A choroidal nevus is a benign “growth” of the retina. It may often be described as a “freckle” and is analogous to a mole on your skin. Choroidal nevi are very common and occur in about 5% of the population. They are normal.
A choroidal nevus; however, must be distinguished from a malignant melanoma.
While both a mole and a nevus are benign, malignant change can occur. The chance of a choroidal nevus becoming malignant is very, very small.
A choroidal melanoma is a malignant tumor of the retina. It may spread (metastasize) to other parts of the body and can be fatal.
It may be difficult for your eye doctor to differentiate a choroidal nevus from an ocular melanoma. As a retinal specialist, I am often asked to examine patients to make that differentiation.
So the real question becomes, is this a malignant melanoma or not?
There is no diagnostic test for either a melanoma or choroidal nevus. This means there is no single test that proves the growth is benign or malignant.
Both have similar features: color is slate grey to black, both may be associated with drusen and both are found in the same are of the retina. Evidence of growth, blood or retinal detachment are usually consistent with malignancy.
Your doctor needs to decide if there is cause for concern. If there is any doubt you should be referred to retinal specialist or even an ocular oncologist – an ophthalmologist who deals with ocular tumors.
In most cases, your doctor should be comfortable diagnosing a choroidal nevus.
What Does this Mean?
Most cases of choroidal nevus are very easy to diagnose (for a retinal specialist). Still there are times when I have my doubts and I’ll either refer to a colleague or ocular oncologist for a second opinion.
A choroidal nevus should be examined periodically. A choroidal nevus will not show signs of growth. Because the textbooks teach us that a nevus can transform to a malignant tumor, period re-evaluation is recommended.
If you’ve been diagnosed with a choroidal nevus, ask your doctor for a picture. Date the picture and keep with your files. It will be a huge time saver to your future doctors if you can provide evidence that your nevus has been established, has not grown and is…benign.