Introduction:
Drug-induced hypersensitivity syndrome also known as DRESS (drug reaction with eosinophilia and systemic symptoms)syndrome, is considered as a severe and potentially life-threatening adverse drug reaction. It is characterized by skin rash, fever, hematologic abnormalities (eosinophilia, atypical lymphocytes), lymphadenopathy and internal organ involvement [1]. Currently, the pathogenesis of DRESS syndrome is only partially understood. Prior research has implicated viral infection or reactivation. It is associated, specifically, with human herpes viruses 6 (HHV-6) and 7 (HHV-7), Epstein-Barr virus (EBV) and cytomegalovirus (CMV)[1,2].
We report a case of DRESS syndrome induced by allopurinol occurring 22 months after starting the treatment and which might have been triggered by concomitant infections.
This case was notified to the Tunisian Center of Pharmacovigilance on December 23th2022 under the registration number3788/22 .
Case report: A 72-year-old diabetic man on insulin, with a history of coronary artery bypass surgery, was put on allopurinol in February 2021 for gout. Twenty months later, (October 22, 2022), he was hospitalized for Klebsiella urinary tract infection associated with erysipelas that had evolved well after two weeks of antibiotherapy (ciprofloxacin and piperacillin-tazobactam). On November 20, he presented a second episode of Enterococcus faecalis urinary tract infection and received teicoplanin for a week. On December 5, he developed a pruritic maculopapular rash with fever estimated at 39.5°C. The eruption first appeared on his legs and quickly proceeded to involve the majority of his body including palms and soles. Skin examination showed a generalized infiltrated erythematous maculopapular eruption (figure 1) and facial edema without poly-adenopathy. Labial mucosa and conjunctivae were not affected. The rest of the physical examination was normal. Complete blood counts showed total leucocyte count at 10.6 × 103/µl with eosinophils at 1.58 × 103/µl (14.9%). Renal and hepatic functions were normal. Histological findings showed vacuolisation of the epidermal basal cell layer and perivascular lymphocytic infiltrate in the dermis, compatible with DRESS syndrome. Allopurinol was stopped. Skin condition improved and laboratory parameters returned to normal rates within a month after the drug withdrawal and using oral corticosteroids (prednisolone).