title: Immunohistochemical assessment of proliferative activity in mammary adenomyoepithelioma.
abstract: OBJECTIVE
  Two cases of adenomyoepithelioma of the breast were examined by immunohistochemistry to evaluate proliferative activity of epithelial and myoepithelial components.
  
  
  RESULTS
  The tumours showed a bicellular pattern of gland-forming epithelial cells and proliferative myoepithelial cells with clear cytoplasm. They showed foci of monotonous growth of myoepithelial cells devoid of glands with low mitotic rate (1-2/10 high-power fields) and mild cytological atypia. Immunohistochemically, the glandular cells were positive for epithelial membrane antigen, cytokeratin (KL-1 and CAM5.2) and carcinoembryonic antigen, whereas tumour cells with clear cytoplasm were reactive with muscle-specific actin (MSA), alpha smooth muscle actin, vimentin, and S100 protein but negative for desmin. Proliferative activities assessed by MIB-1 (Ki-67)/MSA positive cell index were greater in myoepithelial cells in both cases (19.2% and 17.7%) as compared to those in epithelial cells (MIB-1/CAM5.2 index: 10.2% and 9.5%).
  
  
  CONCLUSIONS
  These results might account for the previous findings that myoepithelial components predominate over the epithelial ones in an advanced stage of this tumour as well as in recurrent or metastatic lesions.
authors.affiliation: Department of Pathology, Hirosaki University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Koyama
authors.forename: H
authors.initials: H
authors.lastname: Kurotaki
authors.forename: N
authors.initials: N
authors.lastname: Yagihashi
authors.forename: S
authors.initials: S
authors.lastname: Aizawa
authors.forename: M
authors.initials: M
authors.lastname: Sugai
authors.forename: Y
authors.initials: Y
authors.lastname: Kamata
authors.forename: T
authors.initials: T
authors.lastname: Oyama
authors.forename: S
authors.initials: S
authors.lastname: Yagihashi
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D002455:Cell Division; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D019394:Ki-67 Antigen / Q000032:analysis*; D008875:Middle Aged; D009208:Myoepithelioma / Q000378:metabolism / Q000473:pathology*
chemical_list: D002272:Carcinoembryonic Antigen; D019394:Ki-67 Antigen; D007633:Keratins