Palmoplantar Pustulosis at a Glance
- Chronic inflammatory disorder with sterile pustule formation.
- Affects only palms and soles.
- Disabling in severe cases.
- High rate of recurrence.
- Often resistant to treatment.
- Can be part of SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome.
Pustular eruptions of the palms and soles include palmoplantar pustulosis (PPP), acrodermatitis continua (Hallopeau disease), and infantile acropustulosis. The entities present with chronic and persistent eruptions of sterile, purulent vesicles.
A drug-induced rash clinically resembling PPP has been described in patients treated with tumor necrosis factor-α (TNF-α)-antagonists.
PPP is a chronic pustular dermatosis localized on the palms and soles only. High resistance to treatment and a high recurrence rate are characteristic. Histologically, it is characterized by intraepidermal vesicles filled with neutrophils.
Although many textbooks describe PPP along with psoriasis, it has an entity of its own.
The involvement of palms and soles has a great impact on life quality and the ability to work.
Epidemiology and Genetics
PPP has a worldwide distribution. It is a rare condition, but the exact incidence is not known. Females show a higher prevalence than males, with a ratio of approximately 3:1. Onset of the disease occurs mostly between the ages of 20 and 60 years; rarely, the condition occurs after the sixth decade of life, and in 10% of the patients the onset is before the age of 20 years.
HLA typing of patients with PPP reveals no increased frequency of any of the known psoriasis-linked alloantigens.1 In a direct comparison among chronic-plaque psoriasis, guttate psoriasis, and PPP, the three major candidate genes within the PSORS1 region [(1) HLA-Cw*6, (2) HCR*WWCC, and (3) CDSN*5] showed a high association to guttate and chronic plaque psoriasis, not, however, to PPP.2 Investigation of the apolipoprotein E alleles e2, e3, and e4 in chronic plaque and guttate psoriasis as well as in PPP in acitretin responders and nonresponders showed that the frequency of the e4 allele was significantly higher in the psoriasis groups but not in PPP patients as compared to healthy controls.3 In chronic plaque psoriasis and psoriatic arthritis an association with TNF-α-238 and -308 promoter polymorphisms have been found; however, the association has not been found in PPP.4 Studies from Japan provide evidence for phenotypic and genetic heterogeneity of PPP according to its association/provocation with tonsillitis. In patients in whom PPP was not associated with tonsillitis, the phenotype frequency of the TNF-β2 allele of the TNF-β gene and of the allele B of the TNF-α gene was significantly higher as compared to controls.5
Genetic association studies in a Caucasian cohort revealed that genes encoding for cytokines of the IL-10 family, namely, IL-19, IL-20, and IL-24 show haplotypes conferring increased risk for PPP.6
These findings further substantiate the notion that PPP and ...