Uveal melanoma. Comparison of the prognostic value of fibrovascular loops, mean of the ten largest nucleoli, cell type, and tumor size.

PURPOSE: This study was performed to determine the prognostic significance of the presence of loops defined as periodic acid-Schiff-positive fibrovascular septa that completely surround lobules of tumor cells in cases of uveal melanoma.
METHODS: The presence of loops was evaluated using an ordinary light microscope and routinely stained periodic acid-Schiff and hematoxylin sections from 496 posterior uveal melanomas without knowledge of the follow-up data on the patient.
RESULTS: At 15 years, survival decreased from 67.5% to 33.8% when complete loops were present. Univariate Cox regression analysis indicated that the presence of loops was an indicator of poor outcome, and was better than age but not as good as the mean diameter of the largest nucleoli, cell type, or tumor size.
CONCLUSIONS: The presence of loops, as evaluated in this study, was not as strong an indicator of poor outcome as were loops assessed in a previous study of 234 cases from another laboratory. The authors suspect this difference may be due to their only using routinely stained sections without a green filter, as was used in previously reported studies. The authors description of loops does not require any special equipment and gives sufficiently useful results to justify its inclusion by the pathologist in reports of such specimens. A description of vascular loops should be added to the use of the modified Callender cell type, tumor dimensions, mitotic count, extraocular extension, and lymphocytic infiltration in the final pathologic report.