Fineman_Retina (Color Atlas and Synopsis of Clinical Ophthal

270 6 Retinal and Choroidal Tumors

CHOROIDAL NEVUS C horoidal nevus is a common, benign tu mor of the posterior fundus. The lesion is typically pigmented but amelanotic variations are common as well. Although benign lesions make up the vast majority of these neoplasms, uveal melanomas occur secondary to genetic mutations within rare nevi. Epidemiology and Etiology ● Prevalence in the general population is estimated to be about 5%. The lesion occurs much more commonly in Whites. History ● Patients are usually asymptomatic and the tumor is generally discovered incidentally during routine ophthalmoscopy. ● Vision may be reduced from an extension of the associated subretinal fluid into the mac ula, an associated serous retinal detachment, or CNV arising at the edge of the nevus. These signs may be indications of malignant ● The tumor is most often slate gray or brown in color, but it may be heterogeneously pig mented or even amelanotic (pale yellow). ● Choroidal nevi are usually 1 to 10 mm in diameter, flat or minimally elevated ( < 2 mm in anteroposterior dimension). Lesions greater than 12 mm in diameter may confer malignant transformation. ● Drusen overlying the tumor are common and signify chronicity of the lesion. ● Alterations of the overlying RPE include pigment clumping and fibrous metaplasia (yellow-white plaques). ● “Orange pigment” at the level of the RPE represents aggregates of macrophages contain ing lipofuscin granules and may suggest growth or malignant transformation of the nevus. transformation into melanoma. Important Clinical Signs

● A circumferential ring of hypopigmentation (halo) is thought to represent a low-grade immune response to the tumor and thus sug gests a lower chance of malignant transforma tion ( Fig. 6-13 ). Associated Clinical Signs ● Serous detachment of the neurosensory retina or the RPE ● CNV Differential Diagnosis ● Pigmented lesion ● Choroidal melanoma ● Congenital hypertrophy of the RPE ● Combined hamartoma of the retina and the RPE ● Subretinal hemorrhage ● Amelanotic lesion ● Circumscribed choroidal hemangioma ● Diagnosis is based on characteristic ophthalmoscopic features. Fluorescein angiography or indocyanine green (ICG) angiography, although not specific for cho roidal nevus, may rule out diagnoses such as hemangioma. ● Ultrasonography typically demonstrates a choroidal lesion with low-to-medium internal reflectivity. ● Autofluorescence can identify areas of RPE loss (hypoautofluorescence) or lipofuscin activity (hyperautofluorescence). Lipofuscin is clinically seen as orange pigment and is a risk factor for tumor growth and transformation. ● OCT is valuable for imaging of retinal architecture and for detection of intraretinal and subretinal fluid that is not visible on ● Choroidal osteoma ● Choroidal metastasis ● Choroidal granuloma Diagnostic Evaluation

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