Expression of Myoepithelial Markers in Mammary Carcinomas of 119 Pet Rabbits
Institute of Veterinary Pathology, University of Leipzig, 04109 Leipzig, Germany
Private consultant, full stack developer, Leipzig, Germany
Veterinary Practice Ralf Bischoff, 49328 Melle-Markendorf, Germany
Laboklin GmbH & Co. KG, Laboratory for clinical diagnostics, 97688 Bad Kissingen, Germany
Targos Molecular Pathology GmbH, 34119 Kassel, Germany
Author to whom correspondence should be addressed.
Received: 9 September 2019 / Revised: 23 September 2019 / Accepted: 26 September 2019 / Published: 28 September 2019
Mammary cancer is a serious health issue in pet rabbits; prognostic factors are unknown. In a normal mammary gland, glandular secretory cells are surrounded by a single continuous layer of myoepithelial cells. In non-invasive mammary carcinomas, tumor cells are delineated by an intact myoepithelial layer, which is gradually lost to invasive carcinomas. The main aim of this study was to determine in rabbit mammary carcinomas (n = 119) the expression of myoepithelial markers that have prognostic significance in human cancer. Results show that all cases contained some retained myoepithelial cells. In 93% of the tumors, neoplastic cells expressed the myoepithelial marker calponin. There was a statistically significant association between higher percentages of calponin-containing cancer cells and histological features indicative of a better tumor differentiation, i.e., a lower proliferation of tumor cells, an increased percentage of tubular growth within the tumor, and a lower tumor grade, respectively. These results suggest that rabbit mammary carcinomas develop from progression of non-invasive cancer forms, and that calponin expression in cancer cells likely represents a favorable prognostic factor. The latter hypothesis has to be confirmed in long-term follow-up studies.