2020–2021 BCSC Basic and Clinical Science Course™
4 Ophthalmic Pathology and Intraocular Tumors
Part II: Intraocular Tumors: Clinical Aspects
Chapter 17: Melanocytic Tumors
Melanocytoma of the Iris, Ciliary Body, and Choroid
Melanocytomas (magnocellular nevi) are rare tumors composed of characteristically large, polyhedral melanocytic cells that have small, bland nuclei and abundant cytoplasm filled with large melanin granules (see Chapter 15, Fig 15-12). Iris melanocytoma cells may seed to the anterior chamber angle, causing glaucoma. Melanocytomas of the ciliary body are usually not seen clinically because of their peripheral location. In some cases, extrascleral extension of a melanocytoma along an emissary canal appears as a darkly pigmented, fixed subconjunctival mass. Melanocytomas of the choroid appear as elevated, pigmented tumors, similar to a nevus or a melanoma. Malignant changes have been reported in some melanocytomas.
When a melanocytoma is suspected, photographic and ultrasonographic studies are appropriate. If growth is documented, biopsy should be considered to exclude melanoma.
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Shields CL, Kaliki S, Hutchinson A, et al. Iris nevus growth into melanoma: analysis of 1611 consecutive eyes: the ABCDEF guide. Ophthalmology. 2013;120(4):766–772.
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Shields JA, Shields CL, Eagle RC Jr. Melanocytoma (hyperpigmented magnocellular nevus) of the uveal tract: the 34th G. Victor Simpson lecture. Retina. 2007;27(6):730–739.
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.