An 11 year-old boy presented with generalized skin rash and fever of two days duration following intake of cefadroxil for the treatment of a boil, 24 hours prior to the eruption. Examination revealed superficial, tiny, non-follicular pustules on an erythematous background particularly involving the abdomen, chest, neck, upper limbs (Fig. 1), back, and buttocks (Fig. 2). The scalp, palms, soles, nails, and mucosae were uninvolved. Systemic examination was unremarkable apart from mild fever. Gram staining and culture of pus taken from the lesions were noncontributory. Histopathology showed spongiosis, sub-corneal pustules, perivascular polymorpho-nuclear infiltrate, and dermal edema. Investigation revealed polymorphonuclear leucocytosis (8x109/L) and normal eosinophil count. Other routine laboratory investigations were normal. A patch test reaction with cefadroxil was positive.

Fig.1 Superficial tiny non-follicular pustules on an erythematous background on abdomen, chest, neck, and upper limbs.		Fig.2 Diffuse non-follicular pustular lesions on an erythematous background.

The diseases considered in the differential diagnoses in this child were impetigo, pustular psoriasis, drug reaction with eosinophilia and systemic symptoms (DRESS), subcorneal pustular dermatosis (SCPD) and acute generalized exanthematous pustulosis (AGEP). The gram staining and bacterial culture were negative thus excluding the diagnosis of impetigo. Absence of any previous history of psoriasis, rapid onset and resolution and histopathologically presence of spongiosis and papillary dermal edema ruled out pustular psoriasis. DRESS was excluded owing to the absence of systemic involvement and eosinophilia. Lack of characteristic lesion with circinate spreading outline and temporal course of the disease with rapid resolution ruled out the diagnosis of SCPD.

Our patient fulfilled all the criteria for the diagnosis of AGEP, which are: the presence of numerous, small (<5mm), non-follicular pustules arising on widespread edematous erythema, pathology revealing intra-epidermal or sub-corneal pustules, fever (>38ºC), blood neutrophilia (neutrophil count >7x109/L) and acute progression with spontaneous recovery within 15 days. Cefadroxil was stopped and the child was treated with topical fluticasone propionate cream resulting in complete healing within two weeks.

AGEP is a rare self-limiting cutaneous reaction pattern induced mostly by systemic drugs and can affect any age group. Most common drugs implicated in the causation of AGEP are antibacterials (particularly betalactams and macrolides), anticonvulsants, and anti-inflammatory drugs. Infection with cytomegalovirus, human parvovirus B19 and Epstein Barr virus, as well as brown recluse spider bites, can rarefy incite AGEP.