Table 1.
Histologic classification system of PVN for the Banff Working Group Classification of Definitive Polyomavirus Nephropathy.
| Biopsy-Proven PVN Class 1 | Biopsy-Proven PVN Class 2 | Biopsy-Proven PVN Class 3 | |||
|---|---|---|---|---|---|
| pvl | Banff Ci Score | Pvl | Banff Ci Score | Pvl | Banff Ci Score |
| 1 | 0–1 | 1 | 2–3 | - | - |
| - | - | 2 | 0–3 | - | - |
| - | - | 3 | 0–1 | 3 | 2–3 |
The pvl score is calculated based on the extent of virally induced changes identified on H&E or via SV40 IHC staining. Scores for pvl are calculated as follows: pvl1: ≤1% of all tubules/ducts with viral replication; pvl2: >1 to ≤10% of all tubules/ducts with viral replication; pvl3: >10% of all tubules/ducts with viral replication. The ci score is calculated using the Banff Classification of Renal Allograft Pathology. Ci—interstitial fibrosis; pvl: polyomavirus replication/load level (pvl); PVN: polyoma virus nephropathy.