The most common cause of perianal itching in childhood is perianal
dermatitis or infection. Pruritis after a course of broad-spectrum
antibiotics is common and probably results from cutaneous overgrowth
of Candida. Atopic dermatitis, seborrhea, contact
dermatitis, perianal streptococcal infection, psoriasis, anal fissures,
and lichen sclerosus et atrophicus cause pruritis. Culture or biopsy
of the perianal skin may be necessary to identify rarer conditions
when conservative therapy fails. Fecal or urinary incontinence or
poor hygiene may cause maceration and dermatitis of the perianal
skin with pruritus. Parasites such as pinworms, tapeworms, Trichomonas,
scabies, and body lice may cause perianal pruritis. Diabetes mellitus,
uremia, cholestatic liver disorders, urinary tract infection, and
vaginitis all cause perineal itching. Foods containing chemical
irritants or histamine releasers such as coffee, tea, wine, chocolate,
colas, citrus, rhubarb, tomatoes, and peppers may cause irritation
of the perianal skin during defecation. Perianal scratching may
be a symptom of anxiety. Lichenification of the perianal skin by
scratching perpetuates the sensation of pruritis.