Despite, the fact that palmoplantar pustulosis is still widely known by this name, it is currently regarded as a disease distinct from psoriasis. The real cause is still unknown. Septic foci have been blamed, but their removal may not cure eruptions. A case series of de novo occurrence of palmoplantar pustulosis induced by tumor necrosis factor-alpha antagonist therapy has been reported. It has been shown that stress may be related to exacerbation of palmoplantar pustulosis. Some authors suggest that palmoplantar pustulosis is an autoimmune disease. In sera of patients with palmoplantar pustulosis circulating autoantibodies against nicotinic acetylcholine receptors were detected. The differences between palmoplantar pustulosis and pustular palmoplantar psoriasis are numerous. Genetic studies have failed to find any link between palmoplantar pustulosis and major genetic susceptibility locus for psoriasis vulgaris. Most patients with palmoplantar pustulosis have no evidence of psoriasis elsewhere. Histologically, it closely resembles psoriasis. However, accumulation of neutrophils just beneath the corneal layer, finding known as Munro’s microabscess, and dilation of capillaries in the papillary dermis are lacking. Approximately 90% of patients are women. A significantly higher prevalence of smokers was found in the group with palmoplantar pustulosis than in the normal population and a particularly strong association was confirmed between smoking and pustular lesions in patients with psoriasis, OR=5.3 (2.1-13.0). Nevertheless, according to a recent review from the Cochrane Library, there is no evidence that smoking cessation improves the condition once it has developed.
Topical corticosteroids under occlusion are the first-line therapy. Prolonged therapy is needed on a second or third-day basis, in order to sustain the obtained effects. Oral retinoids in combination with oral PUVA are the best second-line therapy. No difference in the efficacy between etretinate and acitretin was found. The disadvantage of systemic retinoid therapy is its teratogenicity. Oral PUVA is effective and the response is enhanced by combination with retinoids. There is an established increased efficacy of a combination of retinoids with PUVA therapy over each treatment modallity when used alone. Liarozole may be an effective and well-tolerated therapy, but side effects are like in retinoids. The advantage over acitretin is that raised levels of retinoic acid fall to normal within a few days after cessation of therapy. Significant improvement, but no complete clearance, occurs in most patients treated with low dose cyclosporine. Before starting the treatment, it is necessary to consider: patient’s individual factors, since many patients have already received some previous treatment; specific treatment factors such as formulation, way of administration, dose, different drug combinations; regimens and periods of treatment; site of involvement, due to differences between hands and feet in the probability of response to treatment.