In one study, the incidence was reported to range from one in 218 to one in 2,000 pediatric outpatient visits. 4 Intrafamily spread was reported in 50 percent of possible cases. 4 Prior therapy with topical antifungal agents, topical corticosteroids and oral preparations for pinworms fails to improve or worsens patients' symptoms. This type of therapy frequently leads to a delay in definitive diagnosis and treatment. Children with streptococcal pharyngitis have a 6 percent anal carriage rate.
Physical examination reveals a bright red, sharply demarcated, perianal rash.
Subcutaneous involvement suggestive of cellulitis is normally absent. The absence of fever and systemic signs and symptoms also supports the superficial localization of this rash. Fissures, a mucoid discharge and yellow crusting are sometimes present. The differential diagnosis of perianal streptococcus dermatitis includes diaper dermatitis, candidiasis, psoriasis, seborrheic dermatitis, sexual abuse, pinworm infestation, local trauma from heavy wiping and inflammatory bowel disease. A rapid strep test or a culture of the perianal area may elucidate the diagnosis.