Significance of quantifying and localizing vascular networks in choroidal and ciliary body melanomas

Purpose: To determine the significance of quantifying the area occupied by vascular networks and parallel with cross-linking patterns in choroidal and ciliary body melanomas and to determine the most likely location of these prognostically significant stromal-vascular formations. Methods: From a previously studied group of 234 eyes removed for ciliary body or choroidal melanoma, 152 cases were identified that contained networks or parallel with cross-linking. The total cross-sectional area occupied by tumor and the total area occupied by each of the two vascular patterns were calculated from digitized images of histologic sections. The location of these patterns was mapped within the tumor. Results: A revised Cox regression model was generated: (1) the presence of networks, (2) total cross-sectional area, (3) percentage area occupied by networks and parallel with cross-linking, (4) mitoses, (5) tumor infiltrating lymphocytes, (6) the presence of parallel with cross-linking and (7) arcs (model X²=108.962, df=11, P=0.0001). Networks and parallel with cross linking tend to appear at the tumor periphery, defined by the zone encompassed by 1/8 of the diameter of the largest circle that fits within a tumor (P<0.0001). Conclusions: The variable of cross-sectional tumor area replaces largest tumor dimension in the Cox model. The combined percent areas of networks and parallel with cross-linking adds prognostic information to the model. These patterns tend to appear in the tumor periphery. These observations may be useful in developing clinical imaging techniques to assess clinically the biological behavior of ciliochoroidal melanomas.