Generalised Pustular Psoriasis

Synonyms: acute generalised pustular psoriasis of von Zumbusch, pustular psoriasis von Zumbusch variant.

This is a generalised, explosive eruptive form of psoriasis accompanied by fever and toxicity. Acute erythema is seen with a diffuse distribution of multiple sterile pustules over the body, concentrated in the flexures, genital regions and fingertips.

Generalised Pustular Psoriasis needs to be distinguished from a localised form of pustular psoriasis known as Palmoplantar Pustulosis (PPP).

Generalised pustular psoriasis is uncommon - precise prevalence figures for the UK are not available. Prevalence is 7 per 1 million in Japan.¹ The average age of those affected is 50 but the range is wide.
Polymorphonuclear leukocyte chemotaxis appears to be rather more pronounced in this condition than in ordinary psoriasis but it is unclear if this is the cause or the result of the variant. There is some evidence that it may predispose to the disease.²

• The skin becomes very red and tender.
• Symptoms include headache, fever, chills, arthralgia, malaise, anorexia and nausea.
• The patient often looks anxious. There is a fast respiratory rate, tachycardia and pyrexia suggesting a toxic state. The tongue is dry and cracked.
• Clusters of pustules appear within hours. They are superficial, 2 to 3mm in diameter and may appear in a generalised pattern.
• The flexural and anogenital regions are most commonly affected. Facial lesions are less common.
• Pustules may occur on the tongue and under the nails, causing dysphagia and loss of nails respectively.
• Within the next 24 hours, the pustules coalesce, dry and desquamate in sheets. The underlying skin that appears is smooth and erythematous but new crops of pustules may appear.
• These episodes of pustule formation may occur for days to weeks, leaving the patient uncomfortable and exhausted.
• 2 or 3 months later a telogen effluvium type of hair loss may develop.
• As the pustules remit, most systemic symptoms ebb too but the patient can be left with erythroderma or with residual lesions of ordinary psoriasis.

• Systemic steroid withdrawal
• Drugs: salicylates, iodine, lithium, phenylbutazone, oxyphenbutazone, trazodone, penicillin, hydroxychloroquine, calcipotriol, interferon-alpha and recombinant interferon-beta injection.
• Topical medications causing irritation: coal tar, anthralin, steroids under occlusive dressing and zinc pyrithione in shampoos
• Infections
• Sunlight or phototherapy
• Cholestatic jaundice
• Hypocalcaemia

No cause is identified in many patients.

• Drug eruptions
• Septicaemia

• FBC shows a marked rise in neutrophils whilst lymphocytes are reduced. ESR is elevated. The white count may rise to 25 to 40 x 10⁹/l,with a marked drop in the lymphocyte count. If this is noted and treatment can be started before the clinical disease, it may abort it.³
• Serum globulin is raised and albumin is low.
• Calcium and zinc levels are reduced.
• If there is a marked reduction in blood volume, renal function parameters will be abnormal with elevated creatinine and if renal tubular necrosis occurs, there will be casts in the urine.
• Cultures of pustules and blood cultures are negative.

Admit to hospital urgently as this is a life threatening condition.

• Adequate hydration must be maintained. This may require the intravenous route.
• Bed rest is recommended and if a substantial amount of skin is involved, loss of heat may be a problem.
• Bland topical compresses and saline or oatmeal baths assist in soothing and debriding affected areas. For children, this is often all that is required.
• Specific medications include:
  • oral retinoids, usually acitretin
  • methotrexate
  • ciclosporin
  • 6-thioguanine
  • hydroxycarbamide (hydroxyurea)
• The new biological therapies such as alefacept, etanercept and infliximab have been used with success at times.
• Topical calcineurin inhibitors such as tacrolimus and pimecrolimus have been effective in some cases of pustular psoriasis limited to the palms and soles.
• PUVA cannot normally be tolerated in the early stage, except perhaps in children who tend to experience a milder disease. Once the patient is stable, usually after several days of acitretin, then PUVA may be commenced. Results are good.³

The very new treatments have not been used extensively and the literature is still rather limited. This is partly due to the rarity of the disease. Therapeutic guidelines based on a scoring system have been suggested.⁴

• Secondary bacterial infection of the skin may occur.
• Hair loss with telogen effluvium is possible.
• If the subungual areas are involved, the nails will be lost.
• Hypoalbuminemia may result from loss of plasma protein into tissues.
• Hypocalcaemia.
• Reduced circulating volume may cause renal tubular necrosis.
• Poor circulation and general toxicity may cause liver damage.
• Malabsorption and malnutrition
• Death from cardio-respiratory failure is rare and usually in untreated patients. It trends to occur in the acute erythrodermic phase. Occasionally acute respiratory distress syndrome may complicate generalised pustular psoriasis.

• Older patients with the von Zumbusch-type variant have a poor prognosis.
• Children tend to have a good prognosis unless there is secondary infection.
• If the pustular psoriasis was preceded by ordinary chronic psoriasis, the prognosis is better than if it was preceded by an atypical form.