acute lymphoblastic leukaemia
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acute lymphoblastic leukaemiaA malignant lymphoproliferative process, which commonly affects children and young adults, affecting ± 1800/year (US); ± 650/year (UK).
ALL has a hereditary component; it is 20-fold increased in patients with Down syndrome; it is linked to benzene exposure, radiation therapy in ankylosing spondylitis.
Abrupt onset, often ± 3-month history of fatigue, fever, haemorrhage from multiple sites, lymphadenopathy, hepatomegaly, splenomegaly.
Most are B cells and express CD19; 60% have karyotypic abnormalities; the most common cytogenetic abnormality is the cryptic t(12;21) translocation, resulting in TEL-AML fusion (25% of cases), followed by the t(1;19)(q23;p13.3) translocation, seen in 5% of cases.
90–95% achieve remission; improved cure rate is attributed to prophylaxis for meningeal leukaemia and more intense systemic chemotherapy. The current survival ranges from 20% to 75%.
FAB classification, acute leukaemias
Acute lymphocytic leukaemia (ALL)
L1—Small monotonous lymphocytes.
L2—Mixed L1- and L3-type lymphocytes.
L3—Large homogeneous blast cells.