Palmoplantar pustulosis triggering factors
Palmoplantar pustulosis (PPP) causes recurrent sterile pustules, typically surrounded by red, scaly skin that may crack and develop fissures. While the exact cause remains unclear, both internal factors (such as genetics and immune system mechanisms) and external triggers contribute to the development and worsening of PPP. Understanding the triggers of palmoplantar pustulosis is key to managing symptoms and reducing flare-ups.
What causes palmoplantar pustulosis?
The precise cause of PPP is not fully understood and may vary from person to person. The condition is believed to result from a combination of genetic predisposition, immune system dysregulation and environmental factors. Palmoplantar pustulosis is part of a broader group of pustular dermatoses and shares some similarities with psoriasis, although it has distinct features, particularly in its localization and biological pathways.
Studies have identified variations in certain immune-related genes that are more common in individuals with PPP. These genes are involved in inflammatory signalling, particularly cytokines like interleukins, which regulate immune responses in the skin. Not all people with PPP carry these genetic variations, but those with a genetic predisposition may have skin tissue that is more sensitive to external stresses. Immune system activity also plays a major role, with inflammatory cells accumulating in the affected skin and promoting pustule formation. Environmental factors often interact with this immune response to trigger symptoms of palmoplantar pustulosis.
Main triggers of palmoplantar pustulosis
Several environmental and lifestyle factors are associated with the onset or exacerbation of symptoms. These triggers may not cause PPP in everyone, but they can provoke or worsen the condition in those with underlying susceptibility.
Smoking and tobacco exposure
Smoking is the most consistently reported trigger for PPP. A large proportion of people with PPP are either current or former smokers, and research shows that smoking significantly increases the risk of developing the condition. Nicotine and other components in tobacco smoke can interact with immune cells in the skin, triggering inflammation.
Trauma and mechanical irritation
Repeated physical stress on the palms and soles, such as friction, pressure or microtrauma, can trigger PPP in predisposed individuals. The skin on these areas is constantly exposed to mechanical forces, and such irritation can activate inflammatory pathways, leading to pustule formation. This helps explain why flare-ups are common in people who work with their hands or spend long hours standing or walking.
Infections
Infections, particularly of the upper respiratory tract (such as tonsillitis or sinusitis) or dental infections, have been linked to the onset or flare-ups of PPP. These infections can trigger immune responses, increasing inflammation at vulnerable skin sites.
Contact allergens and irritants
Some people with PPP are sensitive to certain metals or chemicals. Allergies to metals like nickel and chromium are associated with flare-ups in some individuals. Similarly, skin irritants such as harsh soaps, detergents, and cleaning products can weaken the skin’s barrier, making it more prone to inflammation.
Medications
Certain medications have been linked to the onset or worsening of PPP. Drugs that affect immune pathways, such as tumour necrosis factor (TNF) alpha inhibitors used for inflammatory diseases, can paradoxically trigger pustular eruptions in some patients. While these medications are used to treat conditions like rheumatoid arthritis or plaque psoriasis, they may sometimes worsen PPP through complex immune system effects.
Stress and hormonal influences
Psychological stress and hormonal fluctuations can influence immune function and inflammatory responses. Many people with PPP report that stress often precedes flare-ups. Hormonal changes, particularly those related to body weight and metabolism (such as obesity or metabolic syndrome), can also impact the severity and frequency of flare-ups.
Weather and environmental conditions
Environmental factors such as heat and sweating can irritate the skin on the palms and soles, promoting inflammation and triggering PPP lesions. Avoiding prolonged exposure to hot, humid environments may help reduce flare-ups for some individuals
References
- National Organization for Rare Disorders. Palmoplantar pustulosis [Internet]. Available from: https://rarediseases.org/rare-diseases/palmoplantar-pustulosis/
- DynaMed. Palmoplantar pustulosis overview [Internet]. Available from: https://www.dynamedex.com/condition/palmoplantar-pustulosis#GUID-264E576F-5B5E-4278-9053-9E41D05AE96A
- DermNet NZ. Palmoplantar pustulosis causes and triggers [Internet]. Available from: https://dermnetnz.org/topics/palmoplantar-pustulosis/