Immunohistochemistry with keratin, vimentin, desmin, and α‐smooth muscle actin monoclonal antibodies in canine mammary gland: Benign mammary tumours and duct ectasias

Summary

Duct ectasias (n=2) and different types of benign canine mammary tumours (n=19) were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types (K), α‐smooth muscle actin, vimentin, and desmin. In the duct ectasias and in most tumours the epithelial structures revealed an inner and outer cell layer. The inner cell layer was characterized by labelling with K 7, 8, 18, 19 and mostly also with K 4 and/or K 10 MoAbs. The outer cell layer was almost invariably labelled by K 14, K 14 and 17, and a‐smooth muscle actin MoAbs. The labelling patterns of both duct ectasias and tumours corresponded largely to the patterns observed in normal mammary gland tissue, although a more distinct heterogeneity was seen. Tumours histomorphologically assumed to be of a myoepithelial origin did not show immunohistochemical features of myoepithelial cells. The myoepithelial nature of the vast majority of spindle‐shaped cells present in the adenomas of the complex type and in the fibroadenomas of the benign mixed type could not be confirmed immunohistochemically. These cells, however, unequivocally expressed vimentin, suggesting proliferation of stromal cells in these tumours, which in the fibroadenomas of the benign mixed type may show metaplasia to bone or cartilage.

In the duct ectasias and in some tumours, a fraction of elongated stromal cells, probably representing myofibroblasts, was labelled with the α‐smooth muscle actin MoAb.

Notes

Department of Pathology, Faculty of Veterinary Medicine, University of Utrecht, Utrecht, the Netherlands

present address: Animal Health Service in the Southern Netherlands, P.O. Box 4, 5280 AA Boxtel, the Netherlands

Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, University of Utrecht, Utrecht, the Netherlands

The Netherlands Cancer Institute, Division of Tumour Biology, Amsterdam, the Netherlands

Department of Molecular Cell Biology & Genetics, University of Limburg, Maastricht, the Netherlands

Additional information

Notes on contributors

J.H. Vos

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