Immunocytochemical differentiation of neoplastic and hyperplastic canine epithelial lesions in cytologic imprint preparations

The aim of the study was to test the potential use of commercially available antibodies generated against human cytokeratins in differentiating canine epithelial tumours in cytological samples. Immunocytochemical staining procedures were performed on 183 different primary epithelial canine tissues (including hyperplasia [n = 7], dysplasia [n = 3], benign [n = 54] and malignant [n = 119] neoplasia) and 20 distant metastases of 13 of the malignant tumours. ithelial tumours and their metastases stained distinctly positive with broad spectrum anti-cytokeratin AE1/AE3. Immunocytological reactions with broad spectrum anti-cytokeratin KL1 produced less reliable results. Numerous negative reactions were found, especially in columnar epithelium tumours, whereas squamous epithelium tumours were KL1-positive. In most cases specific antibodies CK7, CK8,CK14,CK18 and CK20 showed similar reaction patterns when compared to reactivity in human tissues. Immunocytological staining was found to be a reliable and valuable diagnostic technique when combined with conventional cytology and may be especially suitable for the differentiation of undifferentiated epithelial tumours and distant metastases of unknown origin.