Extreme Positive Patch Test Reaction to Ampicillin 30 Years After Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis

A 50-year-old woman was referred to our allergy department (London, UK) to investigate a historic adverse reaction to ampicillin, which occurred over 30 years ago in her home country of Romania. Five days after commencing oral ampicillin, she developed a prodromal febrile illness, followed by multiple painful erosions and fluid-filled blistering lesions over the face, hands, and torso. She had an estimated 10% to 30% body surface area (BSA) involvement (skin detachment), in addition to associated oral mucosal involvement.