Microcirculation patterns other than loops and networks in choroidal and ciliary body melanomas11None of the investigators has any proprietary interest that could cause or be perceived to be a conflict of interest

Purpose To provide ophthalmologists and pathologists with expanded criteria for separating patients at high risk of metastatic melanoma from those at low risk on the basis of microcirculation patterns in choroidal and ciliary body melanomas. Design Tissue culture studies and observational case series. Participants The pattern-forming ability of four uveal melanoma cell lines of varying degrees of aggressive behavior was studied in vitro. Histologic sections of 234 eyes removed for choroidal or ciliary body melanoma were studied for the presence of microcirculation patterns. Methods The study was divided into two phases: the study of histologic sections of eyes removed for choroidal and ciliary body melanomas and observations on the in vitro behavior of cultured melanoma cells of varying degrees of invasive behavior. The presence or absence of each of nine microcirculation patterns was recorded from tissue sections, and interrelationships between different patterns were explored statistically. In vitro reconstitution of patterns and a study of the interrelationships of patterns in histologic sections was carried out. In the in vitro studies, uveal melanoma cell lines of varying degrees of aggressive potential were cultured to observe the development of architectural patterns other than loops and networks. Main outcome measures In histologic studies, the outcome measure was the conditional probability of detecting loops or networks given the presence or absence of other patterns positive for periodic acid–Schiff. For tissue culture studies, the outcome measure was either the development or lack of development of patterns of different shapes in vitro. Results Histologic studies disclosed that given the presence of arcs without or with branching in a tissue section, it is likely that loops or networks will be detected in the same section plane, suggesting that the production of these patterns by aggressive tumor cells reflects a spectrum of architectural potential. In vitro studies confirmed this hypothesis by revealing that highly aggressive and metastatic uveal melanoma cell lines, but not poorly aggressive tumor cell lines, generated parallel channels with and without crosslinking and arcs with and without branching as well as loops and networks. Conclusions The criteria for separating patients into low- and high-risk categories for metastasis from uveal melanoma should be expanded to include patterns other than loops or networks. In both the pathology laboratory as well as in a clinical setting, the detection of arcs or arcs with branching and parallel channels should prompt a careful search for loops and networks and for crosslinking parallel channels, respectively.