Pustular Psoriasis: Types, Triggers, and Treatment Options

What Is Pustular Psoriasis?

Pustular psoriasis looks nothing like the typical plaque psoriasis that most people picture when they hear the word “psoriasis.” Instead of silvery scales on raised red patches, pustular psoriasis produces white or yellowish, pus-filled bumps (pustules) surrounded by red, tender skin. These pustules are sterile, meaning they are not caused by an infection. Rather, they are filled with neutrophils, a type of white blood cell that has been called to the skin in massive numbers by an overactive inflammatory response [1].

Pustular psoriasis accounts for less than 5% of all psoriasis cases, making it relatively rare [2]. But what it lacks in prevalence, it makes up for in severity. Some forms of pustular psoriasis can become medical emergencies requiring hospitalization.

Types of Pustular Psoriasis

Generalized Pustular Psoriasis (GPP) / Von Zumbusch Type

This is the most severe and dangerous form. Generalized pustular psoriasis (GPP) presents with widespread, painful pustules that can cover large areas of the body. It typically begins with a sudden onset of fiery red skin, followed within hours by crops of tiny pustules that merge into larger “lakes of pus” [3]. Systemic symptoms accompany the skin findings and can include:

• High fever (often exceeding 39 degrees Celsius or 102 degrees Fahrenheit)
• Rapid heart rate
• Severe fatigue and malaise
• Joint pain
• Loss of appetite and weight loss

GPP can lead to serious complications including secondary bacterial infections, sepsis, hepatic abnormalities, hypocalcemia, acute kidney injury, and respiratory distress [4]. The mortality rate for untreated GPP has historically been reported between 2 and 16%, making it a true dermatologic emergency [5].

Recent genetic research has identified mutations in the IL36RN gene in many GPP patients. This gene encodes the IL-36 receptor antagonist, a natural anti-inflammatory protein. When this protein is deficient or dysfunctional, the IL-36 signaling pathway becomes hyperactive, driving the massive neutrophil infiltration that defines the disease [6].

Palmoplantar Pustulosis (PPP)

Palmoplantar pustulosis affects the palms of the hands and soles of the feet. Yellow-brown pustules appear on a background of red, thickened skin, often in a symmetrical pattern. The pustules go through cycles: they start white or yellow, darken to brown as they dry out, then desquamate (peel off), and new ones form [7].

PPP is the most common form of pustular psoriasis and is chronic and relapsing. It has a strong association with smoking, with up to 90% of PPP patients being current or former smokers [8]. Whether PPP is truly a subtype of psoriasis or a distinct disease is debated in the dermatology community. Some evidence suggests it has a partially different genetic basis and pathophysiology compared to plaque psoriasis [7].

PPP is particularly disabling because it affects the hands and feet. Walking, gripping objects, exercising, and performing manual work can all become painful. Quality-of-life scores in PPP patients are often worse than those in patients with moderate plaque psoriasis [8].

Acrodermatitis Continua of Hallopeau (ACH)

This rare variant affects the tips of the fingers and toes, particularly around and under the nails. Pustules form on the distal digits and can destroy the nail apparatus over time, eventually causing permanent nail loss in severe cases [9]. ACH often starts after local trauma to a finger or toe and can be resistant to many treatments. Some experts consider it the localized form of GPP, as it can occasionally generalize into full-blown GPP [1].

What Triggers Pustular Psoriasis Flares

Understanding triggers is essential for prevention. The most well-documented triggers include:

Medication Withdrawal

The most notorious trigger for GPP is the abrupt withdrawal of systemic corticosteroids. This is one of the primary reasons why systemic steroids are generally avoided in psoriasis management. When a patient with psoriasis (even stable plaque psoriasis) has been taking oral steroids and stops them suddenly, the rebound inflammatory response can trigger a widespread pustular flare [10]. Other medications associated with triggering pustular psoriasis include:

• Rapid tapering of cyclosporine
• Lithium
• Terbinafine
• Hydroxychloroquine
• Iodide-containing medications

Infections

Upper respiratory infections and other viral or bacterial illnesses can precipitate flares of GPP. The systemic immune activation from an infection can tip the balance in a patient who is already prone to pustular psoriasis [4].

Pregnancy

A specific form of GPP can occur during pregnancy, previously known as “impetigo herpetiformis.” It typically presents in the third trimester and can pose risks to both mother and fetus, including placental insufficiency and preterm delivery [11]. This form usually resolves after delivery but may recur in subsequent pregnancies.

