What is Causing This Man’s Persistent Perianal Dermatitis?

A 58-year-old man presented to dermatology with a 23-month history of perianal dermatitis. This began after completing several courses of oral antibiotics and systemic steroids for sinusitis. Initially diagnosed as candidiasis, he used several topical antifungals as well as oral fluconazole and topical steroids. He noted that only topical steroids seemed to help.

Exam by a gastroenterologist indicated no rectal pathology. His dermatitis progressed, with worsening erythema, erosions, and exudates. He was treated with additional topical steroids and local phototherapy. He also developed blisters on the right palm and fingers. 

Due to the recalcitrant dermatitis, he underwent testing. Skin biopsy revealed dermatitis with eosinophils, suggestive of allergy. Patch testing confirmed allergy to several allergens, including methylchloroisothiazolinone/methylisothiazolinone, also known as Kathon CG (Figure). 

(Answer and podcast on next page)

Answer: Allergic contact dermatitis to moistened toilet paper wipes 

Treatment

The patient was advised to stop using moistened toilet paper wipes. When asked to do so previously, he had concluded that these were an unlikely culprit. He had used wipes for years, and had started use before the dermatitis began. When he now stopped, he noted significant improvement within 10 days. The allergen methylchloroisothiazolinone/methylisothiazolinone, also known as Kathon CG, is a preservative. A review of the patient’s products confirmed that this preservative was present in his toilet paper wipes, which he had been handling with his right hand and using in the perianal area.

This preservative is found in a wide variety of personal care products, including many wipes, such as toilet paper, diaper, and makeup remover wipes.¹ Since wipes are moistened, they require preservatives due to the presence of water. 

Discussion

Preservatives are a common cause of allergic contact dermatitis, due to their required use in so many personal care products. Skin inflammation results in impairment of the skin barrier, which in turn increases the risk of a secondary allergy. In the perianal region, irritant contact dermatitis may result from a non-specific, pro-inflammatory, innate immune response to the fecal enzymes of residual stool. Subsequent repeated exposure to the ingredients in skin care products may eventually lead to sensitization, resulting in a delayed-type hypersensitivity reaction mediated by hapten-specific T-cells, known as allergic contact dermatitis.² Patch testing is the gold standard for identifying the allergens responsible for allergic contact dermatitis. A number of substances may serve as potential allergens, including common allergens such as fragrance additives and preservatives found in cleansers, soaps, and creams. In anogenital dermatitis, another common category is topical medications, specifically anesthetics and steroids.³

Kathon CG has been well-recognized in Europe for years as an important causative allergen in anogenital dermatitis. In the 1990s, positive reactions to methylchloroisothiazolinone were seen more frequently in patients undergoing patch testing specifically for anogenital dermatitis as compared to the total population undergoing patch testing.⁴ In a North American population with anogenital dermatitis tested during the years 1994-2004, by contrast, Kathon CG was not found to be a more prevalent allergen.³

However, as cultural practices and product formulations change, more reports are describing allergy to this preservative in the United States.¹ Anecdotally, some patients report using moistened wipes to help perianal skin complaints, due to concern that residual stool may be playing a role.

Differential Diagnosis

Allergic contact dermatitis must be differentiated from other causes of perianal dermatitis.

• Irritant contact dermatitis (ICD): Residual stool in the perianal region, sometimes associated with diarrhea or rectal pathologies such as hemorrhoids or fistulas, contains fecal enzymes that may cause skin breakdown and ICD. Exposure to chemical or physical irritants concurrent with negative patch testing establishes the diagnosis of ICD.
• Infection: Yeast (Candida) or bacterial (particularly group A Streptococcus) causes of perianal dermatitis affect both adults and children, and are usually responsive to antifungal or antibiotic treatment, respectively.
• Drug-induced atrophy: Atrophy of the skin due to long-term application of topical steroids can present clinically as dermatitis of the perianal region. Medication discontinuation prevents further exacerbation of atrophic changes, and dermatitis may improve slightly with time. 

Our patient’s dermatitis in both the perianal region and the right palm and fingers, combined with eosinophilic infiltrates on biopsy, suggested a contact allergy as the cause of this localized, persistent skin rash. This was confirmed by patch testing and identification of the culprit allergen as Kathon CG, contained in toilet wipes applied to the perianal region.

In cases of recalcitrant perianal dermatitis, therefore, allergic contact dermatitis must be in the differential diagnosis. Potential triggers include seemingly innocuous products, such as moistened wipes. With correct identification, removal of the offending agent may provide clearance, in some cases without the need for any further therapy.

Hear details from the case's author in the podcast below:

References:

1.     Gardner KH, Davis MD, Richardson DM, Pittelkow MR. The hazards of moist toilet paper: allergy to the preservative methylchloroisothiazolinone/methylisothiazolinone. Arch Dermatol. 2010;146(8):886-890.
2.     Nosbaum A, Vocanson M, Rozieres A, et al. Allergic and irritant contact dermatitis. Eur J Dermatol. 2009;19(4):325-332.
3.     Warshaw EM, Furda LM, Mailbach HI, et al. Anogenital dermatitis in patients referred for patch testing: retrospective analysis of cross-sectional data from the North American Contact Dermatitis Group, 1994-2004. Arch Dermatol. 2008;144(6):749-755.
4.     Bauer A, Geier J, Elsner P. Allergic contact dermatitis in patients with anogenital complaints. J Reprod Med. 2000;45(8):649-654.