Acute generalised exanthematous pustulosis

Author: Dr Diana Purvis, Dermatology Registrar, Green Lane Hospital, Auckland, New Zealand, 2008. Updated by Hon Assoc Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, September 2015.


Acute generalised exanthematous pustulosis
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Synonyms:
AGEP, Toxic pustuloderma, Pustular drug eruption, Drug induced toxic pustuloderma
Categories:
Reactions to external agents
ICD-11 MMS:
EH67.0
SNOMED CT:
702617007
Acute generalised exanthematous pustulosis (AGEP)

What is acute generalised exanthematous pustulosis?

Acute generalised exanthematous pustulosis, or AGEP, is an uncommon pustular drug eruption characterised by superficial pustules.

AGEP is usually classified as a severe cutaneous adverse reaction (SCAR) to a prescribed drug. It is also called toxic pustuloderma.

Acute generalised exanthematous pustulosis (AGEP) 

What are the clinical features of acute generalised exanthematous pustulosis?

Typically, AGEP starts on the face or in the armpits and groin, and then becomes more widespread. It is characterised by the rapid appearance of areas of red skin studded with small sterile pustules (small blisters filled with white/yellow fluid). There tend to be more disease in skin folds. Facial swelling often arises.

AGEP may be associated with a fever and malaise, but often the patient is not particularly unwell.

AGEP may last for one to two weeks and then the skin peels off, as it resolves.

Who gets acute generalised exanthematous pustulosis?

AGEP has an estimated incidence of 3–5 cases per million population per year. It occurs in males and females, children and adults.

What causes acute generalised exanthematous pustulosis?

Over 90% of cases of AGEP are provoked by medications, most often beta lactam antibiotics (penicillins, cephalosporins and quinolones). Other drugs that may cause AGEP include:

The onset of AGEP is usually within 2 days of exposure to the responsible medication.

Viral infections (Epstein-Barr virus, enterovirus, adenovirus, cytomegalovirus, hepatitis B virus and others) are common triggers of AGEP in children. Spider bites have also been implicated in some cases.

Recent research suggests that AGEP is associated with IL36RN gene mutations. These genetic abnormalities make the patient more susceptible to pustulosis when prescribed certain medications or when exposed to infection. Similar mutations are also found in some patients with other pustular disorders such as generalised pustular psoriasis, palmoplantar pustulosis and acrodermatitis continua of Hallopeau.

How is acute generalised exanthematous pustulosis diagnosed?

AGEP is often diagnosed clinically. Supportive investigations may include:

  • Blood tests: increased neutrophils (white blood cells) are usually found.
  • Biopsy of the skin: subcorneal pustules filled with neutrophils. See dermatopathology of AGEP.
  • Patch testing: sometimes used to confirm allergy to an agent causing AGEP.

What is the differential diagnosis for acute generalised exanthematous pustulosis ?

The skin conditions that may sometimes be difficult to distinguish from AGEP include:

How is acute generalised exanthematous pustulosis treated?

Patients with AGEP are often admitted to hospital for a few days.

New medicines should be discontinued following the onset of AGEP, particularly antibiotics.

Treatment is then based around relieving symptoms with moisturisers, topical corticosteroids, oral antihistamines and analgesics, until the rash resolves. Systemic therapy is rarely indicated.

What is the outcome for acute generalised exanthematous pustulosis?

AGEP resolves spontaneously in about 10 days. It does not usually recur, unless the same medication that cause a first episode is taken again. A second episode may be more severe. 

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