Fluconazole-induced drug rash with eosinophilia and systemic symptoms syndrome: a case report

We present a case of a woman with pulmonary coccidioidomycosis who developed drug rash with eosinophilia and systemic symptoms syndrome induced by fluconazole. Our case meets Bocquet's diagnostic criteria and is categorized as "definite" drug rash with eosinophilia and systemic symptoms by the Registry of Severe Cutaneous Adverse Reactions. Drug rash with eosinophilia and systemic symptoms syndrome is a T-cell-mediated type IV hypersensitivity reaction; however, our patient also exhibited a unique symptom-a sensation of "throat closing"-suggestive of angioedema and a Type I hypersensitivity component. This symptom appeared while she continued fluconazole after the onset of drug rash with eosinophilia and systemic symptoms syndrome and recurred upon the initiation of posaconazole. Although both fluconazole and posaconazole belong to the triazole antifungal class, true allergic cross-reactivity medicated by IgE is rare probably due to their structural differences. This suggests cross-reactivity may occur even with structurally unrelated drugs in drug rash with eosinophilia and systemic symptoms syndrome. Clinicians managing suspected cases of drug rash with eosinophilia and systemic symptoms syndrome should promptly discontinue the offending drug and exercise caution when prescribing alternative medications to minimize the risk of further hypersensitivity reactions.