Table 3.

Histological grading of BKVAN–2018 Banff classification.

Class 1		Class 2		Class 3
PyVL	ci score	PyVL	ci score	PyVL	ci score
1	0–1	1	2–3	-	-
-	-	2	0–3	-	-
-	-	3	0–1	3	2–3

PyVL was semiquantitatively assigned based on the overall percentage of tubules in the cortex and medulla with morphologic evidence of polyomavirus replication. A tubule with intranuclear viral inclusion bodies (type 1 or 2) and/or a positive immunohistochemistry reaction for SV40 large T-antigen in one or more cells per tubular cross section is considered “a positive tubule.” The overall percentage of positive tubular cross sections is estimated in the entire biopsy sample (all available cores, cortex, and medulla). PyVL score 1: ≤1%; PyVL score 2: >1% and ≤ 10%; PyVL score 3: >10% positive tubules/ducts. ci score 0: ≤5%; ci score 1: >5% and ≤25%; ci score 2: >25% and ≤50%; ci score 3: >50% of interstitial fibrosis in cortical area.