The relationship between combined positron emission tomography/computed tomography and clinical and light microscopic findings in choroidal melanoma

BACKGROUND: To investigate the correlation between the clinical and light microscopic features of choroidal melanoma with combined PET/CT findings. METHODS: This is a retrospective interventional case series of 14 patients with choroidal melanoma referred to the vitreoretinal service at the Mayo Clinic, Rochester, MN. All underwent preoperative combined PET/CT scanning and enucleation. Standardized uptake values (SUV) were correlated with the clinical and light microscopic features of the choroidal melanomas. RESULTS: All 14 eyes showed uptake. The mean patient age was 62 years (SD 12.5 years). The mean tumor thickness was 9.3 mm (range 3-23 mm). Histopathology showed choroidal melanoma in all with the following cell types: 6 mixed cell type, 7 spindle cell type, and 1 epithelioid cell type. The average of the SUV means was 3.7 (range 1.7-12.8). The individual SUV means were correlated with lesion thickness (r = 0.85; P < 0.01) and largest tumor basal diameter (r = 0.65; P = 0.01). Melanomas with focal necrosis (P = 0.03) and of the mixed cell type (P < 0.01) appeared to have higher SUV means. CONCLUSIONS: The majority of the choroidal melanomas had low to medium mean SUVs. Lesion size accounted for a significant portion of the variation, though nonspecific necrosis and cell type were also associated with higher SUV means.