纤维肉瘤是一种起源于胶原基质中的恶性成纤维细胞的间叶肿瘤，通常出现在女性生殖器官中，很少涉及皮肤。一头5岁的黑白奶牛被送来，右耳基底部有一块凸起的肿块。经过外观检查，该肿块大小约为13.00×10.00×7.00厘米。最终选择完全手术切除。肿块被包裹着，长梭形至多角形的肿瘤细胞扩展了真皮。这些细胞呈交织状排列。有丝分裂图像很少见。马松三色染色显示胶原蛋白呈阳性和蓝色染色。免疫组化检查中，Vimentin呈均匀阳性，Desmin、SMA和GFAP呈阴性。基于组织病理学特征，诊断为良性纤维肉瘤。手术切除是该肿瘤的首选治疗方法。在该例中，手术切除也成功完成了，手术程序后4个月未观察到肿块的新生长。据我们所知，这是首次报告黑白奶牛患有良性纤维肉瘤。©2023年作者。由John Wiley＆Sons Ltd.出版的《兽医医学与科学》发表。

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.© 2023 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.