title: Characteristic morphology of invasive micropapillary carcinoma of the breast: an immunohistochemical analysis.
abstract: OBJECTIVE
  Invasive micropapillary carcinoma of the breast is a distinct variant of breast cancer. In the present study, we analyzed potential immunophenotypic changes in invasive micropapillary carcinoma.
  
  
  METHODS
  Specimens from 15 patients with invasive micropapillary carcinoma were analyzed using clinicopathological and immunohistochemical methods. We also examined the relationship between clinicopathological factors using the Ki-67 labeling index.
  
  
  RESULTS
  Immunohistochemical staining for cytoplasmic p63 expression was seen in four (27%) tumors, and p63 nuclear expression was also observed in four (27%) tumors. Involucrin and 34betaE12 were expressed in the invasive micropapillary carcinoma component of nine (60%) and four (27%) tumors, respectively. Cytokeratin 5/6 was expressed in three (20%) tumors and cytokeratin 14 staining was negative in all tumors. In one tumor (case 3), vimentin, epithelial membrane antigen and cytokeratin 8/18 were co-expressed. Four tumors (27%) were negative for the estrogen receptor/progesterone receptor/HER2. However, 11 out of 15 (73%) tumors were positive for the estrogen receptor. The Ki-67 labeling index was significantly higher in cases with p63 tumor expression than in those without (P < 0.0001), and also higher in cases with lymph node metastasis than in cases without (P = 0.0029).
  
  
  CONCLUSIONS
  Nuclear expression of p63, involucrin and 34betaE12 were detected indicating squamous differentiation. Cytoplasmic p63 expression was also identified. The fact that the Ki-67 labeling index was significantly higher in such cases may have been associated with the aggressive behavior of these tumors. Our findings suggest that the characteristic morphology of invasive micropapillary carcinomas may be due to immunophenotypical and oncogenic changes.
authors.affiliation: Department of Pathology, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011, Japan. rin@med.kurume-u.ac.jp
authors.forename: Rin
authors.initials: R
authors.lastname: Yamaguchi
authors.forename: Maki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Keiko
authors.initials: K
authors.lastname: Kondo
authors.forename: Toshiro
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Miki
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ogata
authors.forename: Osamu
authors.initials: O
authors.lastname: Nakashima
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kage
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Yano
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D002291:Carcinoma, Papillary / Q000737:chemistry* / Q000473:pathology*; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011498:Protein Precursors / Q000032:analysis; D013194:Staining and Labeling
chemical_list: C081876:CKAP4 protein, human; D019394:Ki-67 Antigen; D008565:Membrane Proteins; D011498:Protein Precursors; C032253:involucrin