Choroidal Nevus

Features


Choroidal nevus is the most common benign intraocular tumor, found predominantly in Caucasian patients. The estimated prevalence is approximately 5% in U.S. adults. Several clinical features allow identification of nevus and differentiation from melanoma. This tumor carries risk for visual acuity loss, especially if near the foveola, and risk for transformation into malignant melanoma.


92.1.1 Common Symptoms


Typically asymptomatic; fluid leakage and neovascularization can result in photopsias and/or loss of vision.


92.1.2 Exam Findings


Flat or minimally elevated mass with brown pigmentation (melanotic; pigmented) or without pigmentation (amelanotic; nonpigmented), generally in the postequatorial fundus (91%) and pigmented (77%), equivalent distribution in all quadrants, and most likely extrafoveolar (94%) compared to subfoveolar (6%). Overlying drusen common, particularly as the patient ages (▶ Fig. 92.1). Tumor size varies depending on the study, but one ocular oncology clinic-based center found mean basal tumor diameter was 5 mm and thickness was 1.5 mm, compared to a population-based study where choroidal nevus was found to have mean basal diameter of 1.25 mm. Choroidal nevus can be categorized into low or high risk for transformation into melanoma.



Fundus photographs of choroidal nevi with overlying (a) mild and (b) extensive drusen.


Fig. 92.1 Fundus photographs of choroidal nevi with overlying (a) mild and (b) extensive drusen.


Low-Risk Choroidal Nevus


Thickness ≤2 mm, absence of subretinal fluid, orange pigment and symptoms. These lesions classically appear echodense on ultrasonography and demonstrate overlying retinal pigment epithelium (RPE) alterations such as drusen, RPE atrophy, dependent RPE trough from previous subretinal fluid, RPE hyperplasia, RPE detachment, RPE fibrous metaplasia, and RPE osseous metaplasia (▶ Fig. 92.2). Rarely, choroid nevus can produce chronic RPE damage that leads to the development of choroidal neovascular membrane (CNVM).



Multimodal imaging of a choroidal nevus. (a) Fundus photography demonstrates overlying drusen. (b) Fundus autofluorescence shows retinal pigment epithelium (RPE) atrophy centrally and mild ring-shaped


Fig. 92.2 Multimodal imaging of a choroidal nevus. (a) Fundus photography demonstrates overlying drusen. (b) Fundus autofluorescence shows retinal pigment epithelium (RPE) atrophy centrally and mild ring-shaped hyper-autofluorescence of drusen in the periphery. (c) Optical coherence tomography documents overlying drusen, RPE thinning, focal RPE detachment, retinal edema, outer retinal disorganization and retraction, and choroidal mass with compression of the choriocapillaris and loss of normal choroidal vasculature.


High-Risk Choroidal Nevus


Carries high likelihood for transformation into melanoma with features including thickness greater than 2 mm, presence of subretinal fluid, orange pigment and/or symptoms, acoustic hollowness on ultrasonography, and absence of chronic features such as drusen or surrounding halo (▶ Fig. 92.3). High-risk nevus should be evaluated by an ocular oncologist. These risk factors can be remembered with the mnemonic “To Find Small Ocular Melanoma – Using Helpful Hints Daily” representing Thickness >2 mm (T), subretinal Fluid (F), Symptoms (S) of flashes/floaters and blurred vision, Orange pigment (O), Margin less ≤3 mm from optic disc (M), Ultrasonographic Hollowness (UH), Halo absent (H), and Drusen absent (D) (Table 92.1).



High-risk choroidal “nevus” suggestive of small melanoma. (a) Fundus photograph demonstrates overlying orange pigment which is confirmed with (b) fundus autofluorescence documenting hyper-autofluoresc


Fig. 92.3 High-risk choroidal “nevus” suggestive of small melanoma. (a) Fundus photograph demonstrates overlying orange pigment which is confirmed with (b) fundus autofluorescence documenting hyper-autofluorescence of lipofuscin. (c) Optical coherence tomography documents subretinal fluid with minimal shaggy photoreceptors over the tumor apex, and choroidal mass impression of the choriocapillaris and loss of normal choroidal vasculature.



































































Table 92.1 Risk factors for choroidal nevus growth to melanoma

Mnemonic


Initial


Variable


Hazard ratio


p-Value


To


T


Thickness >2 mm


2


<0.001


Find


F


Subretinal Fluid


3


0.002


Small


S


Symptoms


Decreased vision


Flashes/floaters


2


2


0.02


0.002


Ocular


O


Orange pigment


3


<0.001


Melanoma


M


Margin distance to optic nerve ≤ 3 mm


2


0.001


Using Helpful


UH


Ultrasonographic Hollowness


3


<0.001


Hints


H


Halo absent


6


0.009


Daily


D


Drusen absent


na


na


Abbreviation: na, not available.


Source: Data from Shields CL, Furuta M, Berman EL, et al. Choroidal nevus transformation into melanoma: analysis of 2514 consecutive cases. Arch Ophthalmol 2009;127:981–987.


Halo Nevus


Central pigmented nevus with surrounding depigmented halo, most often found in young patients and believed to represent an immune response (▶ Fig. 92.4). These represent 5% of all choroidal nevi and are felt to be low risk. Halo nevus has been linked to a previous history of skin melanoma (p < 0.001) and no association with autoimmune dysfunction or vitiligo.



Halo choroidal nevus with central pigmented portion and surround yellow halo.


Fig. 92.4 Halo choroidal nevus with central pigmented portion and surround yellow halo.

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Mar 24, 2020 | Posted by in OPHTHALMOLOGY | Comments Off on Choroidal Nevus
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