Acute generalised exanthematous pustulosis
What is acute generalised exanthematous pustulosis?
Acute generalised exanthematous pustulosis or AGEP is an uncommon skin eruption characterised by superficial pustules.
AGEP is usually classified as a severe cutaneous adverse reaction (SCAR) to a prescribed drug.
What are the clinical features of AGEP?
Typically the AGEP rash 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 generally the patient is not particularly unwell.
The rash may last for one to two weeks and then the skin peels off as it resolves.
Who gets AGEP?
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 AGEP?
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:
- Oral antifungals, particularly terbinafine
- Calcium channel blockers such as diltiazem
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 AGEP diagnosed?
AGEP is often diagnosed clinically. Supportive investigations may include:
- Increased neutrophils (white blood cells) are usually found on blood testing.
- Biopsy of the skin shows subcorneal pustules filled with neutrophils. See dermatopathology of AGEP.
- Patch testing may be used to confirm allergy to an agent causing AGEP.
How is AGEP treated?
New medicines should be discontinued following the onset of AGEP, particularly antibiotics.
What is the outcome for AGEP?
AGEP resolves spontaneously in about 10 days. It does not usually recur, unless the same medication that cause a first episode is taken again.