title: Ocular angiosarcoma in the horse: morphological and immunohistochemical studies.
abstract: Angiosarcomas arising in ocular tissues of four aging horses are described. Tumors were locally invasive and eventually metastasized via the mandibular and cervical lymph nodes. Pathologically, the tumors contained well-differentiated regions, in which vascular channels were lined by pleomorphic endothelial cells, as well as poorly-differentiated regions, in which vascular channels were either rudimentary or absent. Red blood cells were scare in vascular structures formed by the tumors. Factor VIII related antigen (VIII:RAg), a blood vascular endothelial marker, was demonstrated by immunohistochemistry in tumor cells in both the well-differentiated and poorly-differentiated regions. The results suggest that ocular tumors arose in blood vascular endothelium and represented true hemangiosarcomas although a lymphatic endothelial origin could not be excluded. Immunohistochemical demonstration of VIII:RAg is a valuable adjunct to conventional stains in the diagnosis of equine vascular neoplasia.
mesh_terms: D000818:Animals; D000941:Antigens / Q000032:analysis*; D005134:Eye Neoplasms / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D005169:Factor VIII / Q000032:analysis / Q000276:immunology*; D006394:Hemangiosarcoma / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D006734:Horse Diseases / Q000276:immunology / Q000473:pathology*; D006736:Horses; D007124:Immunoenzyme Techniques; D008207:Lymphatic Metastasis; D014841:von Willebrand Factor
chemical_list: D000941:Antigens; D014841:von Willebrand Factor; D005169:Factor VIII