This 4-year-old child had intense pruritus. What is the diagnosis?
1. Bacterial dermatitis
2. Pilonidal abscess
4. Scarlet fever
5. Sexual abuse
There is a sharply demarcated area of erythema around the anus without any satellite dermatitis. A swab of the infected area was obtained for a rapid Streptococcus pyogenes antigen test, and the results were positive. A 7-day course of penicillin V was successful.