Table 1.

Scoring matrix for the histology examination

Score	Area affected	Epithelial degeneration/necrosis	Inflammation
0	none	None	None
1	5–10%	Minimal; scattered cell necrosis/vacuolation affecting 5 to 10% of tissue section	Minimal; scattered inflammatory cells affecting 5–10% of tissue section
2	10–25%	Mild; scattered cell necrosis/vacuolation	Multifocal, few inflammatory cells
3	25–50%	Moderate; multifocal vacuolation or sloughed/necrotic cells	Thin layer of cells (<5 cell layer thick)
4	50–75%	Marked; multifocal/segmental necrosis, epithelial loss/effacement	Thick layer of cells (>5 cell layer thick)
5	>75%	Severe; coalescing areas of necrosis, parenchymal effacement	Confluent areas of inflammation