A 35-year-old recipient receives a deceased-donor renal transplant. Six months post-transplant, he develops a serum creatinine rise from 110 to 185 µmol/L over 2 weeks. Donor-specific antibodies (DSA) are detected and renal biopsy shows C4d-positive peritubular capillary staining with acute glomerulitis and peritubular capillaritis. What Banff classification category best describes this finding?
- A Banff 1A — T-cell mediated rejection with interstitial infiltration
- B Active antibody-mediated rejection (aAMR) — Banff 2023 category II ✓
- C Chronic active T-cell mediated rejection
- D BK polyomavirus nephropathy
Explanation
Active antibody-mediated rejection (aAMR) requires three criteria per Banff 2019/2022: (1) histological evidence of acute tissue injury (glomerulitis, peritubular capillaritis, thrombotic microangiopathy), (2) evidence of antibody interaction with endothelium (C4d positivity, elevated TCMR scores, or endothelial gene expression profile), and (3) circulating DSA. C4d-positive staining in peritubular capillaries combined with microvascular inflammation (glomerulitis + peritubular capillaritis) and DSA fulfills all three criteria for aAMR. Banff 1A involves T-cell mediated interstitial nephritis without microvascular changes. BK nephropathy shows intranuclear viral inclusions on biopsy.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.