Samar, a 3-year-old boy, was brought to the pediatrician by his mother because of a rash on his lip. It started 4 days earlier as a little bump above his lip that spread to the corner of his mouth. The base of the rash was red and covered by pustules. The little boy said that his rash hurt, and the clinician noticed a honey-colored crust on the ruptured pustules. Samar’s mother said her son had not been trying to scratch the rash. The physician diagnosed this as impetigo. The doctor gently swabbed a sample from one of Samar’s sores and sent it to the lab, where the causative agent would be identified and its antibiotic susceptibility determined. She explained that impetigo is a very contagious disease and she gave Samar’s mother a topical antibiotic to use.
What is/are the closest differential diagnosis for this condition?
a) Contact dermatitis and herpes simplex
b) Measles and German measles
c) Chickenpox