Cough variant asthma: a case study with antigen, histamine and methacholine inhalation challenge tests.

This paper presents a 7 year old girl with cough variant asthma, in which house dust challenge test provoked fine crackles on auscultation without any changes of lung function test. Pretreatment with DL-chlorpheniramine maleate for 7 days inhibited the appearance of fine crackles. On histamine inhalation test, fine crackles and rhonchi appeared on auscultation without bronchoconstriction (% fall of one-second forced expiratory volume < 10%). These data suggest that the cause of cough variant asthma is mainly an immunoglobulin E-mediated allergic reaction in the mucus secreting system.