Ocular Melanomas

by Richard Mitchell, MD, PhD

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    00:02 Welcome back, to the final chapter in our discussion of optimal logic pathology.

    00:08 We're going to finish up here with ocular melanomas.

    00:12 And although we think of melanoma as being primarily a tumor of skin, they can also occur in the eye.

    00:21 And with some devastating consequences.

    00:24 Just as a trigger warning, some of the images are not particularly attractive.

    00:30 I will try to give you a warning.

    00:32 But know, that this is just the way that pathology looks.

    00:38 Okay. With that warning, let's get going.

    00:41 The epidemiology of ocular melanoma.

    00:44 So, if you stopped and thought about it for a minute, you'd say, "Well, I would expect that ocular melanoma would occur in areas where there are more pigmented cells.

    00:54 So I would expect it to be really, really common in the iris." Not so much.

    00:59 Actually, the choroid has the greatest density of ocular melanoma.

    01:04 So, about 80% of eye melanomas will occur in the choroid.

    01:09 And we don't really think about the choroid is having, you know, a lot of pigmented cells, but yet, there are melanocytes that are there.

    01:16 The ciliary body is kind of next.

    01:19 And although it doesn't have particularly a lot of pigmented cells, there are melanocytes that are present there.

    01:27 So, about 10%.

    01:28 And then iris and conjunctiva come in kind of a distant third, overall.

    01:33 So, most of these are going to be choroidal.

    01:35 And, so therefore, they won't be necessarily directly visualizable.

    01:40 If you get a melanoma of the iris, you're going to kind of know about that.

    01:44 If you get a melanoma of the choroid you may not.

    01:48 The peak incidence is 50 to 70.

    01:50 So, it tends to be a disease of older folks.

    01:53 So, those medical students on this session shouldn't worry about it too much yet.

    01:57 But as you get older, there's increasing incidence.

    02:01 So, what are the risk factors for this? So, light skin color, so melanomas in general, will have certain risk factors.

    02:08 And all those risk factors are also going to be largely the same, when we talk about ocular melanomas.

    02:14 What's shown in the green box is actually an iris melanoma.

    02:18 It's just because it's a good image, and melanomas are going to typically be pigmented black lesions.

    02:25 Light skin color put you at increased risk, probably because you have a potential for greater UV penetration, and therefore, a greater propensity to cause mutations in melanocytes.

    02:38 If you have a number of cutaneous nevi, that is particularly those that are atypical, that will put you at increased risk, because you probably have atypical ocular melanocytes.

    02:50 Light eye color allows more UV light through.

    02:54 If you have existing nevi in the eye, that typically will put you at a slightly increased risk.

    03:01 And obviously, if you have choroidal nevi, and those men, most of us who might have choroidal nevi won't know about that until you have your first optimal logic exam, because there's just absolutely no manifestations.

    03:17 So, one of those not so pleasant pictures.

    03:20 The mortality rate is dependent on which part of the eye is involved.

    03:27 So, the ciliary body has about a 30-50%, 5 year survival rate.

    03:34 Melanoma of the iris much worse, actually.

    03:38 So, it depends.

    03:40 And remember the vast majority 80% of melanomas are going to be coronal.

    03:45 So, that gives the following statistics than last two bullet points, since most of the melanomas are going to be choroidal.

    03:54 It doesn't necessarily follow those statistics for the ciliary body in the iris.

    03:58 If you catch it at an early stage when it does not spread to surrounding tissues or nodes, overall, you have an 85% 5 year survival.

    04:06 Now, it's very likely that it will catch up with you at 10 years, but at least at five years, it's pretty good.

    04:12 And then, if it's spread to surrounding tissues, and or nodes, then it's a 71% survival.

    04:23 What are the signs and symptoms? Again, we're showing you, actually now, a nevus that is on the eye itself, kind of in the conjunctiva.

    04:37 But this will hold true for a whole variety of melanomas including those that are predominant within the choroid.

    04:44 In the choroid in particular, you will tend to get blurry vision because you are distorting how the retina sits relative to where the focal point is of what the lens is bringing in terms of light.

    04:56 So, you'll have blurry vision, and depending on the size of the tumor, you may have distorted vision just because of the tumor mass.

    05:03 In the choroid, you may have visual field defects.

    05:06 So, a choroidal melanoma is much more likely to do that.

    05:09 The conjunctiva melanoma that's been shown here probably not so much.

    05:14 You may have abnormal inhomogeneities within the vitreous fluid.

    05:23 And so that may give rise to floaters, in the field of vision.

    05:28 And you may also have flashes of light so called photopsia.

    05:33 And again, this is because of tumor that sits mostly within the choroid.

    05:38 Tumor of any form, in any place, will likely distort the pupil shape, and that can lead to changes in vision.

    05:49 Defined the coronal melanoma, you'll see a darkened subretinal mass.

    05:53 So, this is something that would show up on our fundoscopic exam, but might not otherwise be visually apparent.

    06:00 And with that, we kind have covered melanomas of the eye and we are at an end of ophthalmologic pathology.

    06:10 With this, this gives you a good start to think about ophthalmology, think about diseases of the eye, and hopefully, you had a better understanding of how the eye is assembled. It's an incredible structure.

    06:21 And without that, you wouldn't even be able to watch what we've just done.

    06:26 And with that, we'll close.

    About the Lecture

    The lecture Ocular Melanomas by Richard Mitchell, MD, PhD is from the course Trauma and Neoplasms of the Eye.

    Included Quiz Questions

    1. Choroid
    2. Iris
    3. Ciliary body
    4. Conjunctiva
    5. Cornea
    1. Choroid
    2. Ciliary body
    3. Conjunctiva
    4. Iris
    5. Cornea
    1. Distortion of pupil shape
    2. Floaters
    3. Photopsia
    4. Visual field defect
    5. Blurry vision
    1. ...melanoma of the choroid.
    2. ...melanoma of the iris.
    3. ...melanoma of the conjunctiva.
    4. ...melanoma of the ciliary body.
    5. ...melanoma of the cornea.

    Author of lecture Ocular Melanomas

     Richard Mitchell, MD, PhD

    Richard Mitchell, MD, PhD

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