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* = Presenting author

P177 Histological features in paired ileal resections in Crohn's disease patients

Palmela C.*1,2, Torres J.1,2, Huang R.3, Vyas N.4, Zhang X.4, Suarezfarinas M.3,5,6, Cho J.1,6, Colombel J.-F.1, Harpaz N.4, Ko H.M.4

1Icahn School of Medicine at Mount Sinai, Division of Gastroenterology, New York, United States 2Hospital Beatriz Ângelo, Department of Gastroenterology, Loures, Portugal 3Icahn School of Medicine at Mount Sinai, Department of Population Health Science and Policy, New York, United States 4Icahn School of Medicine at Mount Sinai, Department of Pathology, New York, United States 5Icahn School of Medicine at Mount Sinai, Department of Dermatology, New York, United States 6Icahn School of Medicine at Mount Sinai, Department of Genetics and Genomics Sciences, New York, United States

Background

Post-operative recurrence after ileo-colonic resection for stricturing Crohn's disease (CD) is common. The ileal wall in CD can be pathologically heterogeneous, featuring variable combinations of smooth muscle, fibrous and lymphoid tissue as well as edema and lymphatic dilatation. The clinical significance of its composition with respect to disease recurrence is unknown. This study sought to determine whether the composition of recurrent strictures recapitulate those of the primary ileal disease.

Methods

Patients with Crohn's ileitis that required 2 resections, occurring >6 months apart were identified from our archives. The most representative sections of the inflamed ileum in H&E slides were reviewed. For each layer [mucosa, muscularis mucosae (MM), submucosa (SM), muscularis propria inner (MP-I) and outer layer (MP-O), and subserosa (SS)], histological abnormalities were evaluated using a semi-quantitative graded scale (scored −1 to +3). The parameters assessed included layer thickness, expansion of smooth muscle and adipose tissue, and the presence of fibrosis, dilated lymphatics or vessels, inflammatory cells, granulomas, edema, and lymphoid aggregates. All histological analysis was performed by an expert gastroenterology pathologist, who was blinded to the clinical information. Statistical analysis of the paired data was done with equivalence and weighted Cohen's Kappa tests. Correlation (r) value >0.3 was considered meaningful. Cluster analysis was used to identify groups of variables that showed similar results.

Results

Forty four ileal resection specimens from 22 patients (64% were men; mean age at 1st surgery: 32±13y) were retrieved. All surgical specimens presented with expansion of the MM and MP-I. Using the equivalence test, most of the histological features were similar between primary and secondary specimens. The features with highest correlation between the first and second resections were: MP-O inflammatory cells (r=0.78), MP-O and MP-I dilated lymphatics (r=0.46 and r=0.43, respectively), MP-O and SS granulomas (r=0.37 and r=0.35, respectively), SS lymphoid aggregates (r=0.33) and MP-I inflammatory cells (r=0.32). There was a significant clustering for granulomas in different layers between first and second specimens (p<0.05).

Conclusion

To the best of our knowledge, this is the first report describing the histologic features in paired ileal resections in CD patients. The overall histological composition of the specimens was similar between surgeries. MP inflammatory cells and dilated lymphatics, MP-O and SS granulomas and SS lymphoid aggregates were the pathological features that were most likely to be found at reoperation. The presence and severity of granulomas is similar between paired surgical specimens.