Background: Intestinal transplantation (ITx) has evolved to include the ileocecal valve and the colon in order to improve fluid balance. A major challenge in the management of ITx recipients remains the high incidence of acute cellular rejection (ACR). The diagnosis of significant ACR is based primarily on biopsies (Bx) at ileoscopy and limited data exist on interpretation of colonic Bx after ITx.

Goal: To compare the diagnosis of ACR based on endoscopic Bx done at the same time in both the small bowel (SB) and colonic grafts (paired Bx).

Methods: Retrospective study including all patients who received an ITx including colon at Mount Sinai Medical Center between 07/20/2009 and 01/01/2013. All paired endoscopic Bx were included. Using VIII International Small Bowel Transplant Symposium criteria for small bowel Bx and modified criteria for colon Bx, ACR was classified as follows: no ACR (including indeterminate for ACR), mild, moderate and severe ACR.

Results: Twenty-two of 29 ITx during the study period included colon and were performed in 20 different patients. The median age at ITx was 44.9 y (2.9 - 66.3). Intestinal failure was primarily due to Crohn’s disease (4 cases) and major bowel resections related to desmoid tumor or mesenteric ischemia (3 cases each). The median follow-up among survivors was 500 days (69 – 1320). Of a total of 154 Bx, 56 (36.4%) were paired Bx. Among those, 38 (67.9%) showed no ACR in the SB and the colon, 5 (8.9%) showed ACR in the SB and no ACR the colon (4 cases of mild ACR and 1 case of severe ACR) and 13 (23.2%) showed ACR in both Bx. Among those, 3 (in 2 different patients) showed severe ACR in both the SB and the colon and 10 showed mild ACR in both Bx. Fifty-one out of 56 paired biopsies were in agreement regarding the presence or the absence of ACR, giving a correlation coefficient of 0.779. Also, a diagnosis of ACR in the SB was statistically associated with ACR in the colon (p < 0.0001). All 3 cases of severe ACR in both Bx and the case of severe ACR restricted to the SB were treated with IV corticosteroids or thymoglobulin. Among the 10 cases of mild ACR in both the SB and colonic Bx, 5 were treated with increased baseline immunosuppression or IV corticosteroids. None of the 4 cases of mild ACR restricted to the SB were treated as ACR. Of note, only one case of CMV (inclusion bodies and positive immunohistochemical stain) was diagnosed and these abnormalities were restricted to the SB Bx.

Conclusions: This retrospective study shows that, in the majority of cases, paired Bx in the SB and the colon are in agreement regarding the presence or the absence of ACR. However, the criteria for the diagnosis of ACR in the colon are not as well established as those for the SB. Also, in this study, one case showed severe ACR in the SB when there was no sign of ACR in the colonic Bx. Our limited experience suggests that colonic Bx alone may not suffice to exclude ACR following ITx.