Fig. 3

a Case 2 (mixed type of ISMC) showing a similar configuration to case 1 i.e. slightly exophytic tumor with a broad undulating base. It was mostly contained by the muscularis propria but a few small foci just managed to push through (stage pT3). (H&E; original magnification × 0.4). b Case 2 highlighting the invasive front of the tumor. It still has a pushing margin but a few groups of tumor cells are breaking off and beginning to infiltrate the underlying muscularis propria. Note the small focus of lymphovascular invasion in the central part of the muscle wall. (H&E; original magnification × 20). c The stratified cells are showing architectural complexity and variegation. (H&E; original magnification × 20). d Field showing a preponderance of signet ring cells in a mucinous background. (H&E; original magnification × 20)