Presumed primary ocular lymphangiosarcoma with metastasis in a miniature horse

Abstract

A 7-year-old, 153.0-kg American Miniature mare presented for evaluation of keratoconjunctivitis of the right eye (OD). A superior palpebral conjunctival mass and stromal keratitis were diagnosed. The incisional biopsy diagnosis was a presumptive corneal hemangiosarcoma. Transpalpebral enucleation was performed, and histopathologic evaluation confirmed angiosarcoma of the conjunctiva, cornea, and extraocular muscles. The horse developed progressive epistaxis and orbital swelling following surgery. A systemic workup was performed 3 months after enucleation, revealing regrowth within the orbit and marked cranial cervical lymphomegaly, suggestive of metastasis. Humane euthanasia was performed, and necropsy confirmed a locally invasive periorbital tumor with metastasis to the submandibular tissue, submandibular lymph node, and thoracic inlet. Histopathologic evaluation of necropsy specimens revealed polygonal to spindle neoplastic cells lining neoplastic vascular channels lacking erythrocytes. Immunohistochemically, the neoplastic cells labeled strongly positive for PROX-1, vimentin, CD-31, VEGF, weakly positive for factor VIII-related antigen, and negative for collagen IV. Based on the clinical, histological, and immunohistochemical features of this tumor, a primary ocular lymphangiosarcoma with metastasis was diagnosed.

Canine, feline, and equine corneal vascular neoplasia: A retrospective study (2007‐2015)

“…Because there are no reported cases of primary corneal vascular neoplasia in horses, it is difficult to accurately predict long‐term prognosis, and even for canine and feline cases, the sparsity of cases makes generalizations difficult. In reported cases of generalized “ocular angiosarcoma” with corneal involvement in horses, which includes malignant tumors of both lymphatic and blood vessel origin, some authors report no recurrence or evidence of metastatic disease up to twenty‐one months after surgery, and others describe aggressive surgery which may provide long‐term local control (up to 2 years) but eventually there is either local regrowth, and/or local and distant metastatic disease, resulting in euthanasia . Surgical removal in combination with cryotherapy or beta radiation did not successfully treat equine ocular hemangiosarcomas in one reported series of 4 cases, but the number of cases is too low for meaningful extrapolation as to the efficacy of these ancillary treatments, and this publication is over 30 years old so it is possible that therapeutic interventions have improved in this time.…”

“…Most tumors of the cornea represent extension from conjunctival, intraocular, or limbal masses. Published cases of primary corneal neoplasms in veterinary species include squamous cell carcinoma, hemangioma, hemangiosarcoma, lymphangioma, lymphangiosarcoma, papilloma, adenocarcinoma, angiokeratoma, and lymphoma . The most common primary corneal neoplasms in veterinary species are viral papilloma and squamous cell carcinoma, predominantly occurring in horses and cattle, and less often in cats and dogs …”

“…Prognosis of ocular (conjunctival, corneal, or eyelid) vascular tumors in canines, felines, and equines appears to depend on the size and extent of the lesion and ability to obtain clean margins . Treatment is via keratectomy, enucleation, or exenteration, with or without adjuvant therapies such as strontium‐90 beta (90Sr‐b) plesiotherapy, cryotherapy, CO2 laser, and/or cautery, depending on the adequacy of surgical excision and feasibility of acquiring clean margins .…”

“…Neoplasms of vascular and lymphatic origin, and even some atypical variants of squamous cell carcinoma, can be difficult to differentiate from each other with routine staining. Even with immunohistochemistry, the histiogenesis of a tumor sometimes cannot be conclusively determined . Immunohistochemical markers for endothelial cells include CD31 and factor VIII, but both benign and malignant vascular and lymphatic neoplasms are immunopositive for these two endothelial markers.…”

“…Vascular neoplasms of the cornea are rare in all species. Most vascular neoplasms involving the cornea and sclera are secondary to conjunctival, limbal, or intraocular extension . Rarely, a vascular tumor is situated centrally on cornea, with no discernible attachment or origin from the sclera, and as such, these tumors appear to be primary/spontaneous to the cornea.…”