Palmoplantar Psoriasis: A Complete, Research-Based Guide

Palmoplantar psoriasis affects two of the most functionally important, constantly used parts of the body: the palms and the soles. Despite covering a relatively small body surface area, it consistently ranks among the most disabling and difficult-to-treat forms of psoriatic disease.

This guide brings together current dermatology research on what palmoplantar psoriasis actually is, how it differs from a closely related but genetically distinct condition, and what the evidence shows about treating it effectively.

What Is Palmoplantar Psoriasis?

Palmoplantar psoriasis refers to psoriasis specifically localized to the palms of the hands and soles of the feet. As introduced in our types-of-psoriasis guide, it can present in more than one clinical pattern, and understanding which pattern is present directly shapes treatment decisions.

Two Distinct Clinical Patterns

Dermatology literature recognizes a genuine split within palmoplantar disease, and this distinction runs throughout this entire guide. Palmoplantar psoriasis and palmoplantar pustulosis are chronic skin diseases with a large impact on patient quality of life, and while related, current research treats them as distinct clinical entities with important differences in epidemiology, genetics, histopathology, and pathogenesis.

The first, more straightforward pattern is hyperkeratotic palmoplantar psoriasis, which looks like classic plaque psoriasis, well-demarcated, red, scaly plaques, simply relocated to the palms and soles. The second is palmoplantar pustulosis (PPP), a genuinely different-looking condition involving sterile, pus-filled pustules rather than typical scaly plaques.

Palmoplantar Psoriasis vs. Palmoplantar Pustulosis: Same Disease or Not?

This is one of the more actively debated classification questions in modern dermatology, and it’s worth understanding clearly rather than glossing over. The answer genuinely affects how a patient’s condition should be evaluated and treated.

The Case for PPP Being a Separate Disease

A growing body of research argues palmoplantar pustulosis shouldn’t be classified as psoriasis at all. Although initially thought to be a variant of psoriasis, PPP is now regarded by many researchers as a separate entity rather than a disease on the psoriasis spectrum, and despite the fact that some patients have psoriasiform plaques on other parts of the body, these lesions are not considered typical psoriatic plaques.

The genetic evidence supporting this separation is fairly compelling. PPP is not associated with the major psoriasis susceptibility locus PSORS1 or HLA-C:06:02, suggesting a genetically distinct entity from plaque psoriasis, according to DermNet’s clinical reference. Instead, genetic mutations involving IL36RN, CARD14, ATG16L1, and AP1S3 may be associated with PPP specifically.

Why the Eccrine Sweat Gland Matters So Much

The anatomical explanation for why PPP concentrates specifically on palms and soles centers on a structure unique to this skin. Eccrine sweat glands and the acrosyringium, the point where the sweat duct opens onto the skin surface, play the central role in the pathogenesis of PPP, and this is precisely why the condition doesn’t appear anywhere else on the body with the same character.

It is believed that the primary target of inflammation in PPP is the acrosyringium, the eccrine sweat gland apparatus, according to a structured review of the condition’s burden. This is fundamentally different from how plaque psoriasis develops elsewhere on the body, where the hair follicle and interfollicular epidermis, not sweat gland structures, are the primary site of pathology.

The Case for Keeping Them Together

Despite this genetic and anatomical evidence, the classification debate isn’t fully settled, and there are practical reasons to discuss both conditions together. Both entities can respond to similar treatments and have a similar impact on quality of life, and many patients and clinical trials continue to use overlapping terminology and outcome measures for both.

Because of this overlap, this guide covers both conditions, while being clear about which research applies specifically to which pattern.

How Common Is Palmoplantar Psoriasis?

Precise prevalence figures for palmoplantar disease specifically are harder to pin down than for psoriasis generally, partly because of the classification debate described above. Still, several consistent demographic patterns emerge across the available research.

Who Develops Palmoplantar Pustulosis?

Unlike plaque psoriasis, which affects men and women in roughly similar numbers, PPP shows a pronounced gender skew. PPP is a disease with strong female predominance, a pattern confirmed across multiple independent studies in different countries.

Age of onset also follows a fairly consistent pattern. PPP most commonly develops in mid-adulthood, and unlike plaque psoriasis, family history of psoriasis is present in only a minority of cases, reinforcing the genetic distinction discussed above.

What Causes Palmoplantar Psoriasis and PPP?

The underlying biology differs meaningfully between the hyperkeratotic and pustular patterns of palmoplantar disease, echoing the broader classification question discussed above.

The Overwhelming Role of Smoking

If there’s one environmental factor that dominates palmoplantar pustulosis research more than any other, it’s tobacco smoking. As covered in depth in our “Smoking and Psoriasis” guide, this association is among the strongest of any environmental risk factor identified anywhere in dermatology.

The majority of patients with palmoplantar pustulosis are cigarette smokers, with 70% to 90% of patients being current or former smokers, and smoking is also a disease-aggravating factor. The proposed mechanism connects directly back to the sweat gland pathology described above.

It is thought that in individuals with PPP, nicotine is secreted into eccrine glands to promote inflammation and alter the local immune response, and activation of nicotinic acetylcholine receptors by nicotine specifically, rather than by the body’s own acetylcholine, may lead to the accumulation of eosinophils and neutrophils and consequently to pustule formation. Nicotine appears to affect nearby keratinocytes as well, causing increased keratosis of the excretory ducts, contributing to the scaling seen alongside pustules.

