Figure 2.

Ancillary staining methods. A: Rectal neuroendocrine tumors show irregular but well-demarcated islands of uniform tumor cells separated by a fibrotic stroma; B: Negative staining for D2-40 reveals retraction cleft from the surrounding fibrotic stroma; C: Lymphatic tumor invasion with thin, endothelial cell lining on H&E is identified; D: The tumor emboli in D2-40-stained lymphatic vessels reveal the recognition of lymphatic invasion; E: Vascular invasion in H&E; F: Elastica van Gieson stain reveals vascular invasion of tumor cells (arrow).