Ciliary Body and Choroidal Nevi
Nevi of the ciliary body are rare, mostly small, and often first identified in histologic examination of globes enucleated for other reasons. Choroidal nevi may occur in up to 8% of the population (Fig 17-4; see p. 310). Similar to iris nevi, in most cases they cause no symptoms and are recognized incidentally on routine ophthalmic examination. Ophthalmoscopically, the typical choroidal nevus appears as a flat or minimally elevated, pigmented (gray to brown) choroidal lesion with soft margins (see Fig 17-4A–E). Some nevi are amelanotic (see Fig 17-4F).
Choroidal nevi are often associated with overlying retinal pigment epithelium (RPE) disturbance and drusen (see Fig 17-4A, D). These features are characteristic of a long-standing, quiescent lesion. A minority develop atypical features such as localized serous retinal detachment over and around the nevus (see the section Melanoma of the Choroid and Ciliary Body), surface lipofuscin (see Fig 17-4E, F), or choroidal neovascular membranes. These atypical nevi may result in reduced vision, metamorphopsia, and visual field defects. Although these clinical features can be seen in the context of a benign lesion, they should also raise suspicion for malignant transformation, and careful follow-up for progression and lesion growth is indicated.
Figure 17-1 Benign iris melanocytic lesions, clinical appearance. A, Iris freckles are flat and often multiple. B–D, Iris nevi have a variable appearance and may be flat (B, C) or nodular (D). They may cause ectropion uveae (B). C–H, The slit-lamp (C, D), gonioscopic (E, F), and ultrasound biomicroscopic (UBM) (G, H) appearances of 2 long-standing iris nevi are shown. The lesion shown in parts C, E, and G is flat and diffuse and has remained stable for 15 years. The lesion shown in parts D, F, and H is nodular and has remained stable for 20 years.
(Parts A and C–H courtesy of Alison Skalet, MD, PhD; part B courtesy of Tero Kivelä, MD.)
Figure 17-2 Iris melanoma, clinical appearance. A, The lesion can be amelanotic with visible intrinsic vascularity. B, Alternatively, it may be densely pigmented, obscuring any blood vessels (note the dispersed pigment on the iris stroma). C–H, The slit-lamp (C, D), gonioscopic (E, F), and UBM (G, H) appearances of 2 iris melanomas are shown. The melanoma shown in parts C, E, and G is a small nodular tumor involving the anterior chamber angle; fine-needle aspiration biopsy revealed a melanoma composed of mainly epithelioid cells. The tumor shown in parts D, F, and H is a large amelanotic melanoma with prominent vascularity. Note the flat pigmented portion of the tumor (arrowheads in part F) along the edges of the mass surrounding the amelanotic portion.
(Part A courtesy of Tero Kivelä, MD; parts B–H courtesy of Alison Skalet, MD, PhD.)
Table 17-1 Differential Diagnosis of Iris Melanoma
Figure 17-3 Differential diagnosis of iris melanoma. A, A pigment epithelial cyst (asterisk) can bow the iris forward focally. The cyst is visible after dilation. B, Multiple Lisch nodules in neurofibromatosis. Lisch nodules are melanocytic hamartomas that are typically tan to golden brown. C, Metastasis from a pulmonary carcinoma seen as an amelanotic mass on the temporal half of the iris and inside the pupil. The tumor distorts the pupil shape. D, Congenital ocular melanocytosis can cause a diffuse iris nevus but is associated with pigmented patches on the episclera and sclera (arrows). Note the deeply pigmented, velvety stromal thickening in the iris.
(Parts A and B courtesy of Tero Kivelä, MD; parts C and D courtesy of Alison Skalet, MD, PhD.)
In the choroid, congenital ocular melanocytosis is similar in appearance to a diffuse nevus (see Fig 17-4G). This condition increases the lifetime risk for ciliary body and choroidal melanoma (1 in 400).
Findings on fluorescein angiography are not usually helpful for diagnosis; choroidal nevi may demonstrate either hypofluorescence or hyperfluorescence. Nevi are distinguished from choroidal melanomas and other pigmented fundus lesions by clinical evaluation and multimodal imaging, as described in the section Melanoma of the Choroid and Ciliary Body.
The management of choroidal nevi includes photographic documentation of all lesions; ultrasonographic measurement of lesions thicker than 1 mm; and lifelong, periodic reassessment for signs of growth or change consistent with transformation into choroidal melanoma (Fig 17-5). OCT can be helpful in excluding the presence of subclinical subretinal fluid.
Benign nevi may increase in diameter in the absence of malignant transformation. In a long-term study of choroidal nevi, nevi enlarged a median of 1 mm overall, but the median yearly rate of enlargement was less than 0.1 mm, and none of the enlarging nevi developed new orange pigment or subretinal fluid. Frequency of enlargement was reported to be 54% in patients younger than 40 years and 19% in patients older than 60 years. If rapid or more extensive enlargement is documented, especially in patients older than 40 years, malignant transformation should be suspected (Fig 17-6).
Mashayekhi A, Siu S, Shields CL, Shields JA. Slow enlargement of choroidal nevi: a long-term follow-up study. Ophthalmology. 2011;118(2):382–388.
Shields CL, Furuta M, Berman EL, et al. Choroidal nevus transformation into melanoma: analysis of 2514 consecutive cases. Arch Ophthalmol. 2009;127(8):981–987.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.