Invasive micropapillary carcinoma of the mammary gland in humans and canines: Clinicopathological, immunophenotypical and survival approaches.

Invasive micropapillary carcinoma (IMPC) is a breast cancer with a proclivity for lymph node metastasis that affects women. In canines, this carcinoma has only recently been reported and appears to have similar histological aspects as its human counterpart. Thus, the aim of the present study was to compare clinicopathological, immunohistochemical and prognostic characteristics of mammary IMPC between humans and canines. In canines, regional metastasis was more frequently observed. Histopathologically, humans and canines predominantly showed a moderate histological grade. The pure subtype and neoplastic emboli were more frequently observed in canines. Regarding immunohistochemical evaluation, most canine and human IMPCs were positive for the estrogen and progesterone receptors. A reversed pattern of epithelial membrane antigen expression and a high proliferation index predominated in both species. The mortality due to the neoplastic disease was more frequently observed in canines (94%) than in humans (4%). Thus, canine IMPCs show a larger tumor size and higher rates of the pure subtype, regional metastasis and mortality than their human counterparts and appear to provide a good spontaneous model for achieving a better understanding of the biological behavior of human IMPCs.

Canine mammary mixed tumours: a review.

Mammary mixed tumours are the most frequent neoplasias in female dogs. In humans, mixed tumours are frequently found in the salivary glands and are known as pleomorphic adenomas. In addition to their histomorphologic similarities, mixed tumours and pleomorphic adenomas have the potential to become malignant and give rise to carcinomas in mixed tumours and carcinomas ex-pleomorphic adenoma, respectively. The factors associated with malignant transformation are still poorly known in the case of canine mixed tumours. However, this form of neoplasia tends to be associated with a better prognosis than other malignant histological types. This paper discusses the main features associated with female canine mammary mixed tumours.