Prolonged Exposure Dermatosis: Reporting High Incidence of an Undiagnosed Facial Dermatosis on a Winter Wilderness Expedition.

OBJECTIVE: Previously unclassified inflammatory skin lesions referred to as sun bumps have been observed throughout the year on participants of wilderness trips; however, the underlying cause and diagnosis remain unclear. The purpose of this prospective observational study was to document the incidence, characteristics, and risk factors associated with these skin lesions as they occurred on a winter wilderness expedition.

METHODS: For this study, the lesions were defined as pruritic or erythematous skin lesions occurring while in the wilderness. Seventy-four participants in a wilderness ski touring course in Wyoming fully completed a 44-question written survey concerning occurrence and risk factors for these lesions. Weather information and photographs were collected.

RESULTS: Twenty-six percent of participants had similar lesions. The lesions were described as edematous pale papules and plaques with erosions and crusts on an erythematous background. The face was involved in 90% of affected persons. Lesions occurred after an average of 8.7 days in the wilderness and resolved 10.6 days later. Skin that was less prone to sunburn was associated with a decreased incidence (odds ratio 0.44). No association could be found between lesion incidence and history of polymorphous light eruption, sun exposure, ambient temperature, affected contacts, sex, or body mass index.

CONCLUSIONS: Overall, the lesions were common among study participants but occurred only after prolonged exposure to wilderness conditions. It was not possible to classify the skin condition as an example of any known diagnosis. We propose the name "prolonged exposure dermatosis" for this condition until further studies better define its etiology, prevention, and treatment.