Management of palmoplantar pustulosis

Palmoplantar pustulosis or chronic palmoplantar pustular psoriasis (PPP) is an uncommon but disabling and recalcitrant pustular dermatosis affecting the palms and soles. Its onset is strongly linked to cigarette smoking and once it is established it tends to progress gradually over years or decades. Its relationship to psoriasis is disputed. Treatment is unsatisfactory and many different therapeutic manoeuvres have been advocated. We have performed a Cochrane systematic review of PPP in order to assess the evidence for efficacy of treatments for PPP. Randomized controlled trials (RCTs) of interventions for PPP were sought by interrogating the Cochrane Controlled Trials Register, Medline and Embase for the terms (PALM* or PLANT* or SOLE* or BACTERID) and (PUSTUL* or PSORIA*). Additional searches were undertaken by cross‐checking with two databases of psoriasis trials collated in our department and by the European Epidermo‐Epidemiology Network (EDEN). We found 23 RCTs that met our inclusion criteria. These comprised eight trials of systemic retinoid monotherapy [six vs. placebo, one vs. psoralen photochemotherapy (PUVA), one comparing two retinoids]; four trials of PUVA or retinoid‐PUVA (two PUVA vs. placebo, two PUVA vs. PUVA plus systemic retinoid); two trials each in which cyclosporin, hydroxyurea, a tetracycline or colchicine was compared with placebo; one trial of Grenz ray therapy vs. placebo; and two trials of topical corticosteroids under hydrocolloid gel occlusion compared either with steroid alone or with additional PUVA therapy. Many of the studies were of short duration with small numbers of participants. Outcome measures used varied considerably between studies. The following interventions were shown to be significantly better than placebo in reducing disease severity scores in PPP: etretinate, liarazole, PUVA using oral psoralen, low dose cyclosporin, Grenz ray therapy, tetracycline antibiotics. Acitretin was of equal efficacy to etretinate. Overall however, few patients achieved good or excellent results. Potent topical corticosteroids were shown to be more effective if used under occlusion. The addition of PUVA to such therapy was of no extra benefit. No RCT of methotrexate therapy was found but evidence from one open study suggests that it is of limited efficacy. The following interventions were also of no or minimal benefit: PUVA using topical psoralen, hydroxyurea, colchicine. The best results were achieved with systemic retinoid therapy both on its own (40% good or excellent response) and in conjunction with oral PUVA (68% clearance) when it was more effective than topical or oral PUVA alone. The value of systemic retinoids for long‐term therapy is, however, diminished by their side‐effects. The ideal therapy for PPP remains elusive.