The Innate and Adaptive Immune Response

Beyond smoking as a trigger, the immune biology driving PPP involves several of the same inflammatory pathways discussed in our “Inflammation and Psoriasis” guide, applied to this specific anatomical site. In PPP, both the innate and adaptive immune systems are activated, and acrosyringeal expression of IL-17 has been demonstrated, indicating that the eccrine sweat gland is an active, immune-competent component of the skin barrier, not merely a passive structure being attacked from outside.

Specific cytokines have been directly measured in affected tissue. Interleukin-8, IL-36 gamma, and IL-36 receptor antagonist all play important roles in the pathogenesis of pustular psoriasis, with researchers specifically studying their relationship to acrosyringeal changes and pustule formation in PPP tissue samples.

Dental and Focal Infections

An unusual but recurring finding in PPP research involves a genuinely unexpected trigger: infections centered in the mouth and throat. Dental infection has been documented as a triggering factor in palmoplantar pustulosis, a pattern that echoes the tonsillar mechanism discussed in our “Smoking and Psoriasis” guide’s coverage of PPP.

This connection has led some clinicians to specifically screen for and treat dental or tonsillar infections in patients with treatment-resistant PPP, though this remains a more specialized, second-line consideration rather than a first-line diagnostic step for every patient.

Mechanical Trauma and Friction

Beyond smoking and infection, physical factors specific to the hands and feet contribute to disease activity. Environmental factors such as manual or repetitive trauma, irritants, and friction have been associated with palmoplantar pustulosis, echoing the Koebner phenomenon discussed in our “What Causes Psoriasis?” guide, applied to skin that faces near-constant mechanical stress from gripping and walking.

Medication Triggers

Certain medications are specifically documented to trigger or worsen palmoplantar disease. Drug-induced cases have been particularly associated with TNF-alpha inhibitors, an important and somewhat ironic finding, since TNF-alpha inhibitors are themselves used to treat plaque psoriasis elsewhere on the body.

Both plaque psoriasis and palmoplantar pustulosis may be precipitated by lithium, and infliximab specifically can worsen the disease, potentially related to the role of TNF-alpha in normal eccrine sweat duct function. Anyone developing new palm or sole pustules while on a biologic medication for another condition should raise this possibility with their prescribing physician promptly.

Comorbidities Linked to Palmoplantar Disease

Beyond the skin itself, palmoplantar pustulosis in particular has been linked to a distinctive comorbidity profile, somewhat different from the metabolic and cardiovascular pattern seen in plaque psoriasis and discussed in our pillar guide.

Thyroid Disease

Thyroid dysfunction shows up repeatedly across PPP research, more prominently than in plaque psoriasis generally. There is an increased incidence of autoantibodies to thyroid antigens in palmoplantar pustulosis patients, and multiple independent studies have documented thyroid disease as a recurring comorbidity.

Figures vary somewhat between study populations. One study found thyroid disease in 8% of PPP patients, alongside gluten sensitivity in 1% and type 2 diabetes in 10%, while other cohorts have reported thyroid involvement at similar or somewhat higher rates.

Metabolic Comorbidities

Metabolic disease patterns in PPP show interesting variation across different populations studied. Rates of diabetes, hypertension, and hyperlipidemia reported in an Austrian cohort were 18.6%, 38.0%, and 32.4% respectively, notably higher than in a Japanese cohort, where the same conditions were found at 7.7% to 9.3%, 17.3% to 18.3%, and 21.7% to 22.4%. This geographic variation suggests both genetic and environmental or lifestyle factors likely contribute to comorbidity risk.

Diabetes specifically has shown a particularly strong, statistically robust association in controlled research. One study found diabetes mellitus was significantly more frequent in PPP patients than in age- and gender-matched healthy controls, with an adjusted odds ratio of 8.7, a substantial difference that shouldn’t be dismissed as coincidental.

Joint and Bone Involvement

PPP carries its own distinctive relationship with joint and bone disease, separate from the nail-enthesis connection discussed in our nail psoriasis pillar guide. The prevalence of psoriatic arthritis in PPP patients has been reported at 8.6% to 26% across different study populations.

A particularly distinctive bone-related finding is specific enough to warrant its own diagnostic category. Sternocostoclavicular ossification, an unusual bone change affecting the joint where the collarbone meets the breastbone, occurs in about 10% of palmoplantar pustulosis cases, and this finding, alongside pustulosis, forms part of a recognized cluster of conditions called SAPHO syndrome, mentioned in our pillar guide’s discussion of unique psoriasis presentations.

Nail Involvement

Nail changes are genuinely common in PPP, though estimates vary by study population. Nail involvement in PPP ranges from 30% to 76% across different studies, with a Seoul-based study finding a 66.3% prevalence and a direct correlation between nail changes and overall disease severity, with onycholysis and crumbling as the predominant findings.

Regional data suggests somewhat lower, though still substantial, rates elsewhere. In Northern European populations, nail involvement has been reported in roughly one-third of PPP cases, with subungual pustulation as a distinguishing feature. This connects directly to the broader nail psoriasis biology discussed in our dedicated nail psoriasis pillar guide.

Clinical Presentation

Hyperkeratotic Palmoplantar Psoriasis

This pattern looks like a localized version of classic plaque psoriasis: well-demarcated, red, thickened, scaly plaques confined to the palms and soles. Painful cracking and fissuring is common, given the mechanical stress these areas face daily, a topic covered in more practical depth in our “Camel Foot Appearance in Psoriasis” guide’s discussion of plantar cracking and fissure care.