What is pustular psoriasis?

Pustular psoriasis is a chronic autoimmune skin disorder. It is characterised by the presence of pus-filled blisters on the surface of the skin.¹ To understand pustular psoriasis, it is essential to understand psoriasis itself. Psoriasis is a common skin disorder that accelerates the life cycle of skin cells, causing cells to build up rapidly on the skin’s surface. This leads to red, scaly patches that are often itchy and uncomfortable.² Pustular psoriasis is an uncommon form of this condition, which can be further categorised into different types, each presenting unique symptoms.

Read on to learn more about pustular psoriasis.

Understanding psoriasis

Psoriasis is a lifelong autoimmune skin disease which is caused by both genetic and environmental factors.² Genetics play a significant role, with a family history of psoriasis increasing the likelihood of its development.³ Environmental factors can also trigger or worsen psoriasis symptoms.² When a person has psoriasis, their immune system is overactive, which causes excessive production of skin cells.² This overproduction of skin cells results in the formation of thickened, red, and scaly patches on the surface of the skin.² Additionally, inflammation caused by psoriasis can affect other parts of the body such as the joints.

The symptoms and how they present are diverse and vary from person to person. The most common form is known as plaque psoriasis which usually presents as raised, red patches of skin covered with silvery or white scales.³ These patches are often itchy and/or painful and can appear anywhere on the body but are typically found on the elbows, knees, scalp, and lower back.³ Other forms of psoriasis, including guttate, inverse, pustular, and erythrodermic exhibit different characteristics and patterns of skin presentation.³ Individuals with psoriasis might also experience changes in their nails such as pitting or separation of the nail from the nail bed.²

Diagnosing psoriasis is done via examination by a healthcare professional, commonly a dermatologist. The diagnosis is usually based on the visual appearance of the skin and nails.⁴ In some cases, a sample of skin is tested in the lab by a histologist to confirm and rule out other skin conditions that may be confused with psoriasis.⁴ During the examination, the appearance and spread of skin lesions is taken into consideration as well as other symptoms such as itching or pain. The patient's medical and family history is also looked at.⁴ Dermatologists will also assess the impact of the condition on the patient's quality of life to deliver a tailored management plan.

Understanding pustular psoriasis

Pustular psoriasis is a distinctive form of psoriasis. The exact cause of pustular psoriasis is unknown, but genetic predisposition and environmental factors contribute to its onset.¹ Triggers such as stress, infections, and certain medications can induce or worsen episodes of pustular psoriasis. It is characterised by the formation of pus-filled blisters on the skin called pustules. They are often surrounded by red, inflamed skin and can spread all over the body.^1,5 The pustules can burst which can leave skin feeling raw and tender. New pustules may begin forming on the damaged ones, leading to a vicious cycle.⁵ Pustular psoriasis can be further categorised based on the clinical presentation and location of pustules, known as generalised or localised pustular psoriasis.

Types of pustular psoriasis

Pustular psoriasis can manifest in various forms. Localised pustular psoriasis usually affects the hands and feet whilst generalised pustular psoriasis covers most of the body.

• Generalised pustular psoriasis (GPP):^5,6 This type of pustular psoriasis is widespread, with pustules forming across large areas of the body. This is often accompanied by fever, chills, dehydration, and the general feeling of being ill. This type of psoriasis must be treated immediately with medication, or it can become life-threatening from a sudden drop in blood pressure. GPP usually affects adults, but children may develop it too if they have genetic mutations that predispose them to the condition
• Impetigo herpetiformis:^5,6 This is a rare type of generalised pustular psoriasis which occurs during pregnancy, commonly in the third trimester. It begins with pustules that develop on the patient’s inner thighs and groin, which can also develop inside the mouth and under the nails. As the condition develops, the pustules spread over the body. If left untreated, this condition can become life-threatening for the patient and the baby. Impetigo herpetiformis usually clears up when the person is no longer pregnant but may flare up if they become pregnant again
• Palmoplantar pustulosis (PPP):^5,6 This is a localised form of pustular psoriasis which can last for a considerable period of time when it flares up. For individuals with PPP, pustules form specifically on the palms of their hands and the soles of their feet. As the pustules burst and dry up, the affected skin darkens and can scale or crack
• Acrodermatitis continua of Hallopeau (ACH):^5,6 This localised form of pustular psoriasis targets the fingertips and toes causing painful pustules and changes to the nails. In many cases, individuals end up losing their nails or parts of their nails

