Table 1.

Histopathologic injury scoring scheme for cardiac lesions.

Myofiber degeneration	0	Absent
	1+	single to multiple foci of vacuolated, shrunken, or fragmented, hypereosinophilic myofibers
	2+	more frequent multifocal foci to larger zones of vacuolated, shrunken, or fragmented hypereosinophilic myofibers
	3+	Large coalescing to regionally extensive zones of vacuolated, shrunken, or fragmented hypereosinophilic myofibers
Myocardial hemorrhage	0	Absent
	1+	Focal to multifocal mild myocardial, epicardial, or endocardial hemorrhage
	2+	Moderate multifocal to regionally extensive myocardial, epicardial, or endocardial hemorrhage
	3+	Severe regionally extensive hemorrhage involving large portions of heart section
Interstitial edema	0	Absent
	1+	Mild and multifocal separation of myofiber bundles or expansion of perivascular spaces
	2+	Moderate and multifocal separation of myofiber bundles or expansion of perivascular spaces
	3+	Marked regionally extensive or multifocal separation of myofiber bundles and perivascular spaces
Endothelial changes	0	Absent
	1+	Plump endothelial cells, separation of endothelium from underlying basal lamina
	2+	Cellular infiltration of vessel wall or disruption of layers of vessel wall
	3+	Necrosis or severe vascular cellular infiltration