According to an analysis of over 2,500 eyes, there are seven characteristics of choroidal nevi that indicate those lesions most likely to transform into ocular melanoma.  The risk of transformation increased from 3 to 21 times depending on the number of traits accumulated. The results of this study were published in the August 11^th issue of Archives of Ophthalmology.

Five risk factors were determined in a study in 1995 — thickness greater than 2 mm, subretinal fluid, symptoms, orange pigment, and margin near the optic disc (Shields CL et al. Arch Ophthalmol. 2000;118(3):360-364.) The use of these factors has been helpful in early detention of choroidal melanoma. In this analysis, the researchers looked to further identify these risk factors in a larger group of study subjects.

The records of 2514 eyes with choroidal nevi were retrospectively reviewed; each of these patients had been evaluated with indirect ophthalmoscopy and high-resolution magnification of the nevi itself when possible. The authors found that the median tumor basal diameter was 5.0 mm and thickness was 1.5 mm in the study subjects. Nevus growth into melanoma occurred in 2%, 9%, and 13% of eyes at 1, 5, and 10 years, respectively.

After multivariate analysis, the significant predictors of transformation into melanoma were:

• Tumor thickness >2 mm (P<0.001)
• Subretinal fluid (P=0.002)
• Symptoms, such as decreased vision or flashes (P=0.002)
• Orange pigment (P<0.001)
• Tumor margin within 3 mm of the optic disc (P=0.001)
• Ultrasonographic hollowness (P<0.001)
• Absence of halo (P=0.009)

There is also a mnemonic device to remember these characteristics: “To find small ocular melanoma using helpful hints.” This represents thickness, fluid, symptoms, orange pigment, margin, ultrasonographic hollowness, and halo absence. The median hazard ratio (HR) for the growth of a nevus into melanoma with 1 or 2 risk factors was 3; for those nevi with 3 or 4 factors, the HR was 5; for 5 to 6 factors, the HR was 9; and for all 7 factors, the HR was 21.

The use of this predictor can help ophthalmologists identify those people that are at risk for transformation as noted by the study authors.

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