Abstract: TH-PO1069
Defining Histologic Features of Ischemia Reperfusion Injury in Kidney Allografts
Session Information
- Pathology and Lab Medicine
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1700 Pathology and Lab Medicine
Authors
- Arevalo Salazar, Dory E., Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Fu, Liying, Mayo Clinic Arizona, Scottsdale, Arizona, United States
- Smith, Maxwell L., Mayo Clinic Arizona, Scottsdale, Arizona, United States
- Ryan, Margaret, Mayo Clinic Arizona, Scottsdale, Arizona, United States
Background
Ischemia reperfusion injury (IRI) is a frequent complication of renal transplantation associated with impaired graft outcomes. Arising from cold and/or warm ischemia followed by reperfusion. Despite its clinical relevance, IRI associated histopathologic features remain incompletely defined. This study characterizes IRI associated changes in renal allografts.
Methods
We retrospectively reviewed 77 time zero or ≤1 week renal allograft biopsies with IRI from deceased donor transplants (2019–2025). Histology was independently assessed by three renal pathologists per 2022 Banff criteria, with clinical correlation from the electronic medical record.
Results
Among 77 biopsies (74 time zero; 2 at 3 days post transplant, and 1 within 7 days), focal glomerular platelet thrombi (85.7%) and endothelial swelling with bloodless glomeruli (81.8%) predominated (Figure 1). Arteriolar endothelial swelling was the most frequent vascular lesion (11.7%). C4d staining was rare, with one positive case in an ABO mismatched transplant (A2→B). Summary of findings per compartment is in Table 1.
Conclusion
IRI is a predominantly microvascular injury marked by early glomerular platelet thrombi and endothelial damage, which must be recognized to prevent misclassification as thrombotic microangiopathy or antibody mediated rejection.
Table 1. Summary of histologic findings per comparment.
| Histological feature | n 77 (%) |
| GLOMERULAR LESIONS Glomerular fibrin thrombi Glomerular platelet thrombi Glomerular neutrophils Glomerular endothelial swelling/bloodless glomeruli Glomeruar karyorrhexis Glomerular necrosis | ----- 11 (14.2) 66 (85.7) 45 (58.4) 63 (81.8) 18 (23.4) 4 (5.1) |
| Parenchymal necrosis Cortical necrosis | 4 (5.1) |
| Vascular lesions Arteriolar fibrin thrombi Arteriolar endothelial swelling/pinpoint Arteries with mucoid change Vascular necrosis | 4 (5.1) 9 (11.7) 3 (3.9) 0 (0) |
| C4d positive within peritubular capillaries | 1 (1/3)* |
*Only 3 cases had C4d staining, with only one positive case (1/3).