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PubMed This is a summary of 13 peer-reviewed journal articles Updated
Dermatology · Palmoplantar Pustulosis

The Biology and Misdiagnosis of Palmoplantar Pustulosis

At a Glance

Palmoplantar Pustulosis (PPP) is an autoinflammatory condition causing sterile, non-contagious pustules on the hands and feet. It is frequently misdiagnosed as dyshidrotic eczema or fungal infections. PPP flare-ups are driven by immune system signals and are linked to smoking and hidden infections.

Many patients with Palmoplantar Pustulosis (PPP) spend years searching for the correct diagnosis. Because the hands and feet can react to many different irritants, PPP is frequently mistaken for common conditions like eczema or a fungal infection. Understanding the unique biology of PPP and how it differs from its “look-alikes” is the first step toward getting the right treatment.

Why the Immune System Attacks

PPP is an autoinflammatory condition, meaning your immune system’s “alarm system” is stuck in the “on” position [1]. Unlike an infection where the body attacks a germ, in PPP, the body creates an intense inflammatory response for no apparent reason [2].

  • The “Alarm” Signals: The primary drivers of this inflammation are chemical messengers called interleukins, specifically IL-36 and IL-1. These act like a chemical siren, calling for reinforcements [3][4].
  • The First Responders: In response to these signals, the body recruits neutrophils—a type of white blood cell—to the skin of your palms and soles [5][2].
  • The Result: These neutrophils cluster together to form the white or yellow pustules you see on your skin [6]. Because these pustules are caused by your immune system and not a germ, they are sterile, meaning they are not contagious [2].

Avoiding Misdiagnosis

PPP is famous for “mimicking” other skin problems. To ensure an accurate diagnosis, doctors must distinguish it from three main look-alikes:

Condition Primary Difference from PPP
Dyshidrotic Eczema Involves vesicles (tiny, clear, fluid-filled blisters) rather than yellow pustules. Under a microscope, eczema shows spongiosis (fluid buildup between skin cells) and lymphocytes, rather than the heavy neutrophil clusters found in PPP [6][7].
Tinea (Fungal Infection) Caused by a fungus (like athlete’s foot). While it can look similar, a fungal infection will show organisms under a microscope or in a lab culture, whereas PPP pustules are always sterile [5][8].
Plaque Psoriasis Classic psoriasis usually features thick, silvery scales on elbows or knees. While related, PPP specifically targets the palms and soles and is more likely to be triggered by smoking or focal infections [9][10].

The Global Debate: Is it Psoriasis?

If you read about your condition online, you may see it called “Palmoplantar Pustular Psoriasis.” However, there is a major international debate among doctors about whether this is accurate [11][5].

  • The Western View: Many doctors in the U.S. and Europe view PPP as a variant or “subtype” of psoriasis because the two conditions share some genetic markers and can occur together in the same person [12][13].
  • The Japanese View: In Japan, where the disease is more common, dermatologists largely classify PPP as a distinct disease [11][9]. They argue that the biology of PPP is unique because it is so strongly linked to external triggers like smoking and infections in the tonsils or teeth [9][10].

Understanding which camp your doctor falls into can help you understand your treatment plan. For example, if your doctor views it as a distinct entity, they may be more likely to screen you for hidden infections. You can learn more about how to bring this up with your doctor in Building Your Care Team and Daily Management.

Common questions in this guide

Is palmoplantar pustulosis contagious?
No, palmoplantar pustulosis is not contagious. The white or yellow pustules on your hands and feet are sterile, meaning they are caused by your immune system's inflammatory response and not by a bacterial or fungal infection.
How can my doctor tell the difference between PPP and eczema?
While both can affect the hands and feet, dyshidrotic eczema typically features tiny, clear, fluid-filled blisters. In contrast, PPP causes white or yellow pustules. A skin biopsy can also differentiate them by looking for dense clusters of neutrophils, which are found in PPP.
Is palmoplantar pustulosis considered a type of psoriasis?
There is ongoing medical debate about this. Many doctors in the U.S. and Europe view PPP as a variant of psoriasis due to shared genetics. However, doctors in Japan often classify it as a distinct disease because its triggers, like smoking and focal infections, are unique.
Can a dental or tonsil infection cause pustules on my hands and feet?
Yes, hidden focal infections in the teeth or tonsils can act as an immune trigger for palmoplantar pustulosis. If your doctor views PPP as a distinct condition driven by these external factors, they may screen you for underlying infections.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Do you view my condition as a distinct disease or as a variant of psoriasis, and how does that view change my treatment plan?
  2. 2.Could you explain if my biopsy showed 'neutrophilic' involvement, and how that helps rule out dyshidrotic eczema?
  3. 3.Has a KOH test or fungal culture been performed to rule out a fungal infection (tinea)?
  4. 4.Given the role of the IL-36 and IL-17 pathways in my condition, are there specific biologics that target these 'alarm' signals?
  5. 5.Is it possible that my pustules are a 'sterile' reaction to an infection elsewhere in my body, like my tonsils or teeth?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (13)
  1. 1

    Pustular psoriasis as an autoinflammatory keratinization disease (AiKD): Genetic predisposing factors and promising therapeutic targets.

