Leukaemia presenting as respiratory distress in a child with asthma.

Asthma is the most common reason for children to present to an emergency department complaining of shortness of breath. The diagnosis, based on one or more of a positive history of atopy, physical examination findings consistent with reactive airways disease, and a clinical response to bronchodilator therapy is usually straightforward. It is important however, to consider other diagnoses, particularly when patients present differently from that which has previously been documented and/or have unexplained physical findings.