![]() ![]() with a wide base but minimal thickening). about 5% of choroidal melanomas are diffuse (i.e.If they break through Bruch’s membrane and RPE, they can develop a mushroom (‘collar stud’) shape, which is almost pathognomic for melanoma larger choroidal melanomas are dome-shaped, with more extensive serous retinal detachment. ![]() documented growth (which requires sequential colour photography).subretinal fluid, most easily seen on OCT.clumps of orange pigment (which are hyper-autofluorescent).there is a size overlap between choroidal naevi and choroidal melanomas with the following relative frequencies:.larger size (i.e., thickness >2 mm and/or largest basal diameter (LBD) >6mm ).small choroidal melanomas are distinguished from naevi by:.the CHRPE lesion may (extremely rarely) develop low-grade adenocarcinoma on its surface.may show a narrow non-pigmented line at margins of lesion.solitary, flat, well-demarcated deeply-pigmented lesion (but may contain discrete non-pigmented areas called lacunae).drusen indicate chronicity so that their absence over a domed lesion is suspicious.atypical naevi are larger and dome-shaped, with or without drusen and/or traces of sub-retinal fluid orange pigment absent.typical naevi are small, flat and grey (though some are amelanotic), with a featureless surface and no sub-retinal fluid.outcome poor once metastasis occurs 1 year survival in 10-15%.genetic changes (chromosome 3 loss or BAP1 mutation).cell type and histopathological features.detection and treatment at earliest stage improves prognosis.life-threatening ocular malignancy (risk of metastatic disease).rare in Asians and very rare in Africans.1.3-8.6 cases per million per year in European-derived populations.90% are choroidal, 6% arise from the ciliary body and 4% from the iris.malignant transformation is extremely rare, although slight enlargement is observed in 46% of those followed up photographically for >3 years.single lesion or multiple grouped CHRPE (‘bear tracks)’.area of increased RPE hypertrophy and hyperpigmentation.benign congenital anomaly of the retinal pigment epithelium (RPE).Population studies in some ethnicities report a lower prevalence: Hispanics (2.7%), African Americans (0.6%)Ĭongenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) low malignant potential (annual rate of malignant transformation of a choroidal naevus estimated to be 1 in 8,845 in a white US population).20% within the macular region, 70% between macula and equator and 10% between equator and ora serrata area of increased choroidal pigmentation.Choroidal melanoma is a rare and life-threatening melanocytic cancer that can sometimes be difficult to distinguish from naevus. Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) has distinctive ophthalmoscopic features. The overwhelming majority are choroidal naevi, which are benign with a low risk of malignant transformation. Pigmented lesions of the choroid are a relatively common finding in the course of a routine examination of the fundus. ![]()
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