E-cadherin Expression in Canine Mammary Carcinomas with Regional Lymph Node Metastases

Summary E‐cadherin (E‐cad) is a cell adhesion molecule known for its tumour invasion‐suppressor function. This study investigated the immunohistochemical expression of E‐cadherin in 19 cases of malignant mammary tumours of the dog and the relationship between E‐cadherin expression in primary tumours and in regional lymph node metastases. E‐cadherin expression is not always parallel in the primary tumour and in the lymph node metastasis. One year follow‐up was available in 12 of 19 cases. Three different patterns of expression were revealed in the lymph node metastases compared with the primary tumour: downregulation when the protein expression was weaker in the metastasis than in the primary tumour; upregulation when E‐cadherin was stronger in the lymph node than in the primary tumour, and a similarly intense expression when it was equal in the metastasis and in the tumour. The lymph node pattern revealed a prevalent upregulation or downregulation with respect to the primary tumour, whereas a similar expression of E‐cadherin was encountered in less than 50% of cases.