Immunohistochemical expression of p63 protein and calponin in canine mammary tumours

Proposal for a Histological Staging System of Mammary Carcinomas in Dogs and Cats. Part 1: Canine Mammary Carcinomas

“…Double immunostaining to p63 and calponin is the method of choice for myoepithelial cell identification in CMCs (14, 38), whereas p63 alone is routinely used in breast cancer pathology (28). Using the same antibody to p63 as the one in the present study (clone 4A4), Łopuszynski et al were able to differentiate canine mammary carcinomas in situ from simple or complex invasive CMCs with good sensitivity, and concluded that p63 is a sensitive and more specific marker of myoepithelial cells in canine mammary tumors compared with calponin (13). The distinction between CMCs in situ and invasive CMCs seems to us of paramount importance.…”

“…One of the major changes introduced in the present histological staging system is the recognition of a specific category for mammary carcinomas in situ (stage 0), as exists in breast cancer: stage 0 breast cancers are pTis (carcinoma in situ ), N0, M0 (18). Local invasiveness is easier to detect using immunohistochemical staining of myoepithelial cells rather than on HES-stained slides, and multiple markers have been proposed for canine myoepithelial cells, including alpha smooth muscle actin, calponin, CD10, keratins 5/6 and 14, and p63 (13–15, 36–38). Double immunostaining to p63 and calponin is the method of choice for myoepithelial cell identification in CMCs (14, 38), whereas p63 alone is routinely used in breast cancer pathology (28).…”

“…Immunohistochemistry (IHC) was performed using a Benchmark XT automated instrument (Ventana Medical Systems, Roche Diagnostics) as previously described (19, 25). IHC to the myoepithelial marker p63 (mouse monoclonal, clone 4A4, abcam, dilution 1:100) was used to differentiate mammary carcinomas in situ (surrounded by a continuous layer of p63+ myoepithelial cells) from invasive mammary carcinomas (lacking a continuous layer of p63+ myoepithelial cells), as performed in human breast cancer (28), and validated in canine mammary carcinomas (13). In the absence of any metastatic carcinoma cells in the draining lymph node on HES-stained sections, IHC to pancytokeratin (mouse monoclonal, clones AE1/AE3, Dako, dilution 1:200) was performed on the draining lymph node (29), to identify potential isolated tumor cells or micrometastases.…”

“…New developments of the TNM staging system for CMCs now appear in veterinary medicine, which use histopathology and/or immunohistochemistry in addition to clinical parameters. First, immunohistochemical methods using myoepithelial cell markers enable the distinction between mammary carcinomas in situ , i.e., carcinomas restricted to the pre-existing limits of mammary lobules and ducts, from invasive mammary carcinomas, i.e., infiltrating carcinomas with the possibility of metastatic spread (13–16). This distinction is of paramount importance in human oncology, as treatment modalities and follow-up guidelines substantially differ between patients with mammary carcinomas in situ and those with invasive breast cancer (17).…”

Vitamin D receptor (VDR) expression in different molecular subtypes of canine mammary carcinoma

“…Fifty-eight (58) mammary carcinomas were eligible for inclusion in the study when a histological diagnosis of invasive mammary carcinoma was established and confirmed by an incomplete layer of p-63 positive ME cells in order to differentiate in situ from invasive carcinomas [ 34 , 55 – 57 ]. For this purpose, monoclonal mouse anti-p63 (clone 4A4), isotype IgG2 (Santa Cruz Biotechnology, Heidelberd, Germany), diluted 1:100, nuclear staining was used; this antibody was previously used in IHC studies in the dog [ 30 , 58 , 59 ]. Nineteen (19) tumours were excluded of our study because they were diagnosed as benign tumours (15) and as carcinoma in situ (4).…”