[A case variant asthma with acetylcholine inhalation challenge test].

A 55-year-old male presented with a chief complaint of exertional dyspnea. He had a daughter suffering with bronchial asthma. He had no pertinent past history. He visited the outpatient clinic of a nearby hospital for evaluation of exertional dyspnea, but routine examination results were normal. He was therefore followed up for only about two weeks without treatment. He was sent to our hospital for further analysis. Physical examination revealed clear lung fields but his respiratory rate was 34 per a minute, PaO2 72.9 mmHg and PaCO2 39.7 mmHg. Respiratory function tests, chest XP, chest CT and ECG findings were unremarkable. Pulmonary infarction was ruled out with a pulmonary perfusion scintigram. However, he was hyperreactive to the acetylcholine inhalation challenge test, the respiratory threshold being 625 micrograms/ml. A variant form of bronchial asthma was thus suspected and a bronchodilator was administered. The medication was very effective. After several weeks, his symptoms had clearly disappeared. Therefore, in a case complaining of exertional dyspnea only, bronchial asthma should be ruled out as a possible cause and the acetylcholine inhalation challenge test might be helpful in making the correct diagnosis. Bronchodilator administration should also be considered.