The spatial distribution of monosomy 3 and network vasculogenic mimicry patterns in uveal melanoma.

Purpose: Monosomy of chromosome 3 and network vasculogenic mimicry patterns are associated with death in patients with uveal melanoma (UM). Networks are typically found in confined areas within the tumor, whereas the intratumor distribution of chromosome 3 aberrations is unknown. This study was conducted to assess the spatial correlation among chromosome 3 aberrations and networks in UM.

Methods: Vasculogenic mimicry patterns, proliferative activity, and cell type were characterized in 15 enucleated eyes with primary UM. Cells were isolated by laser capture microdissection (LCM) from two tumor regions and one normal retina area from each tissue block. In the eight tumors containing networks, the cells were microdissected from one area with networks and a different area without networks. In seven tumors without networks, cells were microdissected from two distinct tumor areas. The presence of chromosome 3 aberrations was assessed by microsatellite analysis (MSA) in each LCM sample.

Results: Useful MSA data was obtained from 43 of the 45 samples. Monosomy 3 was detected in 16 samples of eight tumors. There was no intratumor heterogeneity for monosomy 3, regardless of the existence of heterogeneity in networks, cell type, or proliferative activity across the two samples from the same tumor. Networks were associated with the presence of monosomy 3 throughout the entire tumor (P = 0.02).

Conclusions: Of the histologic prognostic factors of metastasis in UM studied, only the presence of a network vasculogenic mimicry pattern but not its location is associated with monosomy 3. This suggests that monosomy 3 may contribute to but is not sufficient for the development of the network pattern.