Orbital lymphangioma with positive immunohistochemistry of lymphatic endothelial markers (vascular endothelial growth factor receptor 3 and podoplanin)

Abstract.

Background: Existence of true orbital lymphangiomas has been questioned in recent years. Therefore an orbital lymphangioma was analyzed with two new specific markers of lymphatic endothelium. Methods: Case-report with clinicopathological, immunohistochemical, and ultrastructural findings. A 25-year-old man presented with recurrent lower lid "hematomas" and a pea-sized tumor palpable in the left lower lid. Magnetic resonance imaging showed an inferonasally located orbital tumor which extended to the posterior pole of the eye. The highly vascularized tumor was excised by medial orbitotomy. Results: Histopathologically, the mass consisted of large, erythrocyte-filled cavernous vessels without evidence of smooth muscle cells or pericytes surrounding them. Numerous lymph follicles and small arterioles were scattered between them. Immunohistochemically, endothelial cells lining the lumina of the cavernous vessels were partly positive for podoplanin and vascular endothelial growth factor receptor 3 (flt-4), two markers of lymphatic endothelium. These markers did not react with endothelial cells lining the arterioles. Ultrastructurally, cavernous vessels displayed features characteristic of lymphatic vessels, and the smaller vessels demonstrated signs of arterioles. Conclusion: Ultrastructural analysis and immunohistochemistry using two new markers of lymphatic endothelium suggest a lymphatic nature of large vessels in an orbital lymphangioma. A greater series of vascular orbital tumors must be studied with these new lymph endothelial markers to confirm the existence of true orbital lymphangiomas and to analyze different profiles of lymph endothelial marker expression.