Leukocytoclastic Vasculitis in an Adolescent with New-Onset Crohn's Disease.

Extraintestinal manifestations frequently affect patients with inflammatory bowel disease. They can involve virtually any organ, with the musculoskeletal and integumentary systems being the most common. Leukocytoclastic vasculitis is a rare extraintestinal manifestation of inflammatory bowel disease, especially at disease onset. It has been reported to occur in association with Crohn's disease and trimethoprim/sulfamethoxazole (TMP-SMX) exposure independently. We report a case of a 14-year-old female who developed leukocytoclastic vasculitis after exposure to TMP-SMX and was ultimately diagnosed with Crohn's disease. The patient presented with purpura, oral ulcers, abdominal pain, and intermittent bloody stools. Colonoscopy showed colonic inflammation, and biopsies revealed severe chronic active colitis with crypt abscesses. A skin biopsy confirmed the diagnosis of leukocytoclastic vasculitis. Management consisted of high-dose steroids and infliximab, with resolutions of her symptoms. This case emphasizes that extraintestinal manifestations are multifactorial in nature, with the example of an existing genetic predisposition through Crohn's disease and a triggering factor such as TMP-SMX.