Authors: Allan Zhou , Eden Chan , Eunizar Omar

Abstract

Background: Fixed drug eruptions (FDEs) are a form of delayed-type hypersensitivity mediated by CD8+ T cells triggered by offending agents resulting in recurrent lesions. Multifocal bullous subtypes are rarer but do exist and can mimic other blistering diseases posing a diagnostic challenge in the emergency department setting.

Case Presentation: A 54-year-old Malay lady presented to the emergency department with a painful blistering rash over bilateral extensor forearm and elbow. They appeared as dusky, well-demarcated round plaques with central tense bullae. She had six to seven similar episodes over the past two years, recurring every three to four months with self-resolution each time. Skin biopsy demonstrated superficial perivascular dermatitis with pigmentary incontinence. Direct immunofluorescence and autoimmune serology with blistering disease BP 180 and BP 230 were negative. These findings support a diagnosis of probable multifocal bullous fixed drug eruption. The culprit agent was not identified, and the patient was advised for cessation of potential triggers.

Conclusion: Early dermatology review with skin biopsy in patients presenting with blistering diseases is important for accurate diagnosis and to exclude other life-threatening blistering diseases. FDE may occur without clearly identifiable drug triggers and thorough history taking is essential.

Keywords: Fixed drug eruption, bullous dermatoses, adverse drug reaction, emergency medicine.