Other Triggers

• Emotional stress
• Hypocalcemia (low calcium levels)
• Excessive UV exposure (sunburn)
• Local irritants (for PPP)
• Smoking (strongly associated with PPP)

Emergency Considerations for Generalized Pustular Psoriasis

If you or someone you know develops a widespread pustular rash with fever, seek medical attention immediately. GPP requires urgent evaluation and often hospitalization. In the emergency setting, the priorities are:

• Stabilization: Fluid resuscitation, electrolyte correction (especially calcium), and management of fever.
• Skin care: Gentle care of the fragile, eroded skin to prevent secondary infection. Wet wraps and bland emollients are used.
• Monitoring: Blood work to check for leukocytosis, elevated inflammatory markers (CRP, ESR), liver function abnormalities, kidney function, and electrolyte imbalances [4].
• Identifying triggers: Reviewing recent medication changes, infections, and other potential precipitants.
• Initiating treatment: Starting targeted therapy as quickly as possible to control the flare.

Treatment Options for Pustular Psoriasis

Spesolimab: A Breakthrough for GPP

Spesolimab (Spevigo) was approved by the FDA in 2022 as the first treatment specifically indicated for generalized pustular psoriasis flares. It is a monoclonal antibody that blocks the IL-36 receptor, directly targeting the key inflammatory pathway in GPP [12]. In the Effisayil 1 clinical trial, 54% of patients treated with a single intravenous dose of spesolimab achieved a Generalized Pustular Psoriasis Physician Global Assessment (GPPGA) pustulation subscore of 0 (complete pustule clearance) at one week, compared to 6% with placebo [12]. This represented a major advance for a disease that previously had no targeted therapy.

Acitretin

This oral retinoid has been a mainstay of GPP treatment for decades. Acitretin reduces pustule formation and skin inflammation, typically at doses of 25 to 50 mg daily. It can be effective for both acute flares and maintenance therapy [13]. However, it is teratogenic (causes severe birth defects) and must not be used during pregnancy or for at least 3 years before conception in women of childbearing age.

Cyclosporine

Cyclosporine can produce rapid improvement in GPP and is often used as a bridge therapy during acute flares. It works by suppressing T-cell activation and cytokine production. The main limitations are nephrotoxicity and hypertension with long-term use, so it is typically used for short courses [4].

Methotrexate

Methotrexate can be effective for pustular psoriasis but works more slowly than cyclosporine. It is sometimes used for longer-term maintenance after the acute flare is controlled [13].

Biologic Therapies

Beyond spesolimab, several biologics used for plaque psoriasis have shown efficacy in pustular psoriasis, though most are used off-label for this indication:

• IL-17 inhibitors (secukinumab, ixekizumab): Case series and small studies report benefit in GPP and PPP [14].
• TNF-alpha inhibitors (infliximab): Infliximab, given intravenously, can produce rapid improvement in GPP and is sometimes used as rescue therapy in acute flares.
• IL-23 inhibitors (guselkumab, risankizumab): Guselkumab has been approved for GPP in Japan and has shown promising results in clinical trials [14].

Treating Palmoplantar Pustulosis

PPP is notoriously difficult to treat. Options include:

• Potent topical corticosteroids (often under occlusion)
• Topical PUVA (psoralen plus UVA phototherapy) for the palms and soles
• Acitretin (first-line systemic option for many dermatologists)
• Smoking cessation (critical, as smoking perpetuates the disease)
• Biologics, though response rates in PPP tend to be lower than in plaque psoriasis [8]

How Pustular Psoriasis Differs from Plaque Psoriasis

While pustular and plaque psoriasis are related, there are important differences:

• Appearance: Plaque psoriasis features thick, scaly plaques. Pustular psoriasis features pus-filled blisters on red, tender skin.
• Systemic symptoms: Plaque psoriasis is typically a skin-only disease (aside from joint involvement). GPP can cause fever, organ dysfunction, and life-threatening complications.
• Genetics: GPP has specific genetic associations (IL36RN mutations) that differ from the primary genetic risk factors for plaque psoriasis [6].
• Overlap: Many GPP patients also have a history of plaque psoriasis, but GPP can occur without any prior plaque disease. About 30 to 40% of GPP patients have no history of plaque psoriasis [3].
• Treatment response: Pustular and plaque psoriasis do not always respond to the same treatments. The IL-36 pathway is uniquely important in pustular psoriasis.

Living with Pustular Psoriasis

A diagnosis of pustular psoriasis (particularly GPP) can be frightening. Here are some practical considerations:

• Build a medical team: Work with a dermatologist experienced in managing severe psoriasis. GPP management often benefits from a multidisciplinary approach.
• Know your triggers: Keep a detailed log of flares and what preceded them. Avoid systemic corticosteroids unless absolutely necessary and medically supervised.
• Have a flare plan: Discuss with your dermatologist what to do at the first sign of a flare. Early intervention can prevent escalation.
• If you smoke, quit: This is especially critical for PPP. Smoking cessation is one of the few modifiable factors shown to influence disease course [8].
• Seek support: The National Psoriasis Foundation and other patient advocacy organizations offer resources and community connections for people with rare forms of psoriasis.

Related Reading

• Psoriasis: Complete Guide
• Psoriasis Treatment Options
• Psoriasis Biologics Guide
• Guttate Psoriasis

References

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