Characteristic morphology of invasive micropapillary carcinoma of the breast: an immunohistochemical analysis.
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.
Yamaguchi
Rin
R
Department of Pathology, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011, Japan. rin@med.kurume-u.ac.jp
Tanaka
Maki
M
Kondo
Keiko
K
Yokoyama
Toshiro
T
Kaneko
Yuko
Y
Yamaguchi
Miki
M
Ogata
Yutaka
Y
Nakashima
Osamu
O
Kage
Masayoshi
M
Yano
Hirohisa
H
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
C081876:CKAP4 protein, human; D019394:Ki-67 Antigen; D008565:Membrane Proteins; D011498:Protein Precursors; C032253:involucrin