Subcutaneous Histiocytoid Sweet Syndrome Associated with Crohn Disease in an Adolescent

We report a case of subcutaneous histiocytoid Sweet syndrome in an adolescent with Crohn disease. A 14-year-old boy with a 1-year history of ileocolonic and perianal Crohn disease, treated with infliximab and azathioprine, was admitted to the Pediatrics Department with malaise, abdominal pain, bloody diarrhea, and fever (39°C) from 15 days ago. Two days later, he developed cutaneous lesions consisting of tender, erythematous, and violaceous papules and nodules scattered over his legs, soles, and upper extremities. Laboratory studies revealed neutrophilia, microcytic anemia, and elevation of both erythrocyte sedimentation rate and C-reactive protein rate. A skin biopsy specimen showed deep dermal and predominantly septal inflammatory infiltrate in the subcutaneous tissue composed of polymorphonuclears, eosinophils, and mononuclear cells of histiocytic appearance. These histiocytoid cells stained positive for myeloperoxidase. Subcutaneous Sweet syndrome is a rare subtype of acute neutrophilic dermatosis, in which the infiltrate is exclusively or predominantly located in the subcutaneous tissue, causing lobular or septal panniculitis. It is often described in patients with an underlying haematological disorder or caused by drugs, but very rare in patients with inflammatory bowel disease, especially in childhood or adolescence. To our knowledge, this is the first case of subcutaneous histiocytoid type in a paediatric patient. 1. Introduction Sweet syndrome, also referred to as acute febrile neutrophilic dermatosis, is a reactive condition of unknown etiology characterized by an abrupt onset of cutaneous lesions consisting of painful, erythematous plaques, papules, and nodules accompanied by fever and neutrophilia. It has been reported in association with several drugs and inflammatory, neoplastic, and infectious diseases [1]. Cases of Sweet syndrome in patients with Crohn disease have been sporadically reported. Herein, we report a case of this association with the peculiarities being the subcutaneous histiocytoid variant of Sweet syndrome and occurring in an adolescent. 2. Case Presentation A 14-year-old boy with a 1-year history of recurrent ileocolonic and perianal Crohn disease, treated with infliximab and azathioprine, was admitted to the Pediatrics Department with malaise, abdominal pain, bloody diarrhea, and fever (39°C) from 15 days ago. Due to suspicion of concurrent intra-abdominal infection, treatment with teicoplanin, meropenem, and metronidazole was started. Two days after hospital admission, he developed cutaneous lesions consisting of tender,