Cough-variant asthma: a diagnostic dilemma in the occupational setting

Cough-variant asthma (Corrao's syndrome) is defined as the presence of chronic non-productive cough in patients with bronchial hyperresponsiveness (BHR) and response to bronchodilator therapy. This variant of asthma may present a diagnostic problem in occupational medicine.

To describe additional evaluation of cough-variant asthma in a cyanoacrylate-exposed worker in whom standard diagnostic testing was negative.

A female beautician was evaluated for suspected occupational allergic rhinitis and asthma. A specific inhalation challenge test (SICT) was performed with cyanoacrylate glues used for applying artificial eyelashes and nails. Spirometry and peak expiratory flow (PEF) measurements were recorded hourly for 24h; methacholine challenge testing was performed and nasal lavage (NL) samples were analysed for eosinophilia.

After SICT, the patient developed sneezing, nasal airflow obstruction and cough. Declines in forced expiratory volume in 1 s and PEF were not observed. Eosinophil proportions in NL fluid increased markedly at 4 and 24h after SICT. A significant increase in BHR also occurred 24h after SICT.

Clinical symptoms, post-challenge BHR and increased NL eosinophil counts confirmed a positive response to SICT and validated the diagnosis of cough-variant occupational asthma. SICT may be useful in cases where history and clinical data suggest cough-variant asthma and spirometric indices are negative.