Figure 1

Angiotropism in uveal melanoma. (a) Note large nodular pigmented tumor involving the posterior uveal region. (b) Angiotropism of melanoma (arrow) along posterior ciliary vessels within the sclera at scanning magnification. (c) Melanoma cells are disposed along the abluminal surfaces of the vascular channels (arrows) without intravasation. (d) High magnification shows multi-layered arrangements of pigmented epithelioid melanoma cells (arrows) surrounding this ciliary vascular channel. V=intravascular lumina. Insert: abluminal melanoma cells (arrows) by definition are circumferentially and directly positioned along and in contact with the external surface of this endothelial-lined vascular channel (V). These melanoma cells are in contact with the basement membrane of the endothelial cells. Multi-layering of tumor cells about vascular channels as seen here represents a ‘collective’ form of cellular migration of tumor cells.²⁷