Table 2: Histopathological features of collagenous colitis and lymphocytic colitis.

Collagenous colitisLymphocytic colitis

(1) Thickening of a subepithelial collagen layer of more than 10 um (1) Intraepithelial lymphocytosis (≥20 IEL per 100 surface epithelial cells)
(2) Inflammation in the lamina propria consisting of mainly lymphocytes and plasma cells (2) Inflammation in the lamina propria consisting of mainly lymphocytes and plasma cells
(3) Epithelial damage, such as flattening and detachment. (3) Epithelial damage, such as flattening and detachment
(4) Intraepithelial lymphocytosis (IEL) could be present, but is not necessary for the diagnosis of CC(4) Subepithelial collagen layer not present or less than <10 um