Snapshot A 18-year-old boy presents to his primary care physician for abdominal pain, diarrhea, and chronic fatigue. He reports that he has nonbloody diarrhea for the past few weeks. He could not identify any “bad” foods, and nobody else around him has the same symptoms. His aunt has a history of inflammatory bowel disease, but he is unsure which specific disease. He is noted to be underweight on physical exam. Laboratory results show elevated erythrocyte sedimentation rate (ESR) and C-reactive protein. He is scheduled for a colonoscopy with biopsy to confirm the diagnosis. Introduction Overview Crohn disease is an inflammatory bowel disease that can affect any part of the gastrointestinal (GI) tract, including the mouth and the anus characterized by abdominal pain and nonbloody diarrhea classically associated with non-contiguous involvement, or “skip lesions”, along GI tract Epidemiology demographics onset 15-30 years of age or 60-70s years of age risk factors family history Pathogenesis mechanism chronic Th1-mediated inflammation login to view 1 more bullet Prognosis unpredictable course of relapses and remissions Presentation Symptoms GI symptoms results from transmural involvement abdominal pain bloody or nonbloody diarrhea abscess fistulas strictures malnutrition extraintestinal manifestations arthralgias kidney stones login to view 1 more bullet ankylosing spondylitis gallstones login to view 1 more bullet systemic symptoms chronic intermittent fever weight loss fatigue Physical exam skin and mucosal findings pyoderma gangrenosum erythema nodosum aphthous stomatitis perianal region login to view 2 more bullets ocular finding episcleritis uveitis Imaging Abdominal radiograph indications assess for bowel obstruction CT of abdomen indications evaluation for obstruction, fistulas, or abscesses Studies Serum labs serology used when endoscopic studies and barium studies are inconclusive anti-saccharomyces cerevisiae positive anti-neutrophil cytoplasmic antibody negative complete blood cell count elevated inflammatory markers Invasive studies colonoscopy or esophagogastroduodenoscopy indication login to view 1 more bullet findings login to view 5 more bullets Histology noncaseating granulomas lymphoid aggregates Differential Ulcerative colitis key distinguishing factors bloody diarrhea disease affecting colon and always the rectum mucosal and submucosal inflammation only Treatment Medical 5-aminosalicylic acid agents indications login to view 2 more bullets drugs login to view 3 more bullets corticosteroids indications login to view 1 more bullet immunosuppressive agents drugs login to view 6 more bullets antibiotics drugs login to view 2 more bullets anti-diarrheal medications drugs login to view 1 more bullet Surgical surgical resection of affected area indications login to view 1 more bullet Complications Fistula formation Colorectal cancer Abscesses Strictures