[Definition, classification and differential diagnosis of childhood asthma].

The pathophysiology of childhood asthma has not been clarified compared to that of adults. Airway remodeling has been demonstrated even in younger children. On the other hand, high incidence of remission compared to that in adults has been shown, suggesting a het- erogeneity of childhood asthma. The diagnosis of childhood asthma is difficult because air- ways of younger children is easy to close, causing wheezing. Thus, differential diagnosis is important. The phenotypes of asthma in younger children is mainly classified into mild episodic viral wheeze and multiple-trigger atopic wheeze.