Conway confirmed most clinicians’ impressions that choroidal naevi are common at around 5–10% in Caucasians, but less common in Asian and African eyes, while noting that they became obvious in adolescence and early adulthood. He went on to describe benign choroidal naevi as flat or nearly so (<2 mm thick), stable in size, and usually slate grey or mid-brown, but sometimes uncoloured. He also said that over time they show signs of degeneration, including drusen, which suggests inactivity.The risk of one developing into a melanoma was put at 1:5,000 per annum. However, Conway gave a 3% ‘conversion’ rate for the second category, suspicious choroidal naevi. Suspicions are raised by larger size and increased thickness (>2 mm), growth and symptoms relatable to a lesion, including scotoma, photopsia, Amsler grid disturbance, and less likely, a field defect.Other indicators are sub-retinal fluid, orange pigmentation or prominent autofluorescence, acoustic hollowness (B-Scan), posterior margin touching the optic nerve, and a lack of signs of chronicity.While ultra-wide funduscopy and photography through a well-dilated pupil are useful, Conway said it was possible to miss peripheral lesions. Where reasonable doubt exists, a 3–6 month re-examination was recommended, as changes are likely within that time frame. Melanoma treatments include: plaque brachytherapy, other radiotherapy, or PDT laser. While ultrasound is still a useful investigation technique, OCT is now used widely. Non-suspicious moles tend to show thinning of the outer layers of the retina, whereas suspicious moles tend to have sub-retinal fluid and little or no outer layer thinning.{{image3-a:r-w:300}}Accumulation of the orange-brown pigment lipofuscin in naevi is regarded as a risk factor in the conversion to melanoma. Autofluorescence of lipofuscin using special filters and detectors is a useful diagnostic test of such an accumulation. Other tests include fluorescein, which is generally used infrequently, and ICG (more useful in polypoidal changes) angiography in the search of leaks, fluid accumulations over the mole, and abnormal blood vessels.Regardless, none of those investigations are ‘diagnostic’, and in most cases, all that is required is a good quality photograph that must include the whole lesion. Repeat images should be taken every 1–2 years. Although there is a low association with UV light, Conway also recommended patients wear dark, wrap-around sunglasses and a brimmed hat. Advanced melanomas are neither treatable nor preventable, and as a precaution, he suggested that immediate family mbers of melanoma cases also be examined.Conway chose conjunctival melanomas and conjunctival squamous cell carcinomas (conjunctival SCCs) as the topics for his frontier lecture. The latter, together with corneal intraepithelial neoplasia (CIN) constitutes the group referred to as OSSNs (ocular surface squamous neoplasias). OSSNs have a yearly incidence of 1–3.5 cases per 100,000 of the population.Risk factors include sun exposure (especially UVB), light-coloured skin, smoking, radiation, and toxins – especially arsenic and polycyclic hydrocarbons. Because of those risk factors, including occupation exposure, the sufferers tend to be older, working-class males.The OSSNs have been associated recently with HPV and in developing countries, with HIV. In Sydney, there is a tendency towards patients being younger because of recreational sun exposure. The aetiology of the conditions appears to involve UV, p16/HPV, and some form of immunosuppression/immunocompromise, as well as interactions between all three. Age is also a factor.About 20% of conjunctival melanomas are amelanotic, which can mean their true nature is not as expected, for example pigmented. The gold standard treatment for SCCs is excisional resection using a no-touch technique, followed by freeze-thaw adjuvant cryotherapy to the conjunctival edge and base. Without supplental therapy, a 10–30% recurrence rate can be expected, while a no-touch excision is required to rove the risk of spreading tumour cells locally.As OSSN is conceptually an all-encompassing term for conditions ranging from aggressive, invasive SCC to benign papillomas, Conway regards it as ‘imprecise’ for use in pathology reports or when planning managent strategies. For those reasons, he prefers CIN/SCC.Biopsies and subsequent histology assays are required for assessment and treatment planning, with the former also required to gain an understanding of the depth of lesions. Topical adjuvant chotherapy includes mitomycin C (MMC). However, MMC has inflammation, pain, and scarring of the lacrimal syst as possible side effects. Despite the possibility of corneal melts, 5-FU and interferon a-2b are used in cases where the radial margins are involved, and radiotherapy and further surgery are used when the deep margins are involved.To be effective, up to four months of compliant medication usage can be required, and side-effects can be detected up to one month after the cessation of treatment.Invasive conjunctival carcinomas have two sub-types, p53 and HPV, and can be treated with MMC, 5-FU, interferon a-2b, radiotherapy, and plaque brachytherapy – especially for deep lesions. Unlike uveal melanoma, up to 40% of conjunctival melanomas have BRAF mutations, although other mutations similar to those affecting the skin can also be involved.Even though therapies targeting specific mutations, as determined by mutation tests, can result in complete regression initially, most still have microscopic disease and will recur. MMC treatment is useful in intraepithelial disease and when surgical resection is impossible, but, treatment for more than six weeks is required.Invasive (e.g. into the sclera) disease requires plaque brachytherapy. Conway finished by promoting the use of registries such as the SSI series, especially in the case of rare diseases for which adequate randomised clinical trials are impossible because of low patient numbers.
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Professor MAX CONWAY is Associate Professor in The Discipline of Ophthalmology at The Save Sight Institute, The University of Sydney and practices at Sydney Eye Hospital and St Vincent’s Hospitals, Sydney. He is currently Chair of the RANZCO Ophthalmic Pathology Board of Examiners, and Co-convener of the Scientific Programme Committee for the 2018 World Ophthalmology Congress. |
