Abstract:
To calculate the sensitivity and specificity of the COMS classification of small choroidal melanocytic lesions (SCML) and identify the optimal size criteria for defining small choroidal melanoma.
A cohort of 240 patients with a presumptive diagnosis of SCML that were followed prospectively to document growth prior to treatment formed the basis of the study. If a tumor grew, it was classified as melanoma. The COMS classification was dichotomized, with those having largest diameter > 5 mm and thickness > 1mm classified as melanoma and any smaller lesion classified as a nevus. To find the criteria that best separated melanoma and nevus groups based upon size alone, the sensitivity and specificity for all combinations of largest diameter and thickness cut points were calculated. The combination that yielded the largest sum of sensitivity and specificity was selected as the optimal size criteria for the cohort.
11 SCML (4.6%) demonstrated growth and were classified as melanoma. Using COMS classification, sensitivity was 0.91 (95%CI: 0.62, 0.98) and specificity was 0.39 (0.33, 0.45). Optimal size classification of largest diameter > 4.0mm and thickness > 1.75mm yielded sensitivity of 0.82 (0.52, 0.95) and specificity of 0.76 (0.70, 0.81).
Within the limitations of a size–based classification, modification of COMS size criteria can increase sensitivity and specificity of diagnosing a small choroidal melanoma at presentation. Additional qualitative features must be considered to improve upon diagnostic criteria.
Keywords: oncology • melanoma • choroid