Intraocular lymphatics in ciliary body melanomas with extraocular extension: functional for lymphatic spread?

To assess the functional significance of intraocular tumor-associated lymphatic vessels in ciliary body melanomas with extraocular extension.

Twelve consecutive patients enucleated for a malignant melanoma of the ciliary body with extraocular extension and immunohistochemical presence of intraocular LYVE-1-positive and podoplanin-positive lymphatic vessels were examined for proliferation status and tumor invasion into tumor-associated lymphatics. Proliferating lymphatic vessels were identified using LYVE-1 and podoplanin as specific lymphatic endothelial markers and Ki-67 as the proliferation marker. Tumor invasion into lymphatic vessels was assessed using Melan-A as the melanoma marker. Kaplan-Meier analyses of survival and metastasis were performed.

Intraocular proliferating lymphatic vessels were detected in all 12 ciliary body melanomas with extraocular extension. The ratio of proliferating lymphatics was significantly higher in the intraocular vs extraocular tumor compartment (P < .001). Extraocular lymphatic invasion by tumor cells was observed in 5 patients (42%), intraocular lymphatic invasion in 4 (33%), and synchronous intraocular and extraocular lymphatic invasion in 3 (25%). Detection of melanoma cells in intraocular and extraocular lymphatic vessels was significantly associated with higher risks of lymphatic spread (P < .001) and lower metastasis-free survival rates (P = .03).

Intraocular tumor-associated lymphatic vessels contain proliferating endothelial cells and can be invaded by cancer cells in ciliary body melanomas with extraocular extension. Lymphatic invasion by tumor cells seems to be associated with an increased risk of lymphatic spread and mortality in these affected patients.