Histological and Immunohistochemical Findings of an Extremely Rare Multi‐Organ Metastasis of Fibrosarcoma in a Holstein Cow

A cow with a history of decreased appetite, decreased milk production and chronic mastitis was presented to Abarkuh abattoir in Yazd province 4 months post-parturition. The routine examination and systematic meat inspection revealed multi-nodular focal masses, yellowish-white in colour with firm consistency and clear borders on the surface and depth of the liver, kidney and heart, as well as in the parenchyma of both lungs. The masses showed a smooth surface without scars, bleeding and necrotic lesions. The tissue samples (1 × 1 × 1 cm³) were taken from the masses. Tissues were fixed in 10% buffered formalin and stained with haematoxylin and eosin, Masson's trichrome, and immunohistochemical staining using anti-desmin, smooth muscle antibody (SMA), vimentin and CD34 antibodies. The histopathological evaluation of the masses showed spindle-shaped cells, pleomorphic nuclei with mitotic figures and little cytoplasm. Masson's trichrome staining showed variable collagen fibres between abnormal fibroblasts. Immunohistochemical staining showed positive immunoreactivity for vimentin and negative for desmin, SMA and CD34 antibodies that are useful to distinguish this type of cancer from other spindle cell sarcomas. On the basis of the most recent literature search, this is the first report of multi-organ metastasis of fibrosarcoma in a Holstein cow in the world.