Long-Standing Remission After Tildrakizumab Treatment in a Case of Refractory Type I Pityriasis Rubra Pilaris in a Breast Cancer Patient.

Pityriasis rubra pilaris (PRP) is a rare chronic inflammatory skin disease characterised by follicular keratotic papules and perifollicular erythema coalescing into orange-red scaly plaques, and palmoplantar keratoderma. Characteristic islands of sparing are usually observed. A standardised therapeutic approach is lacking owing to the infrequent occurrence of this disease. However, anti-interleukin (IL)-17 and anti-IL-23 therapies have recently emerged as effective therapies in patients affected by PRP, with improvements in severity scores, change in severity of erythema, scaling, and thickness of lesions. Here, we report a 43-year old, female breast cancer who developed severe refractory PRP, which greatly impacted her quality of life. The patient experienced a marked improvement after treatment with tildrakizumab. Treatment was stopped after one year, and the three-year follow-up did not show relapse. In conclusion, 52- week treatment with tildrakizumab, an IL-23 antagonist, proved to be a favourable treatment option for PRP, leading to good patient adherence, improvement in quality of life, and long-term follow-up without relapse.