Diagnosing palmoplantar pustulosis requires careful examination of the skin on the hands and feet, combined with tests that help rule out similar conditions and confirm the presence of this chronic inflammatory skin disease.

Introduction: When to Seek Diagnosis

If you notice unusual blisters, pustules, or scaly patches developing on the palms of your hands or soles of your feet, it’s important to see a doctor for proper evaluation. People who experience persistent skin changes on these areas, especially if accompanied by itching, burning sensations, or painful cracks, should seek medical attention^[1]. Early diagnosis can help you start appropriate treatment sooner and potentially prevent the condition from worsening.

You should consider scheduling an appointment with a healthcare provider if you develop tiny blisters filled with yellow or white fluid on your palms or soles, particularly if these blisters eventually turn brown and become scaly^[2]. The condition can severely impact your quality of life by making everyday activities like walking, holding objects, or using your hands difficult and painful. Don’t wait until the symptoms become unbearable—seeking medical evaluation when you first notice changes can lead to better management of the condition.

People who smoke or have a history of smoking should be especially vigilant about changes to the skin on their hands and feet, as smoking is strongly associated with palmoplantar pustulosis. Studies show that up to 95% of people with this condition are current or former smokers^[2]. Additionally, individuals who already have psoriasis elsewhere on their body, or those with family members who have psoriasis, may be at higher risk and should monitor their skin carefully.

How Doctors Diagnose Palmoplantar Pustulosis

Diagnosing palmoplantar pustulosis typically begins with a thorough medical history and physical examination. Your doctor will ask about your symptoms, including when they started, how they’ve changed over time, and whether anything makes them better or worse. They’ll also want to know about your smoking history, any medications you’re taking, and whether you have psoriasis or other autoimmune conditions^[1].

The most important part of the diagnostic process is a careful visual examination of your skin. In many cases, doctors can make the diagnosis simply by looking at the characteristic appearance of the affected areas^[2]. The distinctive pattern of pustules on the palms and soles, along with scaling, redness, and the typical locations where lesions appear, often provides enough information for an experienced dermatologist to identify the condition.

During the examination, your doctor will look for specific features that suggest palmoplantar pustulosis. These include pustules that are typically 1 to 10 millimeters in size, often mixed with yellow-brown spots and scaly, red plaques. The pustules commonly appear on the fleshy parts at the base of the thumb and little finger (called the thenar and hypothenar eminences) and in the central palm^[1]. On the feet, lesions tend to develop on the arch, the inner and outer borders, and the sides or back of the heel.

Skin Scraping and Swab Tests

Because fungal infections can produce symptoms that look remarkably similar to palmoplantar pustulosis, your doctor will often take a painless skin scraping to check for fungal organisms^[2]. This test is simple and quick—the doctor gently scrapes a small amount of skin from the affected area and sends it to a laboratory where it can be examined under a microscope or cultured to see if fungi are present. This test is crucial because the treatments for fungal infections and palmoplantar pustulosis are completely different.

In addition to checking for fungi, your doctor may also take a swab of the fluid inside the pustules to rule out bacterial infection^[2]. Although the pustules in palmoplantar pustulosis are sterile—meaning they don’t contain bacteria or other infectious organisms—this test helps confirm the diagnosis by showing that no infection is present. The swab is painless and involves touching a cotton-tipped applicator to the blister to collect a sample of the fluid.

Skin Biopsy

Sometimes, when the diagnosis isn’t clear from examination and simple tests, your doctor may recommend a skin biopsy. This procedure involves removing a small piece of skin so it can be examined under a microscope by a pathologist^[2]. The biopsy helps distinguish palmoplantar pustulosis from other similar-looking conditions and can confirm the diagnosis definitively.

During a skin biopsy, the doctor will first numb the area with a local anesthetic injection, so you won’t feel pain during the procedure itself. They then remove a small sample of skin from an affected area—usually just a few millimeters in size. After the sample is taken, the doctor will close the wound with stitches, which typically need to be removed after about a week^[2]. The area should heal with only a small scar.

The tissue sample is then sent to a laboratory where it’s processed and examined under a microscope. The pathologist looks for specific features that are characteristic of palmoplantar pustulosis, including the structure of the pustules, the types of inflammatory cells present, and changes in the skin layers. This detailed examination can help confirm the diagnosis and rule out other conditions that might look similar on the surface.

Distinguishing Palmoplantar Pustulosis from Similar Conditions

One of the challenges in diagnosing palmoplantar pustulosis is that several other conditions can cause similar symptoms on the hands and feet. Your doctor needs to carefully consider these alternative diagnoses to ensure you receive the correct treatment.

Fungal infections, particularly tinea pedis (athlete’s foot) and tinea manuum (hand fungus), can produce scaling, redness, and even pustules that resemble palmoplantar pustulosis. This is why the skin scraping test is so important—it definitively shows whether fungi are present^[2]. Unlike palmoplantar pustulosis, fungal infections respond well to antifungal medications.

Contact dermatitis, which occurs when skin reacts to something it touches, can also cause blistering and scaling on the hands and feet. This condition typically develops after exposure to irritants like harsh soaps, chemicals, or allergens such as nickel. The pattern of symptoms and their relationship to specific exposures help doctors distinguish contact dermatitis from palmoplantar pustulosis.

Dyshidrotic eczema is another condition that causes small blisters on the palms and soles, making it easy to confuse with palmoplantar pustulosis. However, the blisters in dyshidrotic eczema are usually clear rather than filled with pus, and the condition often responds to treatments that wouldn’t help palmoplantar pustulosis. The microscopic appearance of a biopsy sample can help distinguish between these conditions.

A related condition called acrodermatitis continua of Hallopeau affects the tips of the fingers and toes rather than the palms and soles. While it’s considered a variant of pustular psoriasis, its distinct location and pattern help doctors tell it apart from typical palmoplantar pustulosis^[1].

Additional Screening for Associated Conditions

Once palmoplantar pustulosis is diagnosed, your doctor may recommend screening for other health conditions that are often found alongside it. This comprehensive approach helps ensure all aspects of your health are properly addressed.

Many patients with palmoplantar pustulosis have a diagnosis of psoriasis vulgaris (the most common form of psoriasis) affecting other parts of their body, and some develop psoriatic arthritis, which causes joint inflammation^[1]. Your doctor will examine your skin thoroughly to look for psoriasis plaques elsewhere on your body and ask about joint pain or stiffness that might suggest arthritis.

Research has found associations between palmoplantar pustulosis and several other medical conditions. People with this skin condition have higher rates of type 2 diabetes and chronic obstructive pulmonary disease (COPD)^[1]. Your doctor may recommend blood tests to check your blood sugar levels and assess your overall metabolic health. If you’re a current or former smoker, lung function tests might be appropriate to evaluate for COPD.

Other conditions that appear more frequently in people with palmoplantar pustulosis include thyroid disorders, coeliac disease (an immune reaction to gluten), high blood pressure, high cholesterol, and metabolic syndrome^[1]. Depending on your symptoms and medical history, your doctor might order thyroid function tests, screening for coeliac disease, or tests to evaluate your cardiovascular risk factors.

Nail Examination

Your doctor will also carefully examine your fingernails and toenails as part of the diagnostic process. Palmoplantar pustulosis can affect one or more nails, causing them to become thicker, discolored, or develop ridges and small dents called pitting^[2]. In some cases, affected nails may separate from the nail bed underneath. These nail changes can help support the diagnosis and provide additional evidence that you have palmoplantar pustulosis rather than another skin condition.