Which of the following represents the most important step in the pathogenesis of the sensitization phase of injury in this patient?

USMLE USMLE 1
#1

A 20-year-old man presents to his family physician for treatment of itching after exposure to poison ivy. The patient’s hands and arms appeared red and were covered with oozing blisters and crusts (shown in the image). Which of the following represents the most important step in the pathogenesis of the sensitization phase of injury in this patient?

image

  1. Development of spongiosis
  2. Infiltration of the epidermis by neutrophils
  3. Migration of Langerhans cells into dermal lymphatics
  4. Rapid increase in vascular permeability
  5. Separation of the epidermis from the dermis mediated by eosinophils