Three-Dimensional Reconstruction of Extravascular Matrix Patterns and Blood Vessels in Human Uveal Melanoma Tissue: Preliminary Findings

Abstract

Abstract: : Purpose: Looping patterns rich in laminin have been detected in tissue samples of primary aggressive human uveal melanomas and their metastases. Because these extravascular patterns connect to blood vessels and transmit fluid in vitro and in vivo, the three-dimensional configuration of these patterns has been the subject of considerable speculation. We designed methods to describe the three-dimensional configuration of looping extravascular matrix patterns in archival human uveal melanoma tissue. Methods: Twenty-five serial 4 µm-thick sections from primary uveal melanoma tissue were labeled with fluorescent-tagged laminin, examined by confocal microscopy to generate a z-series within each 4 µm-thick section, and the z-series from each section was stacked using an immersive three-dimensional environment (ImmersaDesk®) to allow for precise alignment and compensation for distortion artifact. Results: Extravascular matrix patterns that appeared to form loops in two dimensions were shown to represent thin wrappings around branching and twisting cylindrical groupings of melanoma cells. Blood vessels joined to some of these laminin-positive cylindrical wrappings. Conclusions: In this preliminary study, periodic acid-Schiff (PAS) positive laminin-rich looping patterns seen in two-dimensional tissue sections appear to outline cylindrical branching packets of melanoma cells rather than spheroidal nests. The conduction of fluid through this extravascular system may provide a novel delivery for contrast and diagnostic agents.

Keywords: melanoma • pathology: human • pathobiology