BI03 An out-of-place mucosal virus causing cutaneous crisis: a rare case of disseminated human papillomavirus-6 infection during upadacitinib therapy for atopic dermatitis

Abstract

The use of highly effective biologics and small molecules for atopic dermatitis (AD) has introduced new patterns of cutaneous immunosuppression. While systemic agents like Janus kinase inhibitors provide excellent skin barrier control, they can inadvertently lower the threshold for viral acquisition and spread. This is particularly relevant in patients with AD, where pre-existing barrier dysfunction and chronic excoriation predispose to viral inoculation. We describe an unusual case of explosive, disseminated cutaneous human papillomavirus (HPV)-6 infection occurring during upadacitinib therapy and highlight the implications for viral surveillance in immunosuppressed cohorts. We report a 23-year-old transgender man with severe AD who developed a rapidly spreading verrucous eruption 16 weeks after initiating upadacitinib. Assessment included dermoscopy, histopathological analysis of a shoulder lesion, and polymerase chain reaction-based microarray genotyping to identify the HPV subtype. Clinical examination revealed extensive disease, with numerous lobulated, hyperkeratotic papules and large confluent verrucous plaques involving the shoulders, chest and abdomen. Histopathology confirmed verruca vulgaris. HPV genotyping identified low-risk HPV-6, representing a notable genotype–site mismatch, as HPV-6 is classically a mucosal pathogen and rarely causes disseminated disease on keratinized skin. Given the rapid progression and disease burden, upadacitinib was discontinued and switched to lebrikizumab. Management included physical debulking of large plaques, targeted cryotherapy, topical salicylic acid and administration of the 9-valent HPV vaccine to reduce future acquisition risk and provide potential adjunctive therapeutic benefit. This case highlights that immunosuppression induced by modern targeted therapies can lead to atypical viral presentations, including the cutaneous manifestation of mucosal HPV strains. Proactive viral surveillance and a multimodal therapeutic approach may be required to manage severe or refractory viral disease in this population.