A previously healthy 24-year-old Chinese male presented to the emergency department because of a very itchy rash that had evolved in two days. He denied any systemic symptoms or exposure to medication. Physical examination revealed multiple linear erythematous lesions composed of petechiae. The lesions were located primarily on the back (figure 1), chest, and proximal areas of the lower limbs. There was no dermographism. The mucosal surfaces were normal.