Azathioprine Induced Sweetʼs Syndrome in Crohnʼs Disease: An Important Distinction: 2016 ACG Presidential Poster Award

Abstract

Sweet's syndrome (SS), or acute febrile neutrophilic dermatosis, is an inflammatory skin disease that has been described in three distinct clinical scenarios. Classical SS either follows infection or occurs during pregnancy. SS also occurs with inflammatory bowel disease (IBD). Lastly, SS can be an atypical drug reaction. We describe a case of Azathioprine induced Sweet's Syndrome (AISS) in a young male with Crohn's disease. A 35-year-old man with ileo-colonic Crohn's disease presented to the emergency department with rash and fever two weeks after starting azathioprine. Within 48 hours of starting this medication the patient noted a left hand purulent lesion that was drained and treated with cephalexin, without resolution. On admission, physical examination revealed multiple papules and nodules that were not painful. The differential diagnosis included pyoderma gangrenosum, drug reaction, and Crohn's related SS. Skin biopsy revealed a predominantly neutrophilic septal and lobular panniculitis. One week after withdrawal of the medication, the patient defervesced and the skin lesions healed without additional treatment. The non-tender character of the lesions, the onset following introduction of azathioprine, and the rapid resolution with azathioprine withdrawal made AISS the most likely etiology. SS is a neutrophilic dermatosis characterized by the acute eruption of erythematous papules, nodules or plaques which may progress to pustules, bullae or ulcers, with systemic symptoms including fever and leukocytosis. The pathogenesis of the condition is unknown, but thought to involve a local or systemic dysregulation of cytokine secretion. SS can be associated with infection, IBD, pregnancy, malignancy, or certain medications and may necessitate treatment with systemic corticosteroid therapy. The treatment of AISS is unique in that withdrawal of the medication alone leads to resolution of symptoms. Clinicians treating patients with IBD should look for signs of AISS in patients who have recently started azathioprine or 6MP. The syndrome can be misinterpreted as an IBD-associated skin eruption or as infection. It is important to make the diagnosis early, as discontinuation of the drug is the necessary treatment. Re-challenge with azathioprine is not recommended. TPMT status is not thought to be related to the incidence of AISS. Therefore, testing for the genetic polymorphism will not help predict likelihood of this atypical reaction.Figure 1Figure 2