Pathomorphological and Immunohistochemical evaluations of pancytokeratin, vimentin and proliferating cell nuclear antigen in epithelial tumours of dogs

The present study communicates the pathomorphological findings and immunohistochemical expression of pancytokeratin (PCK), vimentin and proliferating cell nuclear antigen (PCNA) in epithelial tumours of dogs. This study included one case each of papilloma, hepatoid gland adenoma, basal cell carcinoma (BCC) and three cases of squamous cell carcinomas (SCCs). Microscopically, papilloma revealed papillary projections consisting of the different layers of stratified squamous epithelium. SCCs were further categorized as well differentiated type (2) and poorly differentiated (1). Histopathologically, well differentiated SCCs revealed islands of epithelial neoplastic cells with centrally placed keratin pearls. Poorly differentiated SCC revealed islands of neoplastic cells devoid of keratin pearls. BCC revealed solid tubular nests of neoplastic cells with peripheral palisading arrangement. Hepatoid gland adenoma showed the sheets of round to polygonal neoplastic cells with centrally placed nuclei, abundant eosinophilic cytoplasm and small basophilic reserve cells at the periphery. All cases revealed intracytoplasmic immunostaining for PCK and no staining for vimentin. In all cases, nuclear immunoreactivity for PCNA was noticed. The reactivity score for PCNA was more in SCCs and hepatoid gland adenoma as compared to papilloma and BCC. Immunostaining for PCNA was noticed in basal cells in papilloma while in well differentiated SCCs peripheral cells of epithelial pearls and a few stromal cells showed immunoreactivity for PCNA. In hepatoid gland adenoma, PCNA immunoreactivity was noticed in some hepatoid cells and a large number of reserve cells. In conclusion, besides histopathology, immunohistochemistry by using tumour markers viz. PCK expression ascertain the epithelial origin of tumour cells and PCNA for assessing the proliferation rate and prognosis of tumours.