Microscopic features of small bowel mucosa of patients with Crohn’s disease

Background Double-balloon enteroscopy enables performing numerous small bowel biopsies for pathologic analysis. However, most histopathological characteristics of Crohn’s disease are non-specific characteristics. We aimed to explore the small bowel mucosal histopathologic characters of Crohn’s disease and identify some disease-specific changes.Methods We included 253 patients without tumors and grouped them into Crohn’s disease, suspected Crohn’s disease, and non-Crohn’s disease groups. These patients underwent double-balloon endoscopy examination and small bowel biopsy at Renji Hospital, Shanghai. All histopathological sections were reviewed, and >20 histopathological parameters were assessed. Immunohistochemistry was conducted when necessary.Results There were different forms of granulomatous lymphangitis on the small bowel mucosa in Crohn’s disease. They showed as various macrophages or epithelioid cells in the lumina of lymphatics or in the center of the villi with or without evident obstruction. These features were only observed in Crohn’s disease patients. Furthermore, they were correlated with granuloma and lymphangiectasia. Additionally, 15 other features showed significant differences among the three groups, and Crohn’s disease patients showed an average of almost seven histopathological characteristics.Conclusions We described the detailed morphologies of granulomatous lymphangitis on the small bowel mucosa and recommend it as a useful histopathological feature for the diagnosis of Crohn’s disease. In terms of specificity and sensitivity, it was superior to non-caseating epithelioid granuloma.