Abstract
A 29-year-old man complained of a cough of about three weeks' duration, without wheeze or dyspnea. His chest X-ray films showed no abnormality. Laboratory findings were as follows : sputum cytologic findings showed eosinophilia ; methacholine inhalation test by the asthograph method (Chest 80, 600, 1981 : Chest 109, 1525, 1996) was normal (Dmin : 22.5 units) ; and antibody to Mycoplasma pneumoniae (normal : less than 40 times) was elevated to 320 times. Therefore, eosinophilic bronchitis without asthma (Lancet 1, 1346, 1989) was diagnosed, associated with Mycoplasma pneumoniae infection. His cough was treated with a macrolide antibiotic (CAM : clarithromycin) and H_1 antihistamine. After 8 months, the patient again visited our hospital because of a recurrence of chronic cough without wheeze or dyspnea. Antibody to Mycoplasma pneumoniae was elevated to 160 times, suggesting persistent Mycoplasma pneumoniae infection. In addition, he showed hyperresponsiveness to methacholine (Dmin : 18.7 units). At that point, we diagnosed cough-variant asthma. The patient had a favorable response to therapy with pranlukast, a peptide leukotriene receptor antagonist. We speculate that Mycoplasma pneumoniae infection may cause some cases of cough-variant asthma, and we conclude that pranlukast may be useful for the treatment of cough-variant asthma.
