ACUTE LOCALIZED EXANTHEMATOUS PUSTULOSIS: A RARE CUTANEOUS DRUG ERUPTION

Abstract

Introduction Acute localized exanthematous pustulosis (ALEP) is a rare, likely T-cell-mediated immune processes (type-IV-reaction), characterized by pustules typically localized to the face, neck or chest, usually in response to medications. We present a case with cutaneous drug reaction consistent with ALEP following administration of antibiotics. Case Description A 33-year-old woman presented with 3-4 days of painless pustules mostly on her right forehead, but slightly crossing the midline. She denied new topical exposures. However, she reported receiving intravenous ampicillin-sulbactam 4 days prior for purulent cellulitis of the hand, followed by oral amoxicillin-clavulanate. Based on wound culture sensitivities, the antibiotic was later changed to trimethoprim-sulfamethoxazole, of which she had only taken 2 doses of. Initially, her rash was believed to be shingles versus MRSA cellulitis, for which she was started on valacyclovir and vancomycin. However, the patient was afebrile without leukocytosis. On examination, she had multiple superficial pustules without significant erythema, warmth or edema. Due to the lack of typical signs of cellulitis and considering recent antibiotic exposure, the patient was eventually diagnosed with ALEP, with ampicillin-sulbactam or amoxicillin-clavulanate as the most likely culprits. All antibiotics were discontinued. The patient had spontaneous resolution of the rash several weeks following discharge. Discussion ALEP is a rare drug eruption occurring 3-5 days after drug commencement, most commonly associated with aminopenicillins. Major differentials include shingles, acne or bacterial infections. Key differentiating features include acute course, history of recent drug administration and spontaneous resolution following drug cessation. Once ALEP is confirmed, the patient should avoid further use of the trigger medication.