Tubulopapillary carcinoma of the mammary gland in a mare

ABSTRACT

Background: Mammary gland neoplasia are often observed in bitches and cats, rarely in cows, goats, sheep, sows, andmares. Among the neoplasia that affect mares, breast tumors are rare, as they occur more frequently in older animals. Inhorses, mammary gland tumors occur more frequently in older animals. In this species there are reports of cases describingcarcinomas and adenocarcinomas and several subtypes. Mammary neoplasms in equines tend to be locally aggressive andpromote metastases to the regional lymph nodes and other organs, including the lungs, and may cause pleural effusion.The aim objective of the present case report was to describe the clinical-pathological and immunohistochemical findingsof a tubulopapillary carcinoma of the mammary gland in mare.Case Was received a biopsy of a tumor mass of the mammary gland of a 15-year-old Quarter Horse mare. According tothe veterinarian, the mare presented an increase in volume with ulceration of the mammary gland three months before thebiopsy. Macroscopically, the mass was firm to the cut with white surface measuring 12x12 cm. The fragment was fixedin 10% formalin, routinely processed for histology, paraffin embedded, and stained with hematoxylin and eosin. Microscopically, we observed proliferation of epithelial neoplastic cells arranged in tubules and papillary projections, somewith two to three layers of cells. Neoplastic cells had oval, moderate and distinct cytoplasm. The nuclei were roundedwith dense chromatin and an apparent nucleolus. There were two figures of mitosis per field of high magnification. Proliferation of neoplastic cells invaded adjacent tissues, and in lymph vessels of the region, neoplastic cells were observedas well as inflammation in adjacent tissue. In addition, the breast fragment was submitted to the immunohistochemistrytechnique using anti-pancytokeratin and anti-vimentin antibody. In immunohistochemistry for pancytokeratin, there wasimmunoreactivity...