Fig. 5

Histological findings of the lesion. a Whole mount view of the lesion (H&E staining). b Whole mount view of the lesion (immunostaining of alpha-smooth muscle actin). The close up images of the boxed areas with alphabetical indications in a and b are shown in each corresponding figure. c, d Disruption of the muscularis propria of the appendix (arrows). e, f Photographs showing the invagination of the mucosal layer of the appendix into the submucosa of the adjacent cecum. g The lumen of the cystic lesion was covered by nonneoplastic colonic mucosa. h Communication between the lumen of the cyst and the cecum (arrowheads). Asterisks indicate the lumen of the cystic lesion. Microscopic images were acquired by the use of a light microscopy (BX43; OLYMPUS, Tokyo, Japan) equipped with the image processing software cellSens (OLYMPUS). Scale bars; 1 cm (a, b); 2 mm (c, d, h), 1 mm (e, f); 0.5 mm (g)