Cutaneous hemangiosarcoma in a German Shepherd dog

A mass taken from the right mandibular region of a 9-year-old female German Shepherd dog was presented for histopathological examination. Grossly, the surgically resected 7 × 5 cm mass was dark reddish, poorly circumscribed and had infiltrated the mandibular bone. The cut surface of the mass was characterized by dark reddish parts and multi focal whitish components. Microscopically, the mass revealed locally extensive necrotic lesions with infiltration of inflammatory cells, multifocal hemorrhagic lesions and numerous hemosiderin laden macrophages. Numerous neovascular structures had been formed by atypical neoplastic tumor cells – themselves composed of undifferentiated round, ovoid, and spindle shaped neoplastic cells with pleomorphic, hyperchromatic, large nucleus and scant cytoplasm. The mass also showed abundant mitotic figures, invasions of the neovascular structures by neoplastic epitheloid tumor cells and adjacent tissue, characteristic of malignancy. The neoplastic tumor cells forming neovascular structures originated from vascular endothelial cells, therefore, the tumor was diagnosed as canine cutaneous hemangiosarcoma.