Small metastasizing choroidal melanomas.

Purpose: Small choroidal melanomas have a better prognosis than large tumours. However, these small tumours can spread, often late in their course. The aim of the study was to analyse survival and tumour characteristics of six cases of late metastatic diseases after conservative treatment.

Methods: A retrospective study was conducted at the Croix-Rousse University Hospital of Lyon among 523 patients treated between 1991 and 2010 by proton beam therapy (508) or brachytherapy with 106 (Ru/Rh) (15) for uveal melanomas. We have selected patients with small choroidal melanoma (thickness≤3 mm and diameter≤9 mm) (59 patients), who have developed hepatic metastases (six of 59).

Results: At the time of diagnosis, median age was 57 years (range, 37-82 years). The mean tumour thickness was 2.9 mm (range 2.5-3 mm), and the mean diameter was 7 mm (5-8 mm). Orange pigment was observed in four cases, subretinal fluid was observed in two cases, and one tumour touched the optic disc. Five patients had proton beam therapy. One patient had beta brachytherapy (106 Ru/106 Rh). Average follow-up was 8.3 years (range 4.2-11.8 years). None of the six patients developed local tumour recurrence. The mean survival time after diagnosis of melanoma was 9.8 years (range, 4.9-14.6 years). The average time from treatment of primary tumour to detection of liver metastasis was 7 years (range 3.9-12 years). The mean survival time from the diagnosis of metastasis was 35.2 months (range 9-101 months). Small melanoma-related death was 0% at 3 years, 1.7% at 5 years, 5.1% at 10 years and 10.2% at 15 years in our series.

Conclusions: Despite a small tumoral size and an early and effective local treatment, six of 59 small choroidal melanomas have developed metastasis after local treatment. Small tumours represent a significant risk of metastasis.