A 14-year-old boy with bullous lesions.

A 14-year-old previously healthy boy presents with a 2-week history of purpuric rash with worsening pain of lower extremities. He has an unremarkable past medical and surgical history, with age-appropriate development. Two weeks prior to presentation, he developed “bug bites” around his ankles bilaterally with minimal pruritis. Over the next 3 days, this rash began to progress to his mid-calves and coalesce into larger purplish lesions. One week prior to admission, he began to have severe abdominal pain forcing him into the fetal position. There was no associated nausea or vomiting with the abdominal pain; however, the episodes of pain would be intense and then gradually resolve. There is no history of fever or joint pain. Family history is noncontributory, and there is no recent travel or sick contacts. There are no known allergies.