Acute lymphocytic (lymphoblastic or lymphatic) leukaemia (ALL) is the most common form of leukaemia (cancer of one type of white blood cell) in childhood and usually starts between three and seven years of age, but only 33 in every one million children will develop any form of leukaemia. 20% of this type occurs in adults. It is now believed that the seeds of this form of leukaemia develop in the foetus but only activate in later life due to unknown stimuli.
Tiredness, recurrent infections, bruising, nosebleeds and bleeding from the gums are the main symptoms. Children develop progressively more severe infections, including skin infections, abscesses and pneumonia. Bleeding into joints may cause arthritic pains, and the liver, spleen and lymph nodes in the neck, armpit and groin may be enlarged. The child may become very ill with multiple serious infections. The diagnosis is confirmed by blood tests and taking a biopsy of bone marrow.