Abstract: Drug-induced hypersensitivity syndrome (DiHS) and toxic epidermal necrolysis (TEN) are widely recognized as two distinct severe cutaneous adverse drug reactions. This paper reports for the first time a case of DiHS complicate with TEN indused by mexiletine. The patient was a 46-year-old female who developed high fever, generalized maculopapular rash, significantly elevated eosinophil percentage, and severe liver function impairment after taking mexiletine hydrochloride tablets for 4 weeks, meeting the diagnostic criteria for DiHS. Subsequently, her condition progressed rapidly to widespread blisters and bullae with epidermal detachment affecting more than 30% of the body surface area, along with extensive mucosal involvement, consistent with a diagnosis of TEN. The patient had a critical and rapidly progressive clinical course. Despite glucocorticoid and anti-tumor necrosis factor therapy, the patient developed respiratory failure and ultimately experienced cardiac arrest. This case illustrates that DiHS and TEN can sequentially coexist and present overlapping manifestations in clinical practice.

Key words: drug-induced hypersensitivity syndrome, toxic epidermal necrolysis, mexiletine, eosinophils, cytotoxic T lymphocytes, hepatic injury