## Diagnostic Approach to Suspected Oesophageal Crohn's Disease ### Why Colonoscopy with Ileoscopy is the Gold Standard **Key Point:** Colonoscopy with ileoscopy and multiple biopsies is the investigation of choice to confirm Crohn's disease because it allows direct visualisation of the colon and terminal ileum—the most commonly affected sites—and permits histological confirmation of non-caseating granulomas. **High-Yield:** Crohn's disease is a transmural inflammatory bowel disease that classically affects the terminal ileum and colon in >90% of cases. Oesophageal involvement is rare (<1%) but when present, it indicates systemic disease. Confirming the diagnosis requires: 1. Endoscopic visualisation of typical lesions (cobblestone appearance, aphthous ulcers, skip lesions) 2. Histological evidence of non-caseating granulomas (present in ~30–50% of cases) 3. Exclusion of other causes (tuberculosis, sarcoidosis, malignancy) ### Diagnostic Criteria for Crohn's Disease | Finding | Significance | |---------|-------------| | Non-caseating granulomas on biopsy | Highly specific (>90%) when present | | Skip lesions (discontinuous involvement) | Pathognomonic for Crohn's | | Transmural inflammation | Distinguishes Crohn's from ulcerative colitis | | Terminal ileal involvement | Present in >90% of Crohn's cases | | Cobblestone mucosa + fissuring ulcers | Endoscopic hallmarks | **Clinical Pearl:** Even when oesophageal involvement is suspected, the diagnosis of Crohn's disease is confirmed by examining the lower GI tract (colon and ileum), as this is where histological confirmation is most reliable and disease burden is greatest. ### Why Other Investigations Are Insufficient **Tip:** Remember that investigations supporting Crohn's diagnosis must include both endoscopic AND histological evidence. Imaging and biomarkers are adjunctive only.
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