Pustular Psoriasis
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Direct answer
Pustular psoriasis is a group of sterile pustular variants of psoriasis, ranging from localised disease on the palms and soles to a life-threatening generalised eruption. The generalised form, von Zumbusch type, presents with fever, erythema and widespread sterile pustules, and it is a dermatological emergency. Palmoplantar pustulosis and acrodermatitis continua of Hallopeau are the localised variants, and treatment priorities depend on the extent of disease and on any systemic features.
What you must remember
- Generalised pustular psoriasis: von Zumbusch type, with sterile pustules on erythematous skin, fever, leucocytosis and systemic upset.
- Hypocalcaemia: low calcium can complicate generalised disease and can cause tetany, so levels must be checked and corrected.
- Genetic link: mutations in the IL36RN gene are found in a subset of patients, pointing to the interleukin-36 pathway.
- Palmoplantar pustulosis: recurrent sterile pustules on the palms and soles that evolve into brown scaly patches, with smoking as the strongest recognised risk factor.
- Acrodermatitis continua of Hallopeau: sterile pustules of the distal fingers and toes and nail beds, causing progressive nail dystrophy and sometimes bone changes at the distal phalanges.
- Triggers: infection, pregnancy, abrupt withdrawal of systemic or potent topical steroids, and drugs such as lithium, beta-blockers and some antimalarials.
- Management: generalised disease needs admission, fluid and electrolyte support and infection screening, with acitretin, methotrexate or ciclosporin and biologics as systemic options.
Pustular variants at a glance
The variants differ in extent and in urgency, so the table sets out where each one occurs and what must be done first.
| Variant | Site | Key feature | Priority management |
|---|---|---|---|
| Generalised (von Zumbusch) | Whole body | Fever, sterile pustules, systemic upset | Admit; fluid, electrolyte and calcium care; acitretin, methotrexate, ciclosporin or biologics |
| Palmoplantar pustulosis | Palms and soles | Recurrent sterile pustules turning brown and scaly | Stop smoking; potent topical steroids, PUVA or acitretin |
| Acrodermatitis continua | Distal digits and nail beds | Pustules with nail dystrophy and bone change | Topical steroids; systemic retinoid or methotrexate if refractory |
Generalised disease needs immediate hospital care, whereas palmoplantar and nail variants are usually managed as outpatients with topical and systemic options. Sterile pustules should still be checked for infection, with cultures sent before escalating treatment, because infection is a common trigger and can look similar.
Admission for generalised disease also allows close monitoring of fluid balance, temperature, albumin and calcium, with early dermatology review. Patients should be told that flares can recur, and avoiding known precipitating drugs and stopping smoking are the most practical preventive steps.
Where the exam tries to catch you
Pustular psoriasis questions test the variants, the steroid trap and the monitoring of calcium.
- Trap: treating generalised pustular psoriasis as a bacterial skin infection with antibiotics alone Correct: the pustules are sterile, so antibiotics do not treat the disease, although infection is excluded and treated when present.
- Trap: giving systemic steroids to control a flare Correct: steroids can precipitate or worsen generalised pustular psoriasis, and their withdrawal is a classic trigger.
- Trap: linking palmoplantar pustulosis with fungal infection Correct: it is sterile and strongly linked to smoking, and fungal tests should be negative.
- Trap: missing hypocalcaemia in generalised disease Correct: low calcium can cause tetany and must be checked and corrected.
Frequently asked questions
What is von Zumbusch pustular psoriasis?
Von Zumbusch pustular psoriasis is the generalised form of pustular psoriasis, with widespread sterile pustules on erythematous skin, fever and systemic upset. It is a dermatological emergency that needs hospital care. Triggers include steroid withdrawal, infection and certain drugs.
Which genetic change is linked to generalised pustular psoriasis?
Mutations in the IL36RN gene are linked to generalised pustular psoriasis in a subset of patients. These mutations affect the interleukin-36 pathway. Genetic testing is not routine in most clinical settings.
What is palmoplantar pustulosis and what is its main risk factor?
Palmoplantar pustulosis is a chronic, localised pustular eruption of the palms and soles, and smoking is its strongest recognised risk factor. The sterile pustules evolve into brown scaly patches and recur in crops. Stopping smoking is a key part of management.
What is acrodermatitis continua of Hallopeau?
Acrodermatitis continua of Hallopeau is a pustular psoriasis variant affecting the distal fingers and toes, with sterile pustules in the nail bed. It causes progressive nail dystrophy and can be associated with bone changes at the distal phalanges. Topical steroids are used first, with systemic agents for refractory disease.