Pustular psoriasis: types, warning signs and emergency care in the UK

Psoriasis is a long-term inflammatory skin condition in which the skin makes new cells far faster than usual. In the pustular forms, small blisters filled with pus develop on red skin. NHS inform stresses that in generalised pustular psoriasis the pus is made up of white blood cells and is not a sign of infection, so antibiotics do not treat it.

The main forms are generalised pustular psoriasis (von Zumbusch psoriasis), palmoplantar pustular psoriasis (also called palmoplantar pustulosis) and acropustulosis. They differ widely in seriousness, which is why the first question in any assessment is whether the person is systemically unwell.

NHS inform describes three main patterns. Generalised pustular psoriasis causes pustules on a wide area of skin that develop very quickly and may reappear every few days or weeks in cycles; at the start of a cycle there may be fever, chills, weight loss and fatigue. Palmoplantar pustular psoriasis causes pustules on the palms of the hands and the soles of the feet that gradually develop into circular brown, scaly spots, which then peel off. Acropustulosis causes pustules on the fingers and toes that burst, leaving bright red areas that may ooze or become scaly and can lead to painful changes in the shape of the nails.

PCDS describes generalised pustular psoriasis as presenting with widespread pustules on a background of red and tender skin. In most patients no cause is found, but some have a preceding history of chronic plaque psoriasis, and triggers include withdrawal of systemic corticosteroids or very potent topical steroids in a person with known psoriasis, drugs such as lithium and salicylates, and pregnancy.

The NHS says to call 999 or go to A&E if you have psoriasis and your skin quickly turns red and you develop white, pus-filled bumps that join together, if patches on your feet turn yellow-brown and are filled with pus, or if your fingers and toes have red, scaly pus-filled bumps on the tips. It notes that redness may be harder to see on brown or black skin.

These can be signs of a more serious condition or an infection, and the NHS lists other symptoms that may appear with them: a fast heartbeat, a high temperature, or feeling hot, cold or shivery. It advises not driving yourself and bringing the medicines you take. PCDS describes clinical progression: within hours, 1 to 2 mm pustules appear, especially in the flexures and genitalia, and after a day or so they merge into lakes of pus, which dry and peel to leave a glazed surface on which new crops may appear.

• Skin that quickly turns red with white pus-filled bumps that join together.

• Yellow-brown, pus-filled patches on the feet.

• Red, scaly, pus-filled bumps on the tips of fingers and toes.

• Fast heartbeat, high temperature or feeling hot, cold or shivery.

Diagnosis is mainly clinical. NHS inform says a GP will examine the skin, a biopsy is sometimes needed, and a dermatologist may be involved if symptoms are severe. For the generalised form, NICE emphasises recognising systemic upset such as fever and malaise, which it says are common in unstable forms of psoriasis such as erythroderma or generalised pustular psoriasis.

For generalised pustular psoriasis, PCDS says patients are often very unwell and need admission, and the most appropriate action is to phone the on-call dermatologist. NICE advises immediate referral for same-day specialist assessment and treatment. Specialist treatment follows hospital protocols and may include systemic and biological agents, which NHS inform lists as methotrexate, ciclosporin, acitretin and biological injections for severe psoriasis.

Palmoplantar pustulosis is a chronic problem and is hard to treat. PCDS says effective treatment can be difficult: potent topical steroids such as 0.1% betamethasone or clobetasol ointment may be used at night under occlusion, and those who fail to respond should be referred to dermatology for hand or foot phototherapy or systemic therapy. NICE says to consider psoralen with local ultraviolet A irradiation (PUVA) for palmoplantar pustulosis, discussing the associated skin cancer risk.

PCDS says palmoplantar pustulosis has a strong link with cigarette smoking, although it adds that stopping smoking does not often lead to an improvement. About 25% of patients have a background of chronic plaque psoriasis, and it mainly presents in people over 50, in women more than men.

Generalised pustular psoriasis can recur, so the aim after a flare is to find and avoid triggers, such as abrupt steroid withdrawal, and to keep long-term treatment under a dermatology team. The localised forms are not usually dangerous but they can be painful, interfere with walking and hand use, and are persistent.

The NHS says living with psoriasis can be difficult, and that a mental health specialist referral may be offered if it affects mental health. Support and information are available from patient organisations such as Psoriasis UK, which the NHS names.

Suspected generalised pustular psoriasis is an emergency and is managed through urgent NHS routes, with admission under dermatology where needed. This is not something to wait for a routine or private appointment for.

For the chronic hand and foot form, either NHS dermatology or a private consultant can advise on topical treatment, phototherapy and systemic options. Ask which treatments have been tried and what the next step would be.