Lymphangiosarcoma in the Nictitating Membrane of a Horse

Abstract

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.Key words: Horses; lymphangiosarcoma; nictitating membrane; tumor; ultrastructural findings.Ocular tumors of vascular origin have been rarely described in horses.1,4,9,13 Such tumors include hemangiomas, hemangiosarcomas, and lymphangiosarcomas. 1,13 In cases where the cell of origin remains undetermined, they are classified as angiosarcomas. 4,9 Lymphangiosarcoma is an extremely rare tumor originating from the lymphatic endothelium.5 It occurs in various species and is most frequently described in dogs 16 and cats.6 Additionally, single cases are reported in horses 7,12 and cattle. 11 In domestic animals, lymphangiosarcomas tend to be localized in the subcutis along the ventral midline and limbs.5 Grossly, these neoplasms are poorly demarcated, soft to spongy masses, containing clear, serous fluid on cut surface.3 Histologically, lymphangiosarcomas differ little from their benign counterpart, except for their increased cellular pleomorphism. Characteristic features include clefts and channels lined with cells displaying more rounded nuclei with hyperchromatism and a slightly increased mitotic activity. 5 The underlying cause triggering the development of lymphangiosarcomas remains undetermined in most cases. However, chronic lymphedema has been shown to play an important role in humans. 15A 15-year-old Haflinger gelding showed a swelling of the left nictitating membrane of 4 weeks' duration. A biopsy of this cavernous, fluid-filled mass was taken and sent for histopathologic examination. Two weeks later, a total extirpation of the nictitating membrane was performed. Postoperatively, the horse developed a progressive periocular swelling and a sero-sanguinous nasal discharge over the following 5 months. Therefore, a second biopsy was taken. As a result of poor prognosis, the horse was euthanized but was not available for postmortem examination.For histopathologic exa...

Presumed primary ocular lymphangiosarcoma with metastasis in a miniature horse

“…A single case of lymphangiosarcoma affecting the ocular tissues has been reported in a cow . Lymphangiosarcoma is uncommonly reported in horses, and to the authors’ knowledge, only one case has been reported involving ocular tissues with no evidence of involvement of other tissues in that case . In nonocular equine cases, extensive visceral involvement has been reported .…”

“…In general, tumors of lymphatic origin are extremely uncommon in horses, with only four cases of lymphangiomas and three cases of lymphangiosarcomas reported . In the reported cases of lymphangioma, distant metastases were not documented and surgical excision was the recommended treatment; however, surgical removal was limited by size and location of the growths.…”

“…The remaining case of lymphangiosarcoma resulting in euthanasia was a mass of the nictitating membrane, which regrew following two excisions. The horse was euthanized secondary to regrowth, but systemic workup and necropsy were not performed to evaluate metastasis . Based on these cases, tumors of lymphatic origin seem to carry a poor prognosis given their infiltrative nature and potential for metastasis.…”

Corneal invasion by hemangiosarcoma in a horse

“…Equine ocular HSA is a rare malignant tumor of vascular endothelial origin 1 . LSA is another type of malignant ocular neoplasm identified in the horse, 4,6 which originates from the lymphatic system and may appear grossly and microscopically similar to HSA 5 . Histopathologic evaluation and IHC are often required to differentiate between equine ocular HSA and LSA.…”

Malignant melanoma of the third eyelid in a horse

“…Other tumours affecting the nictitans include lymphangiosarcoma (Puff et al . ), lymphangioma (Gehlen and Wohlsein ), papilloma (Lavach and Severin ; Junge et al . ), haemangiosarcoma (Sansom et al .…”