Group A β-hemolytic streptococci were isolated from a perineal swab. A streptozyme test was positive at a titer of 1:400, and the antistreptolysin O antibody level was 850 U/L (normal, <250 U/L). The patient was allergic to erythromycin, so oral amoxicillin was administered (50 mg/kg per day) for 10 days, with rapid resolution of the patient's symptoms.
In children, PSD is an underdiagnosed entity. It was first described by Amren et al1 in 1966. Since then, only about 100 cases have been reported. It mainly affects boys (mean age, 5 years; range, 7 months to 12 years). Clinically, it is characterized by well-defined perianal erythema, sometimes associated with mild edema, exudation, pustules, and bleeding. A chronic course can result in fissures and rimmed hyperpigmentation. Functional symptoms include pruritus, tenderness, and pain during defecation. In the female, extension to the vulva has been reported.2 The clinical differential diagnosis includes candidiasis, oxiuriasis, seborrheic dermatitis, psoriasis, inflammatory bowel disease, and sexual abuse. Patrizi et al3 reported 4 cases of PSD in association with guttate psoriasis.
Perianal Dermatitis in a Child. Arch Dermatol. 1998;134(9):1145-1150. doi: