Azathioprine Hypersenitivity: a Sweet-like Syndrome

Abstract Introduction: Azathioprine is a purine analog used to treat autoimmune diseases and steroid refractory chronic diseases. Azathioprine hypersensitivity can present occasionally within weeks of initial therapy as Sweet-like Syndrome. Case Summary: A 35 year old woman with Systemic Lupus Erythematosus (SLE) presented to the emergency department with complaints of generalized maculopapular rash, facial swelling and bilateral lower extremity edema of 4 days duration and two day history of constitutional symptoms like fever and nausea within two weeks of beginning of Azathioprine therapy to treat existing Lupus Nephritis (⅔). Reason for the Report: Extensive skin signs include Erythema nodosum, small vessel vasculitis, acute widespread exanthematous pustulosis, sweet syndrome, and nonspecific dermatosis can be seen in patients with azathioprine hypersensitivity syndrome. It is known that the drug's imidazole component interacts with particular proteins to produce haptens, which further trigger Type 3 hypersensitivity reactions. Outcome: Our case demonstrates the very fast onset of Azathioprine-induced Sweet-like Syndrome that happens after taking the offending medication. After ruling out viral and autoimmune reasons, this diagnosis can be made using routine laboratory tests and the results of a skin biopsy. The use of corticosteroids coupled with the discontinuation of azathioprine led to the complete disappearance of symptoms.