Corneal squamous cell carcinoma in a dog: a case report

To report a case of primary corneal squamous cell carcinoma (SCC) in an English Bulldog. In addition, immunohistochemistry of the corneal tissue mass was performed using a panel of antibodies. A prominent feature of the present case was the clinical history of chronic keratitis due to eyelid abnormalities.

No papillomavirus antigen was detected in section of normal or neoplastic corneal tissue. The corneal epithelial cells were positive for pancytokeratins AE1/AE3 and MNF116, and E-cadherin. The neoplastic cells in close proximity to the normal epithelial lining were positive for both pancytokeratins and E-cadherin with gradual loss of staining toward the center of the neoplastic mass. Rare neoplastic cells demonstrated positive staining for caspase 3 and a large number was strongly positive for GADD45 and p53.

The observed loss of the various cytokeratins, the strong p53 expression, and low numbers of caspase 3 positive cells were suggestive that a p53 mutation may have caused this primary corneal SCC. Over-expression of the tumor-suppressor gene p53 is likely to be a consequence of ultraviolet radiation exposure. Two factors, however, may have played a role in the formation of this primary corneal SCC: chronic irritation of the corneal surface (microtrauma) and exposure to UV radiation.