The clinical manifestations of acute leukaemia depend on the level of leukaemic infiltration into the marrow and extramedullary sites at the time of presentation, resulting in a wide spectrum of signs and symptoms. It is important to recognise parental and carer concern and the need to escalate investigations, particularly after repeated visits to healthcare professionals.

The following signs and symptoms may warrant consideration of a full blood count and peripheral blood film examination:

• persistent unexplained fever
• diffuse bone pain with no obvious trauma and/or refusal to walk in children
• generalised lymphadenopathy
• hepatosplenomegaly
• pallor
• unexplained bruising, unexplained bleeding or petechiae
• extreme fatigue
• recurrent

Children can sometimes have only mild symptoms, so the medical practitioner should be alert to the diagnosis, particularly when there is a constellation of the symptoms/signs as described above.

Rarely, leukaemia can manifest itself without an abnormal full blood count. Signs and symptoms include testicular swelling in males (testicular involvement with CAYA acute leukaemia) or isolated neurological symptoms such as cranial nerve palsies/headaches (central nervous system [CNS] CAYA leukaemia).