MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL DESCRIPTION OF A SPLENIC HAEMANGIOMA IN A CAPTIVE EUROPEAN WOLF (CANIS LUPUS)

Introduction: In wild animals, tumours are rare, particularly in wild carnivores, where few reports are available in the literature. A splenic haemangioma in a 9-year-old male captive European wolf (Canis lupus) from an Italian zoological garden is reported and histological and immunohistochemical features are described. Materials and Methods: The wolf was humanely destroyed and at necropsy examination a splenic mass of 35 25 11 cm was detected. Representative portions of the lesion were fixed in 10% neutral buffered formalin and processed routinely for histopathological evaluation (HE) and for histochemical studies (Masson’s trichrome, Perl’s Prussian blue and toluidine blue staining). Immunoreactivity to vimentin, actin, vWF, CD117, VEGF-R, VEGF-C, CD44 and MIB-1 was investigated. Results: Morphologically the tumour showed a cavernous pattern with large, dilated and massively engorged vascular spaces. Peripherally, a capillary component was present. The walls were occasionally thickened by adventitial fibrosis with scattered haemorrhages. Inflammatory cells, haemosiderin-laden macrophages and haematin deposits were observed throughout the stroma. Cells lining neoplastic lacunae were labelled for expression of vimentin and vascular markers, confirming an endothelial origin. No immunoreactivity to CD44 was noted. The average number of MIB-1 positive nuclei was 2e3/high power field and a moderate grade of mast cell infiltration was also observed.