Ustekinumab: An effective agent for refractory pityriasis rubra pilaris? Three cases with a literature review

Author(s) De Brito M.; Coulson I.H.; Dhawan G.; Alassaf J.; Bewley A.
Source British Journal of Dermatology; May 2021; vol. 184 (no. 5)
Pityriasis rubra pilaris (PRP) is a rare, papulosquamous dermatosis, which may progress to erythroderma. We present three cases of refractory type 1 PRP with complete response to ustekinumab, an anti-interleukin (IL)-12/IL-23 biologic. A 57-year-old woman presented with a pruritic psoriasiform eruption that responded incompletely to retinoid or methotrexate. It became widespread, with spared islands and palmoplantar keratoderma. Skin biopsy suggested type 1 PRP. Despite acitretin with ciclosporin, she developed erythroderma, which required hospital admission, and was refractory to azathioprine, systemic steroids and erythromycin. After her first injection of ustekinumab, her skin improved and she remains clear on ustekinumab. A 61-year-old man presented with a widespread scaling eruption diagnosed as type 1 PRP. Methotrexate was contraindicated owing to his alcohol intake. Acitretin was ineffective, with a significantly impaired quality of life [Dermatology Life Quality Index (DLQI) 16]. He became erythrodermic. After his first injection of ustekinumab, his erythema reduced by 50%. By the fourth injection, his skin was clear. He stopped ustekinumab after 18 months, and has remained clear since. A 64-year-old woman presented with type 1 PRP, with erythroderma, nail changes, orange keratoderma and spared islands over the trunk. She required admission and, despite acitretin, methotrexate, ciclosporin and infliximab, there was no improvement. Four weeks after her first ustekinumab injection, her skin was almost clear. Her DLQI reduced from 25 to 5. She stopped ustekinumab after 6 months and has remained clear since. Reports of ustekinumab in PRP are limited to case reports/case series, where 14/15 patients sustained a significant response at 4-8 weeks (Naidoo A, Sibbald C, Fleming et al. Use of biologics in pityriasis rubra pilaris refractory to first-line systemic therapy: a systematic review. J Cutan Med Surg 2020; 24: 77-8). These cases suggest that ustekinumab may be effective in refractory type 1 PRP.

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