Case report: Contact allergy to tapinarof

Psoriasis is a chronic inflammatory skin condition, which is often treated with topical corticosteroids and various topical non-steroidal medications. Tapinarof, a novel therapeutic agent, has shown promising results in the treatment of psoriasis. We report a case of contact allergy to tapinarof. A 55-year-old female presented with a 10-year history of skin lesions on the superior aspect of the intergluteal cleft, diagnosed as psoriasis. The patient had been managing her symptoms with various topical treatments. After starting tapinarof cream (Vtama) (Dermavant Sciences Inc., Long Beach, CA), her rash began worsening and then spread for the first time to the perineum and genital area over the next few days. Patch tests were performed using the 90 allergen 2021 American Contact Dermatitis Society (ACDS) core series and Vtama. IQ ultra chambers (Chemotechnique, Vellinge, Sweden) were applied to the patient's back for 2 days and read at both day 2 and day 4. There was a 1+ reaction to Vtama at day 2, which increased to a 3+ reaction at day 4 (i.e., a crescendo reaction). All other allergens tested were negative. At day 2, there was no oedema, crusting or epidermal disruption at the patch test site (Figure 1). At day 4, oedema exceeded half of the patch test site. There was no crusting or epidermal disruption after the final reading (Figure 2) and none developed thereafter. The vehicle of Vtama was obtained and patch testing yielded negative results at day 2 and day 4, confirming that the reaction to Vtama was due to tapinarof. Patch testing to half-strength Vtama was negative at day 2; however, there was a strong 3+ reaction at day 4. Twenty five control patients tested negative to 1% tapinarof cream at days 2 and 4. We report a case of contact allergy to tapinarof, the active ingredient in Vtama, in a patient with a diagnosis of psoriasis. The Vtama package insert states that the product has caused rashes but does not specifically mention any cases of contact allergy.1 The patient experienced worsening eczema after using tapinarof cream, which then spread to adjacent sites. Although her inflammation worsened shortly after starting tapinarof, she had tried several other topical medications the week prior and there may have been an irritant component to the initial flare up. However, the other topical medications were stopped when tapinarof was started, and the inflammation persisted and then resolved when tapinarof was stopped. Allergic contact dermatitis reactions can occur in patients using tapinarof for the treatment of psoriasis. Clinicians should be aware of this potential adverse reaction and consider patch testing in patients who develop worsening or spreading rashes while using tapinarof. Andrew Scheman: Formal analysis; supervision; validation; funding acquisition; resources; writing – review and editing. Eric King: Supervision; resources; data curation. Lilly Kerchinsky: Visualization; writing – original draft; writing – review and editing; project administration; investigation; methodology. Jack Herbster: Software; conceptualization; writing – review and editing; visualization; investigation; methodology. The authors declare no conflicts of interest.