Pustular Eruptions

• Acute generalized exanthematous pustulosis (AGEP) is an acute febrile eruption that is often associated with leukocytosis (Fig. 23-2). After drug administration, it may take 1 to 3 weeks before skin lesions appear. However, in previously sensitized patients, the skin symptoms may occur within 2 to 3 days.
• Onset is acute, most often following drug intake, but viral infections can also trigger the disease.
• AGEP typically presents with nonfollicular sterile pustules occurring on a diffuse, edematous erythema (Fig. 23-2).
• May be irregularly dispersed or grouped (Fig. 23-3A), usually starting in the folds (Fig. 23-3B) and/or the face.
• Fever and elevated blood neutrophils are common.
• Histopathology typically shows spongiform subcorneal and/or intraepidermal pustules; a marked edema of the papillary dermis; and eventually vasculitis, eosinophils, and/or focal necrosis of keratinocytes.
• Pustules resolve spontaneously in <15 days and generalized desquamation occurs approximately 2 weeks later.
• Differential diagnosis includes pustular psoriasis, the hypersensitivity syndrome reaction with pustulation, subcorneal pustular dermatosis (Sneddon-Wilkinson disease), and pustular vasculitis.
• Acneiform pustular eruptions (see Section 1) are associated with iodides, bromides, adrenocorticotropic hormone (ACTH), glucocorticoids, isoniazid, androgens, lithium, actinomycin D, and phenytoin. The EGFR tyrosine kinase inhibitors erlotinib, gefitinib, cetuximab, and panitumumab produce pustules that are acneiform but without comedones and erupt in the face (Fig. 23-4A) but can erupt also in atypical areas, such as on the arms and legs (Fig. 23-4B), and are most often monomorphous.