A healthy young girl presented in June 2014 with a 4-week history of a painless, enlarging lesion on her right thumb that started as a small erythematous blister. She reported recently injuring her hand on a metal fence at home and biting her nails frequently. She lives on a farm in Ohio and has extensive direct contact with sheep and cows; family pets include a cat, a dog, and a hamster. There was no known recent travel or contact with anyone with a similar lesion. She reported mild tender lymphadenopathy of the right axilla but denied fever.