A rash on a woman who rides horses in the winter

A 32-year-old white woman who has never smoked presents with pruritic, tender, erythematous, violaceous patches with eczema-like blisters on her upper, lateral thighs. In 2012, she began traveling annually from Pennsylvania to South Carolina, from January through April, where she works with and rides horses daily from morning to evening. Her symptoms began in her first year in South Carolina ...