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including radiation (Mosunic et al., 2004; Plummer et al., 2007), laser photoablation (Clode et al., 2012; Michau et al., 2012), topical chemotherapy with mitomycin-C (Malalana et al., 2010; Rayner & Van Zyl, 2006) or 5-fluorouracil (Offer et al., 2022) and/or cryotherapy (Surjan et al., 2014). In some cases, enucleation or exenteration is necessary to achieve complete resection (Montgomery, 2014). Recurrence rates following treatment vary in the literature from 11.9% to 66.7% (Dugan et al., 1991b; King et al., 1991; Mosunic et al., 2004; Plummer et al., 2007; Schwink, 1987). Corneal vascular tumours (haemangioma and
haemangiosarcoma) are rare, but a few reports in equine patients exist. Most of them extend into the cornea from lesions on the limbus (Pinn et al., 2011; Scherrer et al., 2018), but some primary corneal haemangiosarcomas have been described (Shank et al., 2019). The number of cases reported is too small to draw any conclusions, but no breed, age or sex appears overrepresented. Interestingly, some of these tumours displayed solar elastosis on histopathological examination, suggesting ultraviolet light-induced damage (Scherrer et al., 2018). Complete surgical excision via keratectomy/conjunctivectomy, potentially followed by treatment with topical mitomycin-C, may be associated with resolution, although at least one horse had to be euthanised due to recurrence (Pinn et al., 2011; Scherrer et al., 2018). A case of primary corneal malignant melanoma has
been described in a 13-year-old Missouri Fox trotter gelding (Strauss et al., 2019). The horse in this report presented with two irregular, pale pink, superficial corneal masses in association with faint areas of pigmentation throughout the entire cornea. The masses were removed via superficial keratectomy, followed by treatment with topical mitomycin-C and strontium-90 beta irradiation. No recurrence was noted over the follow-up period (10 months). There is also a single case report of a mast cell tumour
invading the cornea in a 3-year-old Marwari mare (Halse et al., 2014). In this case, the tumour originated in the limbus behind the dorsal edge of the third eyelid and extended into the adjacent ventromedial cornea. The mass had an irregular, fleshy, red appearance and was removed via keratectomy. No recurrence was noted at last follow-up (32 months). Finally, a case of pleomorphic corneal sarcoma resembling
malignant peripheral nerve sheath tumour invading the cornea has been described in a 14-year-old Haflinger (Kappe et al., 2009). In this case, the affected eye was enucleated with no further follow-up information available.
Author’s declaration of interests No conflicts of interest have been declared.
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