Histological observations on aural fibrosarcoma in a Holstein cow

Fibrosarcomas occur as a mesenchymal tumour of malignant fibroblasts in a collagen background and are usually found in the female genital organs and rarely involve the skin. A 5‐year‐old female Holstein cow with a raised mass at the base of right ear was referred. On gross examination, the mass was approximately 13.00 × 10.00 × 7.00 cm in size. Finally, complete surgical removal was selected. The mass was encapsulated and the dermis was expanded by spindle‐shaped to polygonal neoplastic cells. These cells were arranged in interwoven pattern. Mitotic figures were infrequent. Masson's trichrome demonstrated the positive and blue staining of collagen. Immunohistochemically, the sections were uniformly positive for Vimentin and negative for Desmin, SMA and GFAP. A well‐differentiated fibrosarcoma was diagnosed based on histopathological features. Surgical excision is the treatment of choice for this neoplasm. In the present case, surgery was also performed successfully and no new growth of the mass was observed 4 months following the surgical procedures. To our knowledge, this is the first report of well‐differentiated fibrosarcoma in a Holstein cow.