[Occupationally-induced contact dermatitis and bronchial asthma in a unusual delayed reaction to hydroxychloroquine]

We report the case of a a 60 year-old worker in the pharmaceutical industry who suffered from recurring contact dermatitis. Initially the contact dermatitis was limited to the hands; later on it became generalized. The patient had been working on a drug filling line in a pharmaceutical plant for more than 20 years. Eight years after starting this job he had developed allergic hand dermatitis to 2,6-diaminopyridine (patch test positive); this healed upon cessation of exposure. Ten years later he again developed hand dermatitis which progressed to generalized dermatitis and conjunctivitis. Under systemic and local therapy with corticosteroids and cessation of work, it healed nearly completely. Four months after returning to work, the patient experienced a first episode of severe asthma and generalized dermatitis with conjunctivitis following exposure to hydroxychloroquine the day before. The asthma and dermatitis improved after systemic corticosteroid therapy and stopping work. His condition continued to fluctuate, when though the patient was transferred at work and now wore rubber gloves. Eight months later he again developed a generalized dermatitis. Patch testing revealed delayed-type sensitizations to hydroxychloroquine (tested in concentrations of 0. 1%, 0.5%, 1% and 2%). Equivalent tests in five healthy volunteers were negative. The patch test reactions were pustular, while a biopsy was interpreted as a multiform contact dermatitis reaction. Bronchial exposure with hydroxychloroquine dust produced a delayed bronchial obstruction over the next 20 hours, which progressed to fever and generalized erythema (hematogenous contact dermatitis). After removing exposure to 2,6-diaminopyridine and hydroxychloroquine, the patient went on to develop a contact dermatitis to latex (patch test positive). However, skin prick tests with latex and patch tests with rubber additiva were negative. Hydroxychloroquine is well known to cause drug reactions. To our knowledge, contact dermatitis to this substance has not yet been reported. It is noteworthy that the patch test reactions were pustular and of multiform morphology and that bronchial exposure to the allergen resulted in asthma and a generalized drug reaction. Pathogenetically the asthmatic reaction seems to be on a delayed-type mechanism as is also seen with ampicillin, cobalt and nickel induced asthma.