Clinical features of small choroidal melanoma.

The detection and treatment of choroidal melanoma early in its natural course is critical to providing the patient with the best prognosis. Patients with small choroidal melanoma (< 4 mm thickness) develop metastasis in 16% of cases at 5 years follow up, whereas those with medium choroidal melanoma (4-8 mm thickness) and large choroidal melanoma (> 8 mm thickness) develop metastasis in 32 and 53%, respectively. The difficulty with early detection of choroidal melanoma relates to its clinical similarity to benign choroidal nevus. Factors that differentiate small choroidal melanoma from choroidal nevus can be remembered using the mnemonic TFSOM, indicating To Find Small Ocular Melanoma. The letters in this mnemonic represent T (Thickness >2 mm), F (subretinal Fluid), S (Symptoms), O (Orange pigment), and M (Margin touching optic disc). Choroidal melanocytic tumors that display 0 factors have 3% chance for growth at 5 years and most likely represent choroidal nevi. Tumors that display one factor have a 38% chance for growth and those with two or more factors show growth in over 50% of cases at 5 years. Most of those tumors with two or more risk factors probably represent small choroidal melanoma and early treatment is generally indicated. Therefore, ophthalmologists should be aware of the important factors that identify small choroidal melanoma so that early treatment and better life prognosis can be achieved for their patients.