title: Canine mammary mixed tumours: immunohistochemical expressions of EGFR and HER-2.
abstract: BACKGROUND
  Benign mixed tumours (BMTs) are frequently found in the mammary glands of female dogs, but the factors determining malignant transformation in these tumours are unknown.
  
  
  OBJECTIVE
  To evaluate the expression of the oncoproteins, human epidermal growth factor receptor 2 (HER-2) and epidermal growth factor receptor (EGFR), in 46 carcinomas in BMTs (CBMTs) and to verify their possible association with the malignancy of the tumours.
  
  
  METHODS
  Immunohistochemical expression was analysed in benign and malignant components separately, and then compared with 74 cases of BMTs.
  
  
  RESULTS
  Among the CBMTs, positivity for HER-2 was found in the benign histological component of 4.3% (2/46), in the malignant epithelial non-invasive component of 14.8% (4/27) and in the malignant invasive epithelial component of 13.6% (6/44) of cases. Two of the 24 (8.3%) BMTs were positive for HER-2. There was no relationship between HER-2 and the tumour components. There was no significant difference between BMTs and CBMTs. Positivity for EGFR was found in the benign component of 17.4% (8/46) of the CBMTs, in the malignant epithelial non-invasive component of 40.7% (11/27%) and in the invasive epithelial malignant component of 45.4% (20/44). EGFR positivity was significantly associated with the invasive component of CBMTs.
  
  
  CONCLUSIONS
  EGFR may contribute to malignant epithelial transformation of BMTs. In contrast, HER-2 overexpression may not be associated with the acquisition of a malignant epithelial phenotype.
authors.affiliation: University of Rio Doce Valley, Governador Valadares, Minas Gerais, BrazilLaboratory of Comparative Pathology, Department of General Pathology, Institute of Biological Science, Federal University of Minas Gerais, Brazil Laboratory of Comparative Pathology, Department of General Pathology, Institute of Biological Science, Federal University of Minas Gerais, 486 31270-901 Belo Horizonte Minas Gerais, Brazil; cassalig@icb.ufmg.br.
authors.forename: A C
authors.initials: AC
authors.lastname: Bertagnolli
authors.forename: E
authors.initials: E
authors.lastname: Ferreira
authors.forename: E J
authors.initials: EJ
authors.lastname: Dias
authors.forename: G D
authors.initials: GD
authors.lastname: Cassali
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D004283:Dog Diseases / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D004815:Epidermal Growth Factor / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000662:veterinary; D018198:Mixed Tumor, Malignant / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*
chemical_list: D004815:Epidermal Growth Factor; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
keywords: dogs; immunohistochemistry; mammary gland; neoplasm; oncogene