Outcome of untreated grade II rejection on solitary pancreas allograft biopsy specimens

Background. The most widely used grading scheme for acute pancreas allograft rejection grades biopsy specimens from 0 (normal) to V (severe rejection). Although the more advanced grades correlate strongly with immunologic graft loss, it is unclear how lesser grades impact graft outcome. The authors therefore report the outcomes of untreated grade II (minimal) rejection of solitary pancreas biopsy specimens. Methods. The authors retrospectively analyzed all solitary pancreas transplants performed at the Mayo Clinic between January 2001 and November 2002. The authors selected all patients who were found with grade II findings on biopsy. Whether patients underwent follow-up biopsies, what the results were, and graft survival at the end of the study period were then determined. Results. A total of 88 pancreas transplants were performed; 20 pancreas transplant recipients (23%) developed grade II (minimal) rejection and were followed for a mean of 22.8±8.7 months. Eighteen patients underwent biopsy for protocol purposes and two patients underwent clinically indicated biopsies. Of the patients who underwent biopsy as per protocol, 15 of the patients had a total of 25 follow-up biopsies: 10 were grade 0; 3 were grade I; and 10 were unchanged (grade II). Rejection in one patient progressed to grade III and in another patient to grade IV. The three patients who did not undergo repeat biopsy had a functioning allograft pancreas at the end of the study period. Of the two patients with grade II biopsy specimens obtained for clinical reasons, one had resolution of all inflammation noted on three follow-up biopsies, and the other patient did not undergo follow-up biopsy and died with a functioning graft. Conclusions. Grade II (minimal) rejection of solitary pancreas allograft rarely progresses to more severe degrees of inflammation. Morphologic findings in this category may not have unfavorable prognoses over a period of 2 years when untreated.