Diffuse choroidal melanoma. Clinical features predictive of metastasis

C. L. Shields, J. A. Shields, P. De Potter, J. Cater, D. Tardio and J. Barrett
Ocular Oncology Service, Wills Eye Hospital, Philadelphia, Pa, USA.

OBJECTIVE: To assess the clinical features that predict metastasis of diffuse choroidal melanoma. DESIGN: A review of patients who had been diagnosed clinically as having diffuse choroidal melanoma evaluated on the Oncology Service at Wills Eye Hospital, Philadelphia, Pa. MAIN OUTCOME MEASURE: Effect on metastasis of clinical features of the tumor. RESULTS: Of 3500 consecutive patients with choroidal melanoma, 111 (3%) had diffuse choroidal melanoma. Of these 111 tumors, the mean tumor base was 14.7 mm and the mean overall tumor thickness was 2.1 mm. The thickness-to-base percentage averaged 14.8%. The tumor had poorly defined margins in 39 patients (35%), orange pigment on its surface in 49 (44%), and a secondary serous retinal detachment in 76 (68%). Optic nerve invasion was clinically suspected in 2 patients (2%) and transcleral extension in 3 (3%). Initial management was enucleation in 36 patients (32%), plaque radiotherapy in 60 (54%), laser photocoagulation in 3 (3%), and observation in 12 (11%). During a mean follow-up of 5.3 years (median, 3.9 years), metastasis developed in 29 patients (26%). Using Kaplan-Meier survival estimates, the probability of metastasis developing was 16% at 3 years, 24% at 5 years, and 36% at 10 years. The clinical factors predictive of metastasis by univariate analysis included tumor basal dimension 18 mm or more (P = .002), poorly defined tumor margins (P = .03), transcleral extension (P = .003), and optic nerve invasion (P = .03). The clinical factors predictive of metastasis by multivariate analysis included basal dimension of 18 mm or more (P = .01), optic nerve invasion (P = .03), and poorly defined tumor margins (P = .05). CONCLUSIONS: Despite its relative flatness, diffuse choroidal melanoma carries a metastatic potential of 24% at 5 years. The risks for metastasis are greatest with increasing tumor base and poorly defined margins. Recognition of the clinical features of this tumor in the earliest stage and prompt treatment are encouraged.