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P147. Role of endoscopic biopsy in distinguishing between Crohn's disease and intestinal tuberculosis

R. Thomas1, P. Kakkadasam Ramaswami2, H. Joshi2, N. Toke2, C. Panackel2, S. Mathai2, 1Medical Trust Hospital, Department of Pathology, Ernakulam, India, 2Medical Trust Hospital, Department of Gastroenterology, Ernakulam, India

Background

Distinguishing Crohn's disease (CD) from Intestinal Tuberculosis (ITB) in endemic areas is challenging as both conditions have overlapping clinical, radiological, endoscopic and histological characteristics. The aim of this study was to revalidate existing pathological criteria that have been claimed to be useful in differentiating these two conditions and to identify simple, practically useful parameters.

Methods

Fifty patients with a diagnosis of Ileocolonic Crohn's Disease or Intestinal tuberculosis from July 2011 to April 2013 based on established clinical, endoscopic and histological features and with a follow up for a minimum period of 6 months were retrospectively evaluated. A total of 29 patients with a diagnosis of CD and 21 patients with ITB were included. All patients had undergone full length colonoscopic examination with mucosal biopsies. Upper GI Endoscopy and gastric antral biopsies were available in 24 patients (22 CD and 2 ITB). A total of 109 sites from patients with CD and 34 sites from patients with ITB were studied. Segmental colonic biopsies from 3 or more sites were available in 19 CD patients and 3 patients with ITB. Selected histological parameters which were reported in previous studies as salient distinguishing features between CD and ITB were evaluated.

Results

A morphological diagnosis was possible in 26 cases of CD (90%) and 17 cases of ITB (81%). The features in the remaining 7 cases (3 CD and 4 ITB) were not distinctive enough to make a categorical diagnosis. Endoscopic changes in three or more colonic segments were present in 17/29 cases of CD (58.6%) but only in 5/21 (23.8%) cases of ITB. Terminal ileal involvement was present in all cases of ITB with 16 cases (76%) showing changes at that site only. In contrast, changes restricted to terminal ileum was seen in only 5 cases of CD (17%) and 7 cases showed normal ileal mucosa. Granulomas were present in all the 29 cases of CD (100%) and 19 cases of TB (91%).

The table shows the features of granulomas in our study. Granulomatous inflammation in more than one segment was seen in 85% of CD patients. 16/22 (73%) patients with CD showed focally enhanced gastritis +/− granulomas. Gastroscopy was normal in 12 of these patients indicating the absence of correlation with gastroscopic findings.

Table: Histological parameters in patients with intestinal tuberculosis (ITB) and Crohn's disease (CD)
ITB (n = 21)CD (n = 29)
Caseous necrosis2900
Confluent granulomas7124
>5 granulomas/biopsy4328
Large granulomas573
Pericryptal granuloma548
Microgranuoma1966
Ulcers lined by epitheloid histiocytes4317
Lymphoid cuff6348
Values in are percentages.

Conclusion

In our study, large granulomas and crypt related granuloma were features favouring TB and CD respectively. None of the previous studies have included Gastric antral biopsies which, we feel, significantly increases the diagnostic yield.