Cytogenetic results of choroidal nevus growth into melanoma in 55 consecutive cases

PURPOSE: To investigate the cytogenetic results of choroidal nevus with photographically-documented transformation into choroidal melanoma. METHODS: Retrospective analysis of 55 consecutive patients who underwent fine needle aspiration biopsy (FNAB) for DNA isolation and whole genome array based assay for chromosomes 3, 6, and 8 analysis prior to plaque radiotherapy. Tumors with abnormalities in chromosomes 3 and 8 were considered high-risk for metastasis. RESULTS: At diagnosis of choroidal nevus the mean patient age was 57 years (median 57, range 10–83 years). All patients were Caucasian and 36 (65%) were female. At the time of nevus diagnosis, the mean tumor basal diameter was 7.4 mm (median 6.5, range 1.5–18.0 mm) and tumor thickness was 2.2 mm (median 2.2, range 0.5–3.9 mm). The mean interval between diagnosis of choroidal nevus and transformation into choroidal melanoma was 58 months (median 42, range 3–238 months). At the time of melanoma diagnosis, the mean tumor basal diameter was 9.7 mm (median 9.0, range 5.0–19.0) and tumor thickness was 3.5 mm (median 3.4, range 1.3–8.1). Cytogenetic analysis of FNAB-isolated melanoma revealed 25 patients (45%) with high-risk and 30 (55%) with low-risk cytogenetic findings. The rate of tumor growth into melanoma was inversely related to high-risk cytogenetic profile (p = 0.03) as those with fast transformation ≤ 1 year showed high-risk in 80% compared to those with slow transformation > 1 year whoshowed high-risk profile in only 38%. Fast transformation into melanoma conferred a relative risk (RR) of 2.116 for high-risk cytogenetic profile, compared to slow transformation. CONCLUSIONS: Choroidal nevus with rapid transformation into melanoma within 1 year is significantly more likely to demonstrate high-risk cytogenetic profile, at risk for metastatic disease, compared to those with slow transformation.