Kidney biopsy-based histologic classifications of polyomavirus nephropathy
| Classification scheme | Banff ti | Banff IFTA | TC cytopathic changes (%) |
Banff ci | pvl |
|---|---|---|---|---|---|
| AST-IDCOP | |||||
| Class A | 0 | 0 | 1–25 | - | - |
| Class B1 | 1 | 0 | 11–25 | - | - |
| Class B2 | 2 | 1 | 26–50 | - | - |
| Class B3 | 3 | 2 | >50 | - | - |
| Class C | 0–3 | 3 | 1 to >50 | - | - |
| Banff | |||||
| Class 1 | - | - | - | 0, 1 | 1 |
| Class 2 | - | - | - | 2, 3 | 1 |
| Class 2 | - | - | - | 0–3 | 2 |
| Class 2 | - | - | - | 0, 1 | 3 |
| Class 3 | - | - | - | 2, 3 | 3 |
Banff ti: 0, 0–9%; 1, 10%–25%; 2, 26%–50%; 3, >50%. Banff IFTA: 0, 0–9%; 1, 10%–25%; 2, 26%–50%; 3, >50%. Banff ci: 0, 0–9%; 1, 10%–25%; 2, 26%–50%; 3, >50%. pvl: 1, ≤1%; 2, >1%–10%; 3, >10%.
AST-IDCOP, American Society of Transplantation Infectious Disease Community of Practice; ti, total interstitial inflammation; IFTA, interstitial fibrosis and tubular atrophy; ci, interstitial fibrosis; TC, tubular cell; pvl, polyomavirus load.
a)Percentage of parenchyma with any intensity of tubular cell viral cytopathic changes; b)Percentage of tubules/collecting ducts with any extent of staining for simian virus 40 large T antigen by immunohistochemistry; viral cytopathic changes are not required.