Table 1.

Histopathological scoring system for radiation-induced bowel injury

Item	Scorea
Mucosal erosions/ulcerations	0: Absent
	1: Superficial erosions
	2: Ulcerations
Nuclear abnormalities of epithelial cells (Surface & Crypt)	0: Absent
	1: Hyperchromatic, enlarged nuclei with irregular contours; atypical mitotic figures
Crypt disarrangement	0: Absent
	1: Crypt disarray
	2: Crypt distortion with branching or shortening
Mucosal inflammatory infiltrate	0: Absent
	1: Mild increase in cellularity of the lamina propria
	2: Moderate increase in lymphocytes and plasma cells; eosinophilic crypt abscess
	3: Marked increase in lymphocytes and plasma cells with aggregation as ulcerative colitis
Mucosal edema	0: Absent
	1: Broadened mucosa with scattered cellularity
Fibrosis of the lamina propria	0: Absent
	1: Increase in hyalinized collagen fibers
Fibrosis of submucosa	0: Absent
	1: Mild increase in broadened and hyalinized collagen fibers
	2: Moderate increase in dense collagen fibers; increased submucosal thickness
	3: Marked fibrosis including muscularis
Sclerosis of submucosal vessels	0: Absent
	1: Fibromuscular thickening of the intima
	2: Moderate thickening of the intima with luminal stenosis
	3: Extreme sclerosis with marked stenosis or occlusion
Lymph congestion	0: Absent
	1: Dilated lymph vessels or cystic collections of lymph

^aThe total score of nine items ranges from 0 to 17. A higher score indicates aggravated radiation damage.