Abstract

Sterile neutrophilic folliculitis is an underrecognized dermatologic feature of inflammatory bowel disease. In this entity, papulopustular lesions develop on the trunk and extremities and pathology shows an amicrobial suppurative and granulomatous folliculitis. Clinically, the pustular eruption may develop with the onset of colitis, an exacerbation of colitis, or a medication-associated flare of colitis. Neutrophilic dermatoses, including suppurative folliculitis, have also been described after azathioprine exposure in azathioprine hypersensitivity syndrome. The syndrome presents within weeks of azathioprine initiation with fever, arthralgias, abdominal pain and cutaneous eruptions with pathology revealing a nonspecific neutrophilic process, including suppurative folliculitis. Identifying azathioprine hypersensitivity syndrome is essential as azathioprine rechallenge can lead to anaphylaxis. We present a 58-year-old male with history of Crohn disease who presented with fevers, chills, abdominal pain, and an acute onset purpuric pustular eruption approximately two weeks after starting azathioprine. Lab work revealed a neutrophilic leukocytosis. Complete infectious work-up was negative. Cutaneous pathology revealed sterile neutrophilic folliculitis. Azathioprine was discontinued, but the cutaneous eruption persisted. Patient was started on intravenous methylprednisolone 1mg/kg with rapid resolution of the rash over the next several days. Sterile neutrophilic folliculitis is a specific dermatologic feature of inflammatory bowel disease. Clinical and pathologic overlap exists with other neutrophilic dermatoses including azathioprine hypersensitivity syndrome making the definitive diagnosis difficult in our case. If the clinical and medication history are suggestive of azathioprine hypersensitivity syndrome, azathioprine avoidance is essential to avoid future life-threatening shock.

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