone continue to proliferate without maturing to end cells and dying, there is continued expansion of the leukaemic clone and immature cells predominate

if untreated - fairly rapidly fatal (weeks or months)

paradoxically- easier to cure than chronic leukaemias

Question 4

whats the classification of chronic leukaemias

Answer 4

distinguished from acute by their slower progression

more difficult to cure than acute

if untreated - lead to death in months or years

characterised by an expanded pool of proliferating cells that retain their capacity to differentiate to end cells

Question 5

what are the main types of leukaemia

Answer 5

ACUTE
Acute lymphoblastic leukaemia (ALL) Lymphoblasts in both bone marrow and blood

Acute myeloid leukaemia (AML) Usually myeloblasts. Sometimes promyelocytes,
monoblasts, or promonocytes. Occassionally erythroblasts, and rarely megakaryocytes. FAB classification

CHRONIC
Chronic myeloid leukaemia (CML) Neutrophil myelocytes, metamyelocytes and neutrophils

Chronic lymphocytic leukaemia Lymphocytes

OTHER
Acute biphenotypic leukaemia
Chronic granulocytic leukaemia (CGL)
Chronic myelomonocytic leukaemia (CMML)
Hairy cell leukaemia (HCL)
Prolymphocytic leukaemia (PLL)
Plasma cell leukaemia (PCL)

Question 6

what can cause leukaemia

Answer 6

Inherited factors (genes)
-Some genetic diseases can predispose individuals to haematological malignancies e.g. -Down’s syndrome, where acute leukaemia occurs with a 20 - 30 fold increased frequency

Environmental influences

• Chemicals : many polycyclic and aromatic hydrocarbons are carcinogenic e.g. benzene is a well established leukaemogen – AML has the strongest association
• Radiation : 1945 atomic bombs in Nagasaki and Hiroshima, mostly associated with acute leukaemia and chronic myeloid leukaemia
  - treatment for solid tumours – secondary leukaemias
  - occupational exposure in medical radiology
  - radiation scientist (nuclear processing plants) e.g. Marie Curie and her daughter

Infection
Viruses e.g. Epstein-Barr virus (EBV), human T-cell leukemia-lymphoma virus-I (HTLV-I)
Bacteria

Exactly how genetic mutations accumulate in haemopoeitic malignancies is largely unknown, however, in the majority of individual cases no genetic, environmental or infection is the apparent cause

Question 7

what are the symptoms of leukaemia

Answer 7

Pallor, lethargy – often attributed to anaemia
Recurrent infections – dysfunctional immune system
Easy bruising – reduced platelets (thrombocytopenia)
Pyrexia, night sweats, flu-like symptoms, weight loss – malignant B-lymphocytes in response to synthesis and secretion of cytokines
Bone pain – increase in BM cellularity
Lymphadenopathy
Splenomegaly, hepatomegaly – enlarged spleen and or liver

Question 8

what is chronic lymphatic leukaemia

Answer 8

Blood cells are normally produced in a controlled way, but in leukaemia the process gets out of control. The lymphocytes multiply too quickly and live too long - hence too many circulating in the peripheral blood.

There is a reduction in the number of normal B-lymphocytes resulting in a reduced ability to make antibodies.

There is also a an increase of suppressor T cells and a reduction in the number of helper T cells which probably accounts for the impairment of cell mediated immunity (CD4:CD8 ratio).

Question 9

what is acute lymphablastic leukaemia

Answer 9

ALL : Malignant tumour of haemopoietic precursor cells of the lymphoid lineage probably arising from the BM in most cases. Results in the accumulation of lymphoblasts.

Incidence : The common form of leukaemia in children; its incidence is highest at 2 – 5 years (median 3.5), falling off by 10 years of age. There is a secondary rise after the age of 40 although this is still a rare leukaemia in adults ~ 1 in 70,000 annually i.e. ~7 times less common than AML.

The common (CD10+) precursor B-type has an equal sex incidence. There is a male predominance for T-ALL.