Urticaria multiforme: a benign frightening rash

Urticaria multiforme in an adolescent: A rare benign rash not to be ignored

“…The most recent case is an 18‐year‐old girl with a COVID‐19 infection simultaneously with the rash 3 . Urticaria multiforme is often associated with an infectious episode, as it was the case with our patient, or following vaccination or medication 5 . Histology shows a localized edema in the dermis with a perivascular and interstitial infiltrate rich in eosinophils and neutrophils with some histiocytic cells, compatible with the diagnosis of urticaria multiforme 6 .…”

“…3 Urticaria multiforme is often associated with an infectious episode, as it was the case with our patient, or following vaccination or medication. 5 Histology shows a localized edema in the dermis with a perivascular and interstitial infiltrate rich in eosinophils and neutrophils with some histiocytic cells, compatible with the diagnosis of urticaria multiforme. 6 Discrete vascular changes may also be seen without strong fibroid necrosis.…”

Time After Time: A Second Look at Evolving Rash With Multiple Exposures to Amoxicillin

“…It is often misdiagnosed as erythema multiforme, but differs in the lack of bullae formation, skin necrosis, and mucosal membrane involvement. The diagnostic criteria include: annular to polycyclic urticarial lesions with transient ecchymotic skin changes, duration of individual lesions lasting less than 24 h, angioedema or acral edema, dermatographism, modest elevation of acute phase reactants, and a favorable response to antihistamines [ 6 ]. In comparison to urticaria multiforme, our patient only had the urticarial lesions with ecchymosis, but did not have the same duration of lesions, angioedema, acral edema, dermatographism, elevation in acute phase reactants, or favorable response to antihistamines until diphenhydramine was switched to hydroxyzine.…”