Background  Palmoplantar psoriasis is a difficult to treat variant of plaque psoriasis.

Objective  To study the safety and efficacy of infliximab in non-pustular palmoplantar psoriasis.

Methods  Patients with non-pustular palmoplantar psoriasis affecting at least 10% of their palms and soles and with a modified palmoplantar psoriasis area and severity index (m-PPPASI) of at least eight were recruited. Patients were randomized (1:1) to receive infliximab 5 mg/kg or placebo at weeks 0, 2 and 6. Patients initially randomized to placebo received infliximab at weeks 14, 16 and 20 whereas patients randomized to infliximab received additional infliximab infusions every 8 weeks until week 22.

Results  Twenty four (24) patients were randomized in this study. At week 14, 33.3% and 66.7% of patients treated with infliximab achieved m-PPPASI 75 and m-PPPASI 50 respectively compared to 8.3% for both m-PPPASI 75 (P = 0.317) and m-PPPASI 50 (P = 0.009) for patients randomized to placebo. A reduction of 50.3% in the mean surface area of palms and soles affected with psoriasis was seen at week 14 in patients randomized to infliximab as compared to an increase of 14.9% in patients randomized to placebo (P = 0.009).

Conclusions  This pilot study did not reach its primary endpoint of m-PPPASI 75 at week 14. However, infliximab was observed to be more efficacious than placebo in improving PPSA and with respect to the percentage of patients reaching m-PPPASI 50 at week 14. Larger and longer term studies are needed for severe patients to better assess the efficacy of infliximab in palmoplantar psoriasis.