Evaluation and treatment of pustular psoriasis

Individuals with suspected pustular psoriasis must be clinically evaluated as some types can be life-threatening. Often, a complete blood count will be taken to evaluate the number of white blood cells to rule out infection and other conditions that may present with similar symptoms, such as acute generalised exanthematous pustulosis.^1,7 A dermatologist will conduct a physical examination of the patient and take a complete medical history including a family history of psoriasis and related conditions.⁶ When the diagnosis of pustular psoriasis has been confirmed, treatment options will vary based on the clinical presentation.

• Topical corticosteroids:^5,7 Corticosteroids are commonly prescribed to treat pustular psoriasis. Corticosteroids are anti-inflammatory medications that work by suppressing the immune response. In the context of pustular psoriasis, they help alleviate inflammation, redness, and itching associated with the condition. Topical corticosteroids are often the first line of treatment for pustular psoriasis, especially in milder cases. In more severe cases or when pustular psoriasis affects larger areas of the body, healthcare providers may prescribe systemic corticosteroids. These are taken orally or administered through injections and are reserved for short-term use due to potential long-term side effects
• Retinoids:^5,7 retinoids, derived from vitamin A, influence cell growth and differentiation. In pustular psoriasis, they help regulate skin cell turnover and reduce inflammation. Topical retinoids may be prescribed to target specific areas of pustular psoriasis. Systemic retinoids, taken orally, are sometimes recommended for more widespread pustular psoriasis. These medications are reserved for severe cases and are closely monitored due to potential side effects
• Medication and biologics:^5,7 In more severe cases, immunosuppressants such as methotrexate may be prescribed to treat the condition at its roots. Biologics, which are treatments made using living organismscan also be prescribed to decrease inflammation. Some examples of Biologics are monoclonal antibody therapies like Spesolimab and Infliximab
• Lifestyle changes:^5,8 To address triggers that can lead to flare-ups, healthcare professionals may recommend a number of lifestyle changes. Stress management techniques, adopting a balanced diet, and maintaining proper skin care routines are essential in managing any form of psoriasis. Moisturising the skin regularly helps alleviate dryness and reduce the risk of flare-ups from skin irritation
• Therapeutic interventions:^5,7 therapeutic interventions, ranging from phototherapy to ultraviolet B (UVB) light exposure, are used to manage pustular psoriasis. PUVA therapy, involving a combination of psoralen (a medication) and light therapy with ultraviolet A (UVA) light, is another option

Management approaches for pustular psoriasis are highly individualised. What works for one person may differ for another person, emphasising the importance of open communication between patients and healthcare professionals to tailor a treatment plan.

Summary

In summary, pustular psoriasis is a form of psoriasis which is marked by pus-filled blisters and influenced by genetic predisposition and environmental triggers. Pustular psoriasis is an uncommon yet distinctive form within the spectrum of psoriasis. Pustules, surrounded by red and inflamed skin, present a unique challenge, potentially forming a vicious cycle if left untreated. Understanding its unique characteristics and distinctions into various types is paramount. The diverse forms, including Generalised Pustular Psoriasis (GPP), Impetigo Herpetiformis, Palmoplantar Pustulosis (PPP), and Acrodermatitis Continua of Hallopeau (ACH), underscore the complexity of the condition. Each type of pustular psoriasis demands specific attention due to its distinct characteristics, potential complications, and, in some cases, life-threatening implications. Due to the life-threatening symptoms, clinical evaluation becomes essential for individuals with suspected pustular psoriasis. Diagnostic measures, including a complete blood count and dermatological examination, guide the confirmation of the diagnosis. Treatment options, ranging from medications and topical treatments to lifestyle changes and therapeutic interventions, highlight the individualised nature of pustular psoriasis management.