    Akiyama M

    Journal of dermatological science 2022; (105(1)):11-17 doi:10.1016/j.jdermsci.2021.11.009.

    PMID: 34973880
  2. 2

    Interventions for chronic palmoplantar pustulosis: abridged Cochrane systematic review and GRADE assessments.

    Obeid G, Do G, Kirby L, et al.

    The British journal of dermatology 2021; (184(6)):1023-1032 doi:10.1111/bjd.19560.

    PMID: 32961599
  3. 3

    Anakinra for palmoplantar pustulosis: results from a randomized, double-blind, multicentre, two-staged, adaptive placebo-controlled trial (APRICOT).

    Cro S, Cornelius VR, Pink AE, et al.

    The British journal of dermatology 2021; doi:10.1111/bjd.20653.

    PMID: 34411292
  4. 4

    Exploring the Role of IL-36 Cytokines as a New Target in Psoriatic Disease.

    Iznardo H, Puig L

    International journal of molecular sciences 2021; (22(9)) doi:10.3390/ijms22094344.

    PMID: 33919434
  5. 5

    Successful Treatment of Palmoplantar Pustulosis With Apremilast.

    Dorgham N, Crasto D, Skopit S

    Journal of drugs in dermatology : JDD 2021; (20(11)):1255-1256 doi:10.36849/jdd.6098.

    PMID: 34784120
  6. 6

    Comments about the comparative bulk RNA sequencing between palmoplantar pustulosis and dyshidrotic palmoplantar eczema.

    Yatsuzuka K, Muto J, Murakami M

    F1000Research 2024; (13()):1494 doi:10.12688/f1000research.159565.1.

    PMID: 39810849
  7. 7

    Immunohistochemical evaluation of keratins and involucrin in differentiating between palmoplantar pustulosis and pompholyx.

    Oh DY, Kim SJ, Jang YJ, et al.

    International journal of dermatology 2024; (63(6)):780-786 doi:10.1111/ijd.17018.

    PMID: 38214207
  8. 8

    Pompholyx vesicles contain small clusters of cells with high levels of hyaluronate resembling the pustulovesicles of palmoplantar pustulosis.

    Murakami M, Muto J, Masuda-Kuroki K, et al.

    The British journal of dermatology 2019; (181(6)):1325-1327 doi:10.1111/bjd.18261.

    PMID: 31254390
  9. 9

    Treatment Guidance for Palmoplantar Pustulosis 2022.

    , Terui T, Kobayashi S, et al.

    The Journal of dermatology 2026; (53(7)):e510-e566 doi:10.1111/1346-8138.70246.

    PMID: 42252553
  10. 10

    Retrospective analysis of the clinical response of palmoplantar pustulosis after dental infection control and dental metal removal.

    Kouno M, Nishiyama A, Minabe M, et al.

    The Journal of dermatology 2017; (44(6)):695-698 doi:10.1111/1346-8138.13751.

    PMID: 28150339
  11. 11

    Guselkumab for the Treatment of Palmoplantar Pustulosis: A Japanese Perspective.

    Yamamoto T

    Clinical pharmacology : advances and applications 2021; (13()):135-143 doi:10.2147/CPAA.S266223.

    PMID: 34188558
  12. 12

    What do we know about palmoplantar pustulosis?

    Misiak-Galazka M, Wolska H, Rudnicka L

    Journal of the European Academy of Dermatology and Venereology : JEADV 2017; (31(1)):38-44 doi:10.1111/jdv.13846.

    PMID: 27521275
  13. 13

    Is palmoplantar pustulosis simply a variant of psoriasis or a distinct entity?

    Misiak-Galazka M, Wolska H, Rudnicka L

    Journal of the European Academy of Dermatology and Venereology : JEADV 2017; (31(7)):e342-e343 doi:10.1111/jdv.14136.

    PMID: 28107577

This page is for informational purposes only and does not replace professional medical advice. Always consult your dermatologist for an accurate diagnosis and treatment plan for your skin condition.

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