A rapidly developing nonfollicular pustular eruption on diffusely erythematous skin is characteristic of acute generalized exanthematous pustulosis (AGEP), also called toxic pustuloderma. The onset is typically within several days (in one study average 3) of exposure to the offending agent. In 90% or more of cases, the offending agent is a drug, usually an antibiotic, but also other medications e.g., diltiazem, terbinafine, itraconazole, and allopurinol. Infections, especially by Enterovirus and hypersensitivity to mercury may also be implicated. AGEP has followed high-dose chemotherapy [AD 1999;135;1418] and eating a chicken boiled in lacquer.
Patients with generalized pustular psoriasis and a subset of patients with AGEP have been found to have a mutation in the interleukin-36 receptor antagonist (IL-36Ra) [NEJM 2011;18:620–628]. Intraoral pustules have been proposed as a sign of IL-36Ra mutation [JAMA Derm 2015;151;452].
An intense erythema followed by the development of multiple, sterile pustules is typical. Several patients have been noted to have a predilection for the intertriginous areas [AD 1999;135;1418]. Fever, purpura, and targetoid lesions may accompany. Localized pustular eruptions may also occur.
It has been reported that 17% of patients with an AGEP have a history of psoriasis and it is felt that patients with psoriasis are at increased risk for AGEP [Andrew's Diseases of the Skin. Clinical Dermatology 2006].
Patch testing is often but not always positive. A pustular eruption on an erythematous base may be seen.
Exclusion of infection is paramount with the appropriate bacterial, viral, or fungal cultures. Skin biopsy may also be helpful. Systemic involvement was observed in one study in 17% of cases studied, including liver (e.g. elevated LFTs, hepatomegaly), kidney, bone-marrow, and lung (e.g. pleural effusion).
The offending agent should be stopped. Spontaneous healing occurs within 15 days. Some have given prednisone but it is usually not needed. Treatment with a potent topical steroid has been correlated with decreased duration of hospitalization [BJD 2015;172;1455].
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