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

Background: Existence of true orbital lymphangiomas has been questioned in recent years. Therefore an orbital lymphangioma was analyzed with two new s pecific markers of lymphatic endothelium. Methods: Case-report with clinico pathological, immunohistochemical, and ultrastructural findings. A 25-year- old man presented with recurrent lower lid "hematomas" and a pea-sized tumo r palpable in the left lower lid. Magnetic resonance imaging showed an infe ronasally located orbital tumor which extended to the posterior pole of the eye. The highly vascularized tumor was excised by medial orbitotomy. Resul ts: Histopathologically, the mass consisted of large, erythrocyte-filled ca vernous vessels without evidence of smooth muscle cells or pericytes surrou nding them. Numerous lymph follicles and small arterioles were scattered be tween them. Immunohistochemically, endothelial cells lining the lumina of t he cavernous vessels were partly positive for podoplanin and vascular endot helial growth factor receptor 3 (flt-4), two markers of lymphatic endotheli um. These markers did not react with endothelial cells lining the arteriole s. Ultrastructurally, cavernous vessels displayed features characteristic o f lymphatic vessels, and the smaller vessels demonstrated signs of arteriol es. Conclusion: Ultrastructural analysis and immunohistochemistry using two new markers of lymphatic endothelium suggest a lymphatic nature of large v essels in an orbital lymphangioma. A greater series of vascular orbital tum ors must be studied with these. new lymph endothelial markers to confirm th e existence of true orbital lymphangiomas and to analyze different profiles of lymph endothelial marker expression.