Small Choroidal Melanoma: Correlation of Growth Rate with Pathology.

Purpose: The aim of the study was to evaluate equivalence of growth rate and pathologic confirmation in small choroidal melanoma (SCM).

Design: This study is a case series.

Subjects participants and controls: A total of 61 patients with a choroidal melanocytic tumor of size 5.0-16.0 mm in the largest basal diameter and 1.0-2.5 mm in thickness were classified into the pathology-confirmed group (n = 19), growth-confirmed group (n = 30), and with combined observations (n = 12).

Methods: Distribution of clinical variables (age, gender, laterality, tumor dimensions, tumor location, and presence of orange pigment, subretinal fluid, drusen, and retinal pigment epithelial [RPE] atrophy) between the groups was analyzed. Patient and disease characteristics were summarized as the median and interquartile range for continuous variables and the frequency and percentage for categorical variables. Comparisons were made using the Wilcoxon rank sum test for continuous variables and either Fisher's exact test or the χ² test for categorical variables with a p value threshold of 0.05 for statistical significance. Growth rate (change in basal dimension/12 months) diagnostic of SCM was quantified.

Main outcome measures: The primary aim of this study was to test the hypothesis that "growth" was diagnostic of SCM with the secondary aim of quantifying the malignant "growth rate" (growth rate of SCM).

Results: The clinical characteristics among all 3 groups were similar except more patients with symptoms (68 vs. 20 vs. 42%, p = 0.004) and juxtapapillary location (p = 0.03) were in the pathology group than in the growth-confirmed group. Those in the combined and growth-confirmed groups had more patients with drusen (11 vs. 60 vs. 50%, p = 0.003) and RPE atrophy (11 vs. 23 vs. 67%, p = 0.003), respectively, than in the pathology group. The median time to detect growth was 9 months (range 3-26 months). The mean growth rate in basal dimension was 1.8 mm/12 months (range, 0.0-7.4 mm; [95% CI: 1.32-2.28]).

Conclusions and relevance: Choroidal melanocytic lesions exhibiting a defined growth rate can be clinically diagnosed as SCM without a need for biopsy.