Allopurinol-Induced DRESS Syndrome: A Reversible Fatality

Abstract

Introduction: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a rare, potentially life-threatening, drug-induced hypersensitivity reaction that includes rash, hematologic abnormalities (eosinophilia, atypical lymphocytosis), lymphadenopathy, and internal organ involvement (liver, kidney, lung). We present a case of DRESS syndrome presenting as elevated liver enzymes after allopurinol exposure. Case Description: A 61-year-old Caucasian male presented to the emergency department with 3 days' history of sore throat, generalized pruritic rash, and dark-colored urine. He reported subjective fever, but denied any associated symptoms. His past medical history was significant for newly diagnosed gout six weeks ago, for which he had been taking allopurinol 200 mg daily. No other change in recent medication was reported. On admission, his temperature was 38.2 C, and physical examination was remarkable for erythematous rash with overlying pustular eruption involving face, trunk, and extremities with normal buccal mucosa. Noteworthy laboratory data included: total bilirubin 2.6 g/dl, AST 74 U/L, ALT 104 U/L, ALP 164 U/L, WBC 15.6 K/cmm, Hb 13.9g/dl, eosinophils 8.4%, and lymphocyte 30%, with atypical lymphocytes predominance. Urine analysis and urine cultures were negative. Renal function was normal. Hepatitis profile was also negative. CT abdomen was unremarkable. Based on the temporal relationship between allopurinol prescription and clinical features of presence of erythematous cutaneous rash without mucosal involvement, eosinophilia, atypical lymphocytosis, signs of visceral involvement presenting as transaminemia and fever, the patient fit the criteria for DRESS syndrome. The patient's allopurinol was discontinued on admission, his symptoms improved, and his liver enzymes trended down. The patient did not require steroids for management. He was followed in outpatient clinic with normalization of liver enzymes and complete resolution of symptoms. Discussion: DRESS is a rare condition with estimated incidence varying from one in 1000 to one in 10,000 drug exposures. The disease is commonly delayed onset, usually 3-6 weeks after drug initiation, and consists of a severe skin eruption, fever, hematologic abnormalities such as eosinophilia or atypical lymphocytes, and internal organ involvement. Liver abnormalities develop in 60-80% of patients. The diagnosis of DRESS depends on high index of suspicion and clinical judgment. Due to the fact that many conditions can present with similar symptoms and signs, DRESS should always be included in differential diagnosis; otherwise, a potentially reversible, yet dangerous, condition can be missed.