Palmoplantar Pustulosis: Clinical Characteristics and Variability in Therapeutic Approaches

To the Editor,

Palmoplantar pustulosis (PPP) is a rare immune-mediated skin disorder characterized by chronic relapsing eruptions of neutrophil-filled pustules on the palms and soles. ¹ The estimated global prevalence of PPP ranges from 0.01% to 0.12% and is over twice as common in females than males. ² To date, there is a paucity of studies describing the demographic characteristics and clinical management of patients with PPP and this study aims to address this knowledge gap.

Research ethics board approval was obtained. A retrospective chart review was conducted of patients aged 18 years or older, diagnosed with PPP between January 1st, 2011 and December 31^st, 2020 at a tertiary care center located in Ottawa, Canada. Patients were excluded if they had a previous diagnosis of generalized pustular psoriasis, acute generalized exanthematous pustulosis, synovitis–acne–pustulosis–hyperostosis–osteitis or acrodematitis continua of Hallopeau. Data were extracted by authors HO-YL, MW, DC, and BM. Data analysis was performed using Stata SE version 16.1.

Of the 66 patients included, the majority (79%) were female and the average age at diagnosis was 56 years (Supplemental Table 1). Over half of patients (55%) were previous or current smokers. Approximately half of patients (49%) had a history or presence of plaque psoriasis at the time of diagnosis. The most prescribed treatments at time of diagnosis were clobetasol (38%), phototherapy (36%), and acitretin (15%). A small proportion of patients (17%) were treated with biologics (Supplemental Table 2), and among these patients, secukinumab was the most commonly prescribed (36%) followed by ustekinumab (27%), and infliximab (9%), adalimumab (9%), etanercept (9%), and certolizumab (9%). Less than one-third of patients (18%) achieved remission during the study period, with PPP lesions resolving within an average of 6 years. Among those who achieved remission, a wide range of treatment regimens were used, including topical therapy (17%), methotrexate/cyclosporine (25%), biologics (17%), and acitretin/alitretinoin with biologics (17%).

While the exact pathogenesis of PPP remains unclear, it is likely multifactorial. Inflammatory states may induce PPP, with reported triggers including smoking, stress, focal infections such as tonsillitis and dental infections, and dental metal allergies. ² Gene mutations have also been associated with PPP, including IL36RN, CARD14, and AP1S3, suggesting a potential genetic predisposition. ^{1 -4} Although standardized treatment guidelines are lacking, topical corticosteroids and vitamin D3 are most commonly used, with the occasional addition of systemic treatments such as methotrexate, cyclosporin, alitretinoin, and isotretinoin. ⁵ For PPP with concurrent focal infection, antibiotics or surgical interventions may provide added benefit. ⁵ Finally, biologics including anti-IL-23 antibodies have been increasingly prescribed for PPP. ⁵

In conclusion, this retrospective study highlights the demographic distribution of patients with PPP and the significant variability in therapeutic approaches used in clinical practice. Further research is required to better elucidate the clinical characteristics of this patient population and the efficacy of various therapies. Ultimately, broadening our understanding of this rare disease will inform treatment algorithms and improve clinical outcomes for patients with PPP.

Supplemental Material

Table S1 - Supplemental material for Palmoplantar Pustulosis: Clinical Characteristics and Variability in Therapeutic Approaches

Supplemental material, Table S1, for Palmoplantar Pustulosis: Clinical Characteristics and Variability in Therapeutic Approaches by Emily Seale, Heidi Oi-Yee Li, Miranda Waugh, Daniela Cino, Barbara Marzario and Mark G. Kirchhof in Journal of Cutaneous Medicine and Surgery