Generalised pustular psoriasis
What is generalised pustular psoriasis?
Generalised pustular psoriasis is a rare form of psoriasis, which presents as widespread pustules on a background of red and tender skin. Widespread patches may occur randomly on any part of the body. It is also known as acute generalised pustular psoriasis of von Zumbusch.
Localised pustular psoriasis, which appears on the hands or feet (palmoplantar pustulosis) is considered a different skin disorder. This needs to be distinguished from a localised form of generalised pustular psoriasis (for example, affecting knees only).
What causes generalised pustular psoriasis?
In most patients no identifiable cause can be found, i.e. the generalised pustular psoriasis is idiopathic.
Some people with generalised pustular psoriasis have a preceding history of chronic plaque psoriasis, the common variety of psoriasis, in which there are persistent red scaly plaques.
In many patients no identifiable cause can be found for the altered pattern of disease of generalised pustular psoriasis. In some cases possible trigger factors may include:
- Sudden withdrawal of injected or oral corticosteroids
- Drugs such as lithium, salicylates, indomethacin, iodide and some beta-blockers
- Strong, irritating topical preparations such as coal tar, dithranol and strong topical corticosteroids under occlusion
Impetigo herpetiformis was a previous name for generalised pustular psoriasis arising in pregnancy, but this name is no longer used because the eruption has nothing to do with either impetigo (a bacterial infection) or herpes simplex (a viral infection).
What are the signs and symptoms of generalised pustular psoriasis?
In generalised pustular psoriasis, initially the skin becomes dry, fiery red and tender. The patient may also have a fever, chills, headache, rapid pulse rate, and loss of appetite, nausea and muscle weakness. Within hours 2-3 mm pustules filled with non-infected pus appear on parts of the body especially the flexures and genital areas. After a day they coalesce to form lakes of pus, which then dry and peel to leave behind a glazed, smooth surface on which new crops of pustules may appear. Successive crops of pustules may appear and erupt every few days or weeks.
The sudden onset of generalised pustular psoriasis can be quite alarming. If the patient survives the acute phase and its complications, remission occurs within days or weeks and the psoriasis reverts to its previous state or erythroderma may develop. Relapses are common.
What treatment is available for generalised pustular psoriasis?
Generalised pustular psoriasis can be life threatening so hospitalisation is usually required. The aim is to prevent further fluid loss, stabilise body temperature and restore electrolyte imbalance. Characteristically, there is a low level of calcium in the blood (hypocalcaemia). Other changes on blood testing include low plasma albumin and zinc, high ESR (erythrocyte sedimentation rate), raised neutrophil count, reduced lymphocyte count and raised lactate levels.
Affected areas are treated with bland topical compresses. Antibiotics may be prescribed if infection has occurred. In severe cases or cases where recurrent outbreaks have exhausted the patient, systemic medications are used. These include:
- Oral retinoid such as acitretin, derived from vitamin A
- Sometimes it is necessary to restart corticosteroids, usually temporarily
- Other medications such as methotrexate, colchicine, ciclosporin, tioguanine and hydroxyurea have been used with some success.
- Phototherapy (ultraviolet radiation), especially in combination with oral psoralens (PUVA). This is usually started once the patient has been stabilised on acitretin.
What are the complications of generalised pustular psoriasis?
Death can result from cardiorespiratory failure during the acute eruptive phase of generalised pustular psoriasis so it is very important to treat it as early as possible. Elderly patients are at greatest risk. Other complications include:
- Secondary bacterial infection
- Disturbed protein and electrolyte balance, especially low albumin and calcium
- Renal and liver impairment
- Malabsorption of nutrients and therapeutic drugs
- Inflammatory arthritis
Book: Textbook of Dermatology. Ed Rook A, Wilkinson DS, Ebling FJB, Champion RH, Burton JL. Fourth edition. Blackwell Scientific Publications.
On DermNet NZ:
- Psoriasis, Pustular – Medscape Reference
- Pustular Psoriasis – emedicinehealth
- Pustular psoriasis – National Psoriasis Foundation (US)
- MyPsoriasis.co.nz – Information for New Zealand patients with psorasis and psoriatic arthritis, sponsored by AbbVie
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