Pustules in Stevens-Johnson Syndrome

BACKGROUND Stevens-Johnson syndrome (SJS) is characterized by widespread, epidermal necrosis and mucosal involvement mediated by a delayed-type hypersensitivity reaction. Although rapidly progressive epidermal detachment is known to result in blister formation, pustular lesions are rare in SJS. CASE REPORT A 25-year-old male patient with no significant medical history or regular medication presented to the emergency department with a fever and rash. The fever had developed 7 days before the current presentation and was followed 4 days later by lip swelling, conjunctival hyperemia, and sore throat, which caused difficulty with oral intake. Two days before presentation, a generalized rash and dysuria developed, prompting evaluation at our hospital. A clinical examination found multiple, 3-mm pustules surrounding erythema on the face, chest, and back. Scattered erosions were observed on less than 10% of body surface, including the distal extremities, lips, buccal mucosa, and genital area. The conjunctivae displayed marked pseudomembrane formation. Histopathological analysis found that the erosions contained necrotic keratinocytes in the epidermis, with mild vacuolar changes at the dermo-epidermal junction, while the pustules contained serous exudate with scattered neutrophils. Based on these findings, SJS was diagnosed. A drug-induced lymphocyte stimulation test was positive for loxoprofen. The patient responded well to prednisolone therapy. CONCLUSIONS Although no drug exposure or infection preceding the symptoms was identified at admission, SJS was diagnosed by exclusion on the basis of the clinical manifestations and diagnostic criteria. A drug-induced lymphocyte stimulation test may help identify the causative drug. Neutrophilic infiltration into blisters formed by progressive, epidermal necrosis may occasionally result in pustule-like eruptions in SJS.