Abstract
An eight-year-old Holstein-Friesian dairy cow, which had delivered a premature calf at 6 months of gestation, was slaughtered 2 months later because of clinical signs of progressive udder swelling, reduced activity, anorexia, and agalactica. At necropsy, the udder was found to be enlarged and firm with multiple neoplastic nodules. A large amount of viscid, paste-like material occupied the whole right and part of the left front mammary gland. The supramammary and internal iliac lymph nodes too were enlarged because of the many neoplastic nodules consistent with the lesion found in the mammary gland. Microscopic study showed the mammary tumors to be characterized by a proliferation of anaplastic epithelial cells forming distinct tubular and papillary structures intermixed with many acini. The neoplastic cells were cuboidal to columnar with round or oval nuclei with single nucleoli and abundant vacuolated cytoplasm. Frequent mitotic figures were seen. In addition, eosinophilic, homogenous, and periodic acid-Schiff (PAS)-positive materials were observed in the lumens of many tubules/acini and granules/droplets within neoplastic cells. On the basis of these findings, the tumor was diagnosed as tubulopapillary mammary adenocarcinoma.
