Test your knowledge. Patient with a skin rash

A fit and healthy 22 year old of Asian ancestry, living in New Zealand with no previous history of asthma or dermatitis, visited the Gold Coast, Queensland, for a vacation. Having been cautioned about the intensity of the Australian sun, he arrived armed with a hat and new SPF130 sunscreen that he had obtained from Japan. On the third day of his vacation he noticed the appearance of many erythematous papules and some vesicles on the dorsum of the forearm, arm and the 'v' of the neck. His face was spared. On the fourth day, the papules coalesced to form swollen, warm, very pruritic, erythematous plaques (Figure 1). The patient commenced taking loratadine 10 mg per day, but did not improve after seven days of treatment.