Immunohistochemistry studies on bovine squamous cell carcinoma morphological characterization of epidermal cell proliferation and differentiation markers and characterization of cytokeratins

Bovine Ocular Squamous Cell Carcinoma (OSCC) is a general designation for a group of primary neoplasias of keratinocytes arising from ocular tissues, especially the lids and particularly the third eye lid. OSCC has been diagnosed all over the world with high prevalence, being the most common bovine tumour and the one causing the most significant economic losses (Hamir & Parry, 1980; Dennis et al., 1985, Heeney & Valli, 1985; Wilcock, 1993). In Portugal, the frequency of these tumours is particularly high in the Azores, where in S. Miguel Island a large number of cattle affected with OSCC is rejected for consumption at slaughter. OSCC is the second most frequent neoplasia after urinary bladder tumours, representing 21% of all cases of rejection due to neoplasia (Pinto et al, 1996). Several reasons have been advanced to explain this situation namely the fact that animals stay in pasture all year around, with a prolonged exposition to day light and benefiting from few shelters. The ingestion of toxic plants present the pasture could also give rise to photosensitazation problems, either primary or due to hepatic toxicity, that could generate predisposing conditions to the development of OSCC