By Gary M. White, MD
Some adults, especially men, may complain of chronic perianal pruritus. The diagnosis of pruritus ani should only be made in the absence of clinical findings. Chronic diarrhea or fecal incontinence (stains on the underwear?) may cause an irritant contact dermatitis. Physical examination should try to exclude lichen simplex chronicus, psoriasis, hemorrhoids, candidiasis, seborrheic dermatitis, erythrasma, allergic contact dermatitis, fungal infection and even pinworms. Culturing the skin to exclude Beta Streptococcus may be done. Subclinical irritation may explain why irritation and itching occur in the absence of obvious skin changes. Over washing, retained heat, and feces left on hair are potential contributing factors. Some have considered that spicy foods may make residual feces more irritating. In a child with pruritus ani, pinworms may be excluded with the early morning Scotch Tape test. Finally, in the absence of any other cause, pruritus of neurologic origin may be considered (similar to notalgia paresthetica and meralgia paresthetica).
Any prolonged exposure of feces to the skin must be avoided! Wash with water and mild soap after bowel movements. Rinse, and then dry with a towel. Some have advocated cotton applied to the perianal area to prevent spray with flatus. If constant moisture from sweating is a problem, a super absorbent powder may be used. Some have recommended dietary alterations such as avoiding spicy foods. Allergic contact dermatitis should be excluded by the avoidance of potential allergens, e.g. neomycin, benzocaine. Lidocaine HCL 3% cream (Lida Mantle in the US) may be tried. It is applied 2-3/day.
If no obvious cause is found, a trial of a topical steroid e.g. triamcinolone for one week should be given. Topical doxepin or topical tacrolimus may be tried.
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