Introduction
Palmo-plantar Pustulosis (PPP) is a chronic, relapsing dermatosis characterised by localised areas of inflamed skin which are evenly studded with whitish-yellow on the palms and soles of the feet. Despite it affecting a relatively small surface area of the skin, owing to the location it can have a significant impact on the patient’s quality of life [1]. Moreover, population studies have shown how it arises with other conditions. This blog explores the known associations of PPP.
What is Palmo-plantar Pustulosis?
Palmo-plantar Pustulosis (PPP) is a chronic, relapsing dermatosis characterised by localised areas of inflamed skin that are evenly studded with whitish-yellow on the palms and soles of the feet. The condition may be unilateral or symmetrical and accompanied by localised hyperkeratosis and painful fissuring. Pustules gradually resolve to leave a brown scale.
Also known as Pustulosis Palmaris et Plantaris, the condition typically affects adults in middle age (40-60 years), around 0.01 – 0.05% of the population have the condition [2]. The condition predominantly affects females, with studies suggesting between 65% and 94% of cases occur in females [3, 4], around an 8:1 female-to-male ratio [5].
PPP is probably not psoriasis
For many years the condition was considered to be a variant of psoriasis. This has been covered in an earlier blog but essentially PPP is most likely to be a separate disease showing different characteristics to psoriasis, for example – failure to respond to psoriasis treatments and no association with arthritis [6]. However, it is not uncommon for the two conditions to co-exist [7].
An autoimmune disease
Over the years there has been much discussion about the disease – particularly its potential association with smoking [8, 9]. A 1985 case control study showed a smoking rate of 80% amongst PPP patients versus just 36% of controls [10]. Following this, there have been a number of studies examining the epidemiology and its associated conditions. The hypothesis that PPP is an autoimmune (AI) disease can be strengthened when looking at patients with the disease. One feature of AI disease is that sufferers generally are at risk of having more than one AI condition [11]. I have covered a review of the pathology of PPP in an earlier publication which can be downloaded here
Associated conditions
Previous surveys of patients with PPP have uncovered a range of co-existing conditions (see table below):
Another study from Korea compared co-morbidities of patients with PPP, with those with psoriasis and pompholyx. The cohort of 37 399 PPP patients was impressive. The comparison demonstrated that patients with PPP were more likely to also have diabetes (type 1 and type 2), vitiligo, Graves disease (autoimmune hyperthyroidism), psoriasis, and Crohns disease [13].
Discussion
PPP is an uncommon but often frustrating condition. Pustulation on the soles and palms can seriously affect a patient’s quality of life, with cases being prolonged and resistant to most conventional forms of treatment. However, in recent years there have been developments in this area with the introduction of biological agents targeting specific inflammatory molecules which have shown promise (more on that in a future blog).
Aside from the difficulties of the condition itself, it’s important to be aware of the co-morbidities particularly the cardio-vascular effects of hypertension and hyperlipidaemia which seem to affect more than a third of patients with PPP. Practitioners need to remain vigilant and undertake vascular assessments and blood pressure monitoring when required. Careful assessment of any patient presenting with the condition should be undertaken which may uncover previous undiagnosed conditions such as thyroid disease which can manifest in the lower limb and foot in a number of ways.
Please note: A patient information leaflet is available from the British Association of Dermatologists website
References
1. Trattner, H., et al., Quality of life and comorbidities in palmoplantar pustulosis – a cross-sectional study on 102 patients. Journal of the European Academy of Dermatology and Venereology, 2017. 31(10): p. 1681-1685.
2. Misiak-Galazka, M., J. Zozula, and L. Rudnicka, Palmoplantar Pustulosis: Recent Advances in Etiopathogenesis and Emerging Treatments. Am J Clin Dermatol, 2020. 21(3): p. 355-370.
3. Kubota, K., et al., Epidemiology of psoriasis and palmoplantar pustulosis: a nationwide study using the Japanese national claims database. BMJ Open, 2015. 5(1).
4. Michaelsson, G., G. Kristjansson, I. Pihl Lundin, and E. Hagforsen, Palmoplantar pustulosis and gluten sensitivity: a study of serum antibodies against gliadin and tissue transglutaminase, the duodenal mucosa and effects of gluten-free diet. British Journal of Dermatology, 2007. 156(4): p. 659-666.
5. Misiak-Galazka, M., et al., General Characteristics and Comorbidities in Patients with Palmoplantar Pustulosis. Acta Dermatovenerol Croat, 2018. 26(2): p. 109-118.
6. Yamamoto, T., Similarity and difference between palmoplantar pustulosis and pustular psoriasis. The Journal of Dermatology, 2021. 48(6): p. 750-760.
7. Haidari, W. and S.R. Feldman, Rates of psoriasis in patients with palmoplantar pustulosis. 2019. 181(5): p. 887-888.
8. Kobayashi, K., et al., Cigarette Smoke Underlies the Pathogenesis of Palmoplantar Pustulosis via an IL-17A–Induced Production of IL-36γ in Tonsillar Epithelial Cells. Journal of Investigative Dermatology, 2021. 141(6): p. 1533-1541.e4.
9. Sarıkaya Solak, S., et al., Clinical characteristics, quality of life and risk factors for severity in palmoplantar pustulosis: a cross-sectional, multicentre study of 263 patients. Clin Exp Dermatol, 2022. 47(1): p. 63-71.
10. O’Doherty, C.J. and C. MacIntyre, Palmoplantar pustulosis and smoking. Br Med J (Clin Res Ed), 1985. 291(6499): p. 861-4.
11. Somers, E.C., S.L. Thomas, L. Smeeth, and A.J. Hall, Are Individuals With an Autoimmune Disease at Higher Risk of a Second Autoimmune Disorder? American Journal of Epidemiology, 2009. 169(6): p. 749-755.
12. Becher, G., L. Jamieson, and J. Leman, Palmoplantar pustulosis – a retrospective review of comorbid conditions. Journal of the European Academy of Dermatology and Venereology, 2014. 29(9): p. 2-3.
13. Kim, D.H., J.Y. Lee, S.I. Cho, and S.J. Jo, Risks of Comorbidities in Patients With Palmoplantar Pustulosis vs Patients With Psoriasis Vulgaris or Pompholyx in Korea. JAMA Dermatology, 2022.
