title: Lymphangiosarcoma in the nictitating membrane of a horse.
abstract: A 15-year-old Haflinger gelding presented with a mass in the left nictitating membrane. Two biopsies and the excised nictitating membrane were taken at different time points as a result of reoccurrence of the mass and submitted for histopathologic evaluation. The horse was euthanized as a result of poor prognosis following the reoccurrence of the mass after surgical removal. Histologically, the mass consisted of dilated, thin-walled vascular clefts and channels, lined by flattened to cuboidal endothelial cells with moderate cellular pleomorphism. There was up to 1 mitotic figure per high power field. The channels were empty or contained few erythrocytes. In the collagen-rich stroma, few lymphocytes, focal follicular lymphoid aggregations, and marked lymphangiectasia were observed. Immunohistochemically, the neoplastic cells stained positive for vimentin and partially positive for factor VIII-related antigen. Ultrastructural analysis revealed discontinuous endothelial lining vascular channels that partially lacked a basal membrane. Based on the histopathologic, immunohistochemical, and ultrastructural features lymphangiosarcoma was diagnosed.
authors.affiliation: Department of Pathology, University of Veterinary Medicine Hannover, Bünteweg 17, D-30559 Hannover, Germany. Christina.Puff@tiho-hannover.de
authors.forename: Christina
authors.initials: C
authors.lastname: Puff
authors.forename: Vanessa
authors.initials: V
authors.lastname: Herder
authors.forename: Andrea
authors.initials: A
authors.lastname: Philipp
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumgärtner
mesh_terms: D000818:Animals; D001706:Biopsy / Q000662:veterinary; D005134:Eye Neoplasms / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D017809:Fatal Outcome; D006651:Histocytochemistry / Q000662:veterinary; D006734:Horse Diseases / Q000473:pathology* / Q000601:surgery; D006736:Horses; D008204:Lymphangiosarcoma / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D008297:Male; D009541:Nictitating Membrane / Q000473:pathology* / Q000601:surgery