Occupational asthma (OA) with sensitization to diphenylmethane diisocyanate (MDI) presenting at the onset like a reactive airways dysfunction syndrome (RADS).
BACKGROUND
Two types of OA are distinguished: immunological (OA with sensitization) and non-immunological, i.e., irritant induced asthma or reactive airways dysfunction syndrome (RADS).


METHODS
We describe the case of a worker who developed respiratory symptoms after a spill of diphenylmethane diisocyanate (MDI) at the workplace. RADS was initially diagnosed and the worker resumed working. The progressive worsening of symptoms and the appearance of symptoms-work relationship one year later, when concentrations of isocyanates were no longer "irritant," suggested immunological OA.


RESULTS
The diagnosis was confirmed by specific inhalation challenge test, followed by removal from exposure and complete recovery.


CONCLUSIONS
In the case of RADS due to an agent with both irritant and sensitizing properties, history should be repeatedly assessed for a possible symptom-work relationship. If this is found, further investigations should be carried out, including specific inhalation challenges, to confirm the possibility of immunological OA.
Perfetti
Luca
L
Servizio Autonomo di Allergologia e Immunologia Clinica, Fondazione S. Maugeri, Clinica del Lavoro e della Riabilitazione, IRCCS, Istituto Scientifico di Pavia, via Ferrata 8, 27100 Pavia, Italy. lperfetti@fsm.it
Bramé
Barbara
B
Ferrari
Massimo
M
Moscato
Gianna
G
D001249:Asthma / Q000139:chemically induced* / Q000175:diagnosis; D003937:Diagnosis, Differential; D004342:Drug Hypersensitivity; D005260:Female; D006801:Humans; D007221:Industry; D017953:Isocyanates / Q000506:poisoning*; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000175:diagnosis; D012130:Respiratory Hypersensitivity / Q000139:chemically induced* / Q000175:diagnosis; D001559:Benzhydryl Compounds
D017953:Isocyanates; C005969:4,4'-diphenylmethane diisocyanate; D001559:Benzhydryl Compounds