Comparison of Transillumination and Histologic Slide Measurements of Tumor Diameter in Uveal Melanoma

Tumor size is an important prognostic factor for deaths due to uveal melanoma. The objectives of this study are: (1) to determine the association between largest tumor diameter assessed by clinical transillumination and largest tumor diameter assessed by measurement of the histologic slide; (2) to predict a clinical transillumination diameter for each enucleation specimen based on the best combination of histologic variables—diameter, height, location, and tumor shape; and (3) to use the predicted transillumination diameter in place of histologic diameter measurement as a prognostic factor for patients treated by enucleation in order to reevaluate previously reported survival outcomes for patients treated by proton beam and enucleation. Comparison of measurements on 40 eyes indicated that transillumination largest diameter measurements were larger than histologic slide measurements (mean difference, 2.87 mm). Multiple linear regression analysis yielded the following equation: transillumination di ameter = [4.73 + (0.58 × histologic diameter) + (0.38 × histologic height) + (1.87 × anterior location)]. Using the actual and predicted transillumination measurements, the results of this study support a previously published report on these data: treatment type, tumor size, and location were predictive of mel anoma-related deaths, metastases, and all deaths.