Fig. 15.1
A choroidal nevus located at the inferior temporal arcade is shown in the fundus photograph (top left). En face SS-OCT shows a hyperreflective lesion, perfectly delimited from the surrounding choroid (top right). B-scan SS-OCT shows a homogeneous, hyperreflective mass, with the choriocapillaris preserved
Fig. 15.2
Several drusen over the choroidal nevus are clearly defined in the fundus and SS-OCT B-scan
15.2 Choroidal Nevus with Risk Factors for Growth
Choroidal nevus can turn into choroidal melanoma. Shields et al. [5] described eight clinical signs and features that predict malignant transformation of nevus, including thickness over 2 mm, subretinal fluid, symptoms, orange pigment, tumor proximity to optic nerve, ultrasound hollowness, halo absent, and drusen absent. These lesions show intermediate features between nevus and melanoma using SS-OCT. They have more regular internal structure than melanoma, but the choriocapillaris is not visible in most patients, whereas it is visible in nevus (Figs. 15.3 and 15.4) [1].
Fig. 15.3
Choroidal nevus with risk factors for growth at the posterior pole (top left). A patch of RPE and areas of hyper/hypo-autofluorescence is shown in the autofluorescence image (top middle). B-mode of ultrasound shows a lesion thinner than 2 mm (top right). B-scan SS-OCT presents intraretinal chronic cysts in vertical scan (bottom left) and horizontal scan (bottom right). An RPE alteration in the center of the lesion, with most of the choriocapillaris disappeared. The intrinsic features of the tumor show a hyperreflective lesion with some hyporeflective areas along the nevus, with corresponding shadowing
Fig. 15.4
Pigmented lesion located at the superior temporal arcade, with orange pigmentation and chronic subretinal fluid (top left). Autofluorescence image shows a patch of RPE atrophy and areas of hyper/hypo-autofluorescence (top middle). B-mode of ultrasound shows a small lesion thinner than 1.5 mm (top right). Outer retina alterations associated to subretinal fluid and RPE undulation are the retinal changes observed. Choriocapillaris layer is preserved along the full hyperreflective lesion, which can be clearly differentiated from the healthy choroid
15.3 Choroidal Melanoma
Imaging choroidal melanoma presents a lesion with a dome-shaped configuration with highly reflective lesion, deep optical shadowing, subretinal fluid, and shaggy photoreceptors [5, 6]. The tumor compresses the choriocapillaris in 100% of cases, resulting in an invisible choriocapillaris in SS-OCT scans [1]. Melanomas have a heterogeneous configuration on SS-OCT (Fig. 15.5), and irregularities are always present in the internal space, which differentiates from choroidal nevus that are homogeneous in their configuration (Fig. 15.6).
Fig. 15.5
Choroidal melanoma located at the posterior pole (top left). En face SS-OCT (top right) shows two areas clearly differentiated, an outer halo with a homogeneous pattern and a circular central hyperreflective area with hyporeflective lacunae. B-scan SS-OCT (bottom) presents an atrophic retina thickness with retinal pigment epithelium atrophy, no choriocapillaris preservation and a dome-shape lesion with hyper/hyporeflective areas
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