Anticonvulsant hypersensitivity syndrome mimicking a viral illness with skin rash: a case report

Anticonvulsant hypersensitivity syndrome (ACHSS) is rare and defined by a group of systemic symptoms: a typical clinical triad with skin rash, high fever and lymphadenopathy, with or without multiple organ dysfunctions. Its variable presentation renders diagnosis particularly difficult yet important, as delayed diagnosis can lead to serious complications. We describe a 31-year-old woman sent to the emergency department with symptoms of high fever, peripheral lymphadenopathy, arthralgia, nausea, vomiting and a vesiculobullous eruption resembling measles. First diagnostic hypothesis was that of a viral illness. However, thorough second anamnesis pointed towards a possible drug aetiology, as the patient had been prescribed lamotrigine 8 days prior to admission. Blood analysis showed an inflammatory syndrome, thrombocytopenia and moderate lymphopenia. A few days later, results indicated old immunisation for measles. Skin biopsy revealed dermal inflammation with presence of hypereosinophilia, thereby confirming ACHSS. It is important to recognise and treat this rare reaction to anticonvulsants as early as possible in order to prevent its potentially life-threatening complications.