Restricted Access

You must be logged in to view this content.

Differentiate choroidal naevii from melanoma

$currentPage/@nodeName

Suzanne Efron
BSc(Hons) MPhil GradCertOcTher
Mermaid Beach (Gold Coast) QLD

CASE REPORT

Optometrists frequently encounter patients with choroidal naevii and are called on to distinguish them from the much more sinister choroidal melanoma. Estimates of the prevalence of choroidal naevii vary between 4.6 per cent and 7.9 per cent in a white US population.1 The Blue Mountains Eye Study gave an incidence of 6.5 per cent in a white Australian population.2

There is a large overlap in the size of naevii and melanoma at initial presentation, both in terms of the largest linear basal diameter and the thickness of the lesion.3 For smaller lesions without other distinguishing features, it is reasonable to monitor them. With easier access to imaging devices, it is possible for optometrists to undertake this monitoring process with greater confidence.

The annual rate of malignant transformation of choroidal naevii has been estimated to be one in 8,845.1 Distinguishing features often associated with malignant transformation include the shape, colour, size and thickness of the tumour.

The presence of symptoms, surface clumps of orange pigment (lipofuscin), surface drusen, associated serous sub-retinal fluid and invasive clinical features—such as focal eruption through Bruch’s membrane, retinal invasion and optic disc invasion—can all be indicators of transformation to melanoma. Another important indicator is a documented increase in size, which imparts an almost eight-fold greater risk for metastasis.4 However, slow growth of 0.5 mm over many years or decades may simply reflect the natural progression of a benign choroidal naevus.5

Initial presentation

In March 2011, a 63-year-old male presented for a routine eye examination. Fundus photographs revealed the presence of two presumed choroidal naevii in his left eye (Figure 1). These were small with no distinguishing features and were monitored every six months. By January 2014, enlargement of the superotemporal lesion was evident (Figure 2).

Ph -184-Figures -1-and -2_OL
Figure 1. Retinal photograph, 2011. Figure 2. Retinal photograph, 2014

The patient was referred for an ophthalmological opinion. Both lesions were flat on B-scan ultrasound. At this stage, it was considered that the risks for transformation were low and further monitoring was suggested.

The patient next presented in February 2015. On this occasion images were obtained with the Optomap wide-field imaging device (Figure 3A). This showed that the superotemporal lesion had further increased in size, now extending beyond the superior arcade vessel.

Ph -184-Figures -3_OL

Figure 3. Optomap ultra-wide field retinal image, 2015: (A) composite view (B) red channel view (C) green channel view

Separate channels

One feature of the Optomap is that it is possible to split the composite image into separate red and green laser channels. The red channel images the choroidal layer, which is where the lesions are seen (Figure 3B). The green channel images the retinal layer. Typically, in malignant lesions there is a ‘bright’ appearance in the retinal layer6 but fortunately for this patient there is no extension of either lesion into the retinal layer (Figure 3C).

The patient has been referred back for further investigation and may require transpupillary thermotherapy treatment as a precaution. This uses infrared light to heat and eliminate the tumour. It is most effective for small tumours as it may not fully penetrate the deeper parts of thicker melanomas, where plaque radiotherapy or even enucleation are indicated because of the risk of metastasis.

 

  1. Singh AD, Kalyani P, Topham A. Estimating the risk of malignant transformation of a choroidal nevus. Ophthalmology 2005; 112: 10: 1784-1789.
  2. Sumich P, Mitchell P, Wang JJ. Choroidal nevi in a white population: the Blue Mountains Eye Study. Arch Ophthalmol 1998; 116: 5: 645-650.
  3. Augsburger JJ, Corrêa ZM, Trichopoulos N, Shaikh A. Size overlap between benign melanocytic choroidal nevi and choroidal malignant melanomas. Invest Ophthalmol Vis Sci 2008; 49: 7: 2823-2828. doi: 10.1167/iovs.07-1603.
  4. Shields CL, Shields JA, Kiratli H, De Potter P, Cater JR. Risk factors for growth and metastasis of small choroidal melanocytic lesions. Ophthalmology 1995; 102: 9: 1351-1361.
  5. Shields CL, Furuta M, Berman EL, Zahler JD, Hoberman DM, Dinh DH, Mashayekhi A, Shields JA. Choroidal nevus transformation into melanoma: analysis of 2514 consecutive cases. Arch Ophthalmol 2009; 127: 8: 981-987. doi: 10.1001/archophthalmol. 2009. 151.
  6. Kernt M, Schaller UC, Stumpf C, Ulbig MW, Kampik A, Neubauer AS. Choroidal pigmented lesions imaged by ultra-wide-field scanning laser ophthalmoscopy with two laser wavelengths (Optomap). Clin Ophthalmol 2010; 4: 829-836.


Like us on Facebook




Subscribe to our News RSS Feed

Latest Tweets




Recent Comments