Potty-training seats may be to blame in toddlers presenting with pruritic rash on their buttocks and upper thighs. In such cases, be on the alert for contact dermatitis, reported Claire O. Dorfman, DO, of Lehigh Valley Health Network, Allentown, Pa., and her associates at Hershey (Pa.) Medical Center.

A 3-year-old white boy with a 6-month history of a pruritic rash on his buttocks and bilateral posterior thighs was treated without improvement at the pediatric dermatology clinic with low-potency topical corticosteroids, as well as topical antibiotic and antifungal agents.

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Although the pattern of the multiple erythematous, scaly symmetrical plaques appeared atypical and not specific, the clinicians suspected contact dermatitis. Their report was published in the Journal of Pediatric Dermatology. Response was initially achieved with triamcinolone 0.025% cream twice daily, but the rash worsened and recurred after treatment concluded. Despite more aggressive treatment with fluocinonide 0.05% ointment twice daily, alternated with tacrolimus 0.03% ointment, and later augmented with betamethasone dipropionate 0.05% ointment twice daily from frequent flares, relief was not achieved.

Only mild improvement was seen once disposable paper toilet seat covers were added to treatment regimen. Following the purchase of a new potty seat through an online retailer, the child’s mother discovered a number of consumer product reviews also detailing similar complaints about the manufacturer, Prince Lionheart WeePOD Basix, by more than 30 other consumers. Photos highlighting identical rash presentation in other toddlers confirmed that the toilet seat was responsible for the allergic reaction. A warning had been posted by the manufacturer but this warning was not provided by the online retailer.

Use of the seat was immediately discontinued, and complete resolution of lesions was achieved within 1 month; subsequently, a report to the Consumer Product Safety Commission was made.

Allergic contact dermatitis to toilet seats is becoming increasingly common, the authors noted. Although the source of allergies is varied, wood historically has been identified as the most common material associated with the condition. Polypropylene and polyurethane foam also have been found to cause irritation. However, in the case reported by Dr. Dorfman and her associates, the precise irritant could not be identified because of the atypical pattern of the lesions and their irregular presentation on the buttocks and thighs. They speculated that this irregularity could be attributed to “the small, round shape of the seat and the squirmy behavior of a toddler,” because the typical arciform distribution was not present. Relief was not achieved with the paper liners because they did not completely cover the seat.

Because the rash resolved when the seat was replaced, parents declined patch testing. As a result, it was not possible to identify the specific allergenic component of the polyurethane. The polyurethanes used to make the seats are synthetic polymers that contain isocyanates, and frequently diaminodiphenylmethane, a curing agent. Possible allergy to the dyes used during manufacture also was considered but the presenting rash was reported in all four of the available colors made.

Although it was speculated that exposure to cleansers could be to blame for possible irritant dermatitis given reports of cracking of the potty seat, the mother and several online reviews indicated only soap and water were used, not harsh cleaning agents.

The clinicians had no relevant financial disclosures.

SOURCE: Dorfman CO et al. Pediatr Dermatol. 2018 May 29. doi: 10.1111/pde.13534.

Consider potty seats when you see contact dermatitis on toddler bottoms