(Cancer)

Overview

Uncontrolled proliferation of immature WBCs that then accumulate in the blood or bone marrow.

• Acute Lymphoblastic Leukaemia (ALL)
  • Most common malignant disease in children, peak incidence 2-5 years old
  • No identified cause or risk factors in most cases, however Down Syndrome increases risk
• Acute Myeloid Leukaemia (AML)
  • More common in adults, peak incidence 65 years old
  • Pre-existing haematopoietic disorder is most common cause → aplastic anaemia, myeloproliferative disorders (eg. polycythaemia vera).
    • 1/3 of Myelodysplasia progressses to AML
  • Also associated with Down Syndrome
  • Auer Rods on cytology → large pink/red stained needle-like structures

• Chronic Lymphocytic Leukaemia (CLL)
  • Low-grade B-cell lymphoma caused by a monoclonal proliferation of well-differentiated lymphocytes which are almost always B-cells (99%)
  • M>F, median age at diagnosis is 70-72 years old (most common type of leukaemia in adults)
  • Richter Transformation into non-hodgkin’s lymphoma (presents with lymph node swelling, fever, weight loss, night sweats)
  • Smudge Cells → remnants of cells that have no identifiable plasma membrane or nuclear structure
• Chronic Myeloid Leukaemia (CML)
  • Overexpression of cells of myeloid lineage, especially granulocytes
  • Peak incidence at 50-60 years old
  • Philadelphia Chromosome → reciprocal translocation between chromosome 9 and chromosome 22. The resulting BCR-ABL gene codes for a fusion protein that has tyrosine kinase activity in excess of normal.

Making Diagnosis

Clinical Features:

• Acute Leukaemia
  • Sudden onset of symptoms
  • Anaemia → fatigue, pallor, weakness
  • Thrombocytopenia → epistaxis, bleeding gums, petechiae, purpura, easy bruising
  • Frequent Infections → due to immature leukocytes and leukopenia
  • Hepatosplenomegaly
  • ALL ⇒ Lymphadenopathy and Fevers (Not AML) ⇒ DISTINGUISHING
• Chronic Lymphocytic Leukaemia → many cases remain asymptomatic for long period, leading to late diagnosis. B symptoms (weight loss, fever, night sweats), painless lymphadenopathy (more marked than CML), recurrent infections (due to hypogammaglobulinaemia), symptoms of anaemia (warm AIHA, IgG) and thrombocytopenia, pruritus.
• Chronic Myeloid Leukaemia → weight loss, fever, night sweats, massive splenomegaly, anaemia, hyperviscosity symptoms (increased thrombotic risk)

Investigations:

• Acute Leukaemia
  • FBC (ALL + AML) → neutropenia, thrombocytopenia, anaemia
  • Peripheral Blood Smear → presence of blast cells (immature WBCs)
  • Bone Marrow Aspiration & Biopsy → confirm diagnosis. Hypercellular marrow with >20% of cells being lymphoblasts (ALL).