Intraocular Lymphangiogenesis in Malignant Melanoma of the Ciliary Body

Abstract

Purpose: : To analyze whether conjunctival lymphatic vessels can invade into the normally alymphatic eye (lymphangiogenesis) in patients with malignant melanoma of the ciliary body with and without extraocular extension.

Methods: : Ten enucleated globes with the histopathologically and immunohistochemically (S-100, HMB-45, PNL-2, Melan-A) confirmed diagnosis of a malignant melanoma of the ciliary body with extraocular extension were matched with ten globes with a ciliary body melanoma without extraocular extension regarding tumor size, cell type and melanin content. In all twenty cases immunohistochemistry was performed to identify lymphatic vessels using LYVE-1 and Podoplanin as specific markers for lymphatic vascular endothelium.

Results: : Intraocular LYVE-1+ and Podoplanin+ lymphatic vessels could be detected in seven out of ten malignant melanomas of the ciliary body with extraocular extension. Lymphatic vessels were found only at the tumor periphery directly adjacent to the sclera within the eye. Ciliary body melanomas without extrascleral extension revealed no intraocular LYVE-1+ and Podoplanin+ lymphatic vessels. Intraocular lymphatic vessels were seen significantly more often in malignant melanoma of the ciliary body with extraocular extension than in melanomas without extrascleral extension (p<0.001).

Conclusions: : Malignant melanomas of the ciliary body with extraocular extension seem to be able to attract extraocular lymphatic vessels into the normally alymphatic eye. This first evidence of secondary lymphangiogenesis into a normally alymphatic organ might explain the increased risk for lymphatic metastasis in ciliary body melanoma with extraocular extension.

Keywords: melanoma • ciliary body • pathology: human