Utility of colon allograft biopsies in surveillance of patients with small intestinal transplantation – A systematic study of 129 biopsies

Introduction/Objective A segment of right colon is sometimes included with small intestinal allografts to preserve the ileocecal valve and maintain water reabsorption. We correlated pathological findings of colon allograft biopsies obtained during surveillance colonoscopies with clinical, endoscopic, and microbiologic findings. Methods/Case Report All colon allograft biopsies from surveillance colonoscopies over a 3-year period were reviewed for crypt apoptotic activity, cryptitis, lamina propria inflammation, ulceration, and crypt architectural distortion. Clinical and endoscopic findings, and positive cultures a week before and after the biopsies were recorded. Results (if a Case Study enter NA) There were 129 colon biopsies from 29 patients; 98 were histologically normal, whereas 28 showed rare apoptoses (n=14), focal cryptitis (n=8), increased intraepithelial lymphocytes (n=2), moderate acute rejection (n=1), and crypt architectural distortion (n=2). Of these 29 patients, 8 had abnormal endoscopic findings, 21 were normal. Out of 8 patients with abnormal endoscopic exams, 50% had normal histology on biopsy. Twenty-one biopsies were associated with positive cultures in the blood (n=5), urine (n=16) or wound, peritoneal, stool (n=6); 3 had abnormal endoscopies, and 4, abnormal histology. One patient with C.difficle toxin had normal endoscopy and focal cryptitis, whereas another with CMV DNA in blood showed endoscopically congested mucosa and rare apoptoses on biopsy. Of 12 biopsies (7 patients) with abnormal endoscopic findings, (erythema, congestion, ulceration), 4 biopsies had no pathologic findings, 8 had rare apoptosis, and one each had focal cryptitis and chronic colitis. Paired small intestinal biopsies were present with 59 biopsies; 10 showed rare apoptosis and 2, focal cryptitis. Of 70 without paired small intestinal biopsies, there were 5 with rare apoptotic bodies, 5 with focal cryptitis, and 2 with crypt architectural distortion. Conclusion The correlation of histologic, endoscopic, and microbiologic findings in colonic allograft surveillance biopsies is inconsistent. Colon allograft biopsies have limited utility in the follow-up of patients, particularly in absence of paired small intestinal biopsies.

Pathology of Intestinal Transplantation: Rejection and a Case of Tolerance

Small bowel transplants are less common than other organ transplants. Histological criteria for rejection of the transplanted small intestine were proposed at the 8th International Symposium on Small Intestinal Transplantation 2003-2004 [1, 2]. The Banff Conference on Transplant Disease Pathology, an international conference on the rejection of small bowel transplants, was held in 2019, and unifying diagnostic criteria were discussed (https://banfffoundation.org/pittsburgh-2019/). These histological criteria are expected to be standardized in the near future. This review outlines new findings such as apoptosis and apoptotic-body phagocytic findings in the lamina propria and behavior of natural killer T (NKT) cells, in addition to previously known crypt Fas-related apoptosis in acute cellular rejection. Furthermore, we review the case of a recipient who has shown no rejection for 5 years after transplantation. In the transplanted small intestine of this patient, the lymphocytes were replaced by those of another male patient.