Although classification of choroidal and ciliary body melanomas according to tumor volume would be logical, no simple and reliable method has been developed for doing this. Instead, several different systems are used to categorize these melanomas by size. The Collaborative Ocular Melanoma Study (COMS) classified posterior uveal melanomas as small, medium, or large on the basis of thickness and basal diameter. The recently revised, evidencebased, and validated tumor, node, metastasis (TNM) staging system developed by the American Joint Committee on Cancer (AJCC) is the classification most often used in clinical practice. The eighth edition, like the seventh, categorizes posterior uveal melanomas as small (T1), medium (T2), large (T3), or very large (T4) according to tumor thickness and basal diameter, extension to the ciliary body, and extrascleral growth (Table 17-3). These categories are used to assign melanomas to 7 stages (I, IIA, IIB, IIIA–C, and IV) that differ in prognosis (Table 17-4).
Table 17-3 AJCC Tumor Size Categories for Ciliary Body and Choroidal Melanomasa
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.