Pustular psoriasis and the Köbner phenomenon caused by allergic contact dermatitis from zinc pyrithione‐containing shampoo

Abstract

Zinc pyrithione is a shampoo ingredient that has been shown to be safe and effective for dandruff and scalp psoriasis. It is thought to decrease the cell turnover rate in hyperproliferative dermatoses such as psoriasis, and also has fungistatic and antimicrobial activity, although its exact mode of action is unknown. In psoriasis, external factors, such as trauma, infection and drugs, may provoke aggravated manifestations of psoriatic skin lesions. Rarely, irritant or allergic mechanisms are likely causes of psoriatic flare and Kobnerization. A patient had had stable psoriasis for 25 years and no any other skin disease. Within 20 days, she developed an aggravated scaly erythematous patch on the scalp, where a shampoo had been applied, and simultaneously developed pustular psoriasis on both forearms. Patch testing showed a relevant sensitization to zinc pyrithione, and we observed symptomatic aggravation by provocation testing with zinc pyrithione shampoo. We report a rare case of psoriasis aggravated by the induction of allergic contact dermatitis from zinc pyrithione after using antidandruff shampoo.

Contact Sensitivity in Patients with Psoriasis in Vojvodina

“…Moreover, many authors indicated that the location of the disease (e.g. palmoplantar and flexural), extreme itching, clinical presentation (predominance of erythema over scaling), long duration, resistance to therapy, and aggravation after topical treatment may suggest the presence of an underlying trigger in the form of a contact agent [13,14,15, 17]. Contrary to these, in the report by Angelini et al [18], only 3.2% of patients with psoriasis who were patch tested to standard allergens and topical medicaments were PT positive.…”

Dandruff: The most commercially exploited skin disease

“…Excessive exposure to sunlight is known to cause desquamation of the scalp[1920] Minimal irritation of scalp due to over shampooing, frequent combing, use of certain cosmetic products, dusts and dirt also, to some extent, cause dandruff. However, there is no sufficient experimental evidence to the above assumptions.…”

Characterization of the Fungal Microbiota (Mycobiome) in Healthy and Dandruff-Afflicted Human Scalps

“…Dandruff is a common scalp disorder affecting almost half of the postpubertal population regardless of ethnicity and gender and has several putative causes including non-microbial and microbial factors [1]–[3]. The potential non-microbial causes for dandruff are excessive exposure to sunlight, minimal irritation of the scalp due to over shampooing, frequent combing, use of certain cosmetic products, and exposure to dust and dirt, although experimental evidence is lacking[1], [4], [5]. The microbial etiopathology that is most widely accepted is the presence of a lipophilic yeast belonging to the genus Malassezia [1], [6].…”