Pediatric Crohn Disease

  • Etiology: idiopathic inflammatory bowel disease that is transmural in nature affecting anywhere in gastrointestinal tract in a non-contiguous manner
  • Imaging: skip lesions, transmural bowel inflammation affecting anywhere in gastrointestinal tract but terminal ileum is classic location, progression is wall thickening -> wall thickening and luminal narrowing -> wall thickening and luminal narrowing and upstream bowel dilation -> penetrating complications
  • US: bowel wall thickening, loss of normal mucosal striation, increased echogenicity of perienteric fat, hyperemia of mesentery
  • CT + MRI signs of active disease: mucosal hyperenhancement, wall thickening, prominent vasa recta (comb sign), mesenteric infiltration of fat, hyperintense on T2, hypoperistalsis, restricted diffusion
  • Complications: stricturing of small bowel resulting in obstruction requiring resection, penetrating fistula + abscess formation requiring drainage, sacroiliitis, primary sclerosing cholangitis, avascular necrosis, pancreatitis, nephrolithiasis, cholelithiasis
  • Clinical: often not endoscopically visible as primarily affects small bowel, therapy is primarily medical

Radiology Cases of Crohn Disease

Small bowel follow through of Crohn's disease
AXR AP from a small bowel follow through shows bowel fold thickening in the proximal ileum in the left lower quadrant and bowel lumenal narrowing in the mid ileum in the midline that continues to the terminal ileum in the right lower quadrant.
CT of Crohn's disease with fistula and abscess
Axial CT with contrast of the abdomen shows a thick-walled mass that is filled with air and oral contrast that is located medial to the oral contrast-filled thickened ascending colon and above the right psoas muscle. An extensive amount of inflammatory change is seen in the mesenteric fat in the right lower quadrant.

Gross Pathology Cases of Crohn Disease

Gross pathological image of Chron's disease
Gross pathological image of the terminal ileum shows markedly thickened intestinal wall and adherent pericolonic fat (“fat-wrapping”).