EN
The aim of the study was an attempt to elucidate canine haemangiopericytoma histogenesis based on immunohistochemical analysis using a range of commercially available antibodies. Seventeen canine haemangiopericytomas were examined. Histological analysis revealed the presence of spindle cells arranged in a circular pattern around capillaries (.fingerprint. pattern) or interlacing bundles. Fingerprint patterns were the distinguishing feature in all examined haemangiopericytomas. Immunohistochemical analysis revealed positive expressions of vimentin, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), S-100 protein (S-100) and smooth muscle actin (a-SMA). Negative reactions in tumor cells were observed for cytokeratin (CK), desmin (DES), epithelial membrane antigen (EMA) and VIII-related antigen factor (FVIII). Positive expressions of neuronal markers may not necessarily reflect the neural origin of tumors due to their low specificity. Immunoreactivity for α-SMA and DES negativity may suggest the presence of vascular smooth muscle cells or cells of pericytic origin. Moreover, the α-SMA antibody may be useful for a differential diagnosis of canine haemangiopericytomas.