Expression of unusual immunohistochemical markers in mucinous breast carcinoma.
BACKGROUND
Mucinous breast carcinoma is characterized by the production of variable amounts of mucin. Some studies have addressed immunohistochemical characterization of mucinous breast carcinoma using a limited set of antibodies. However, the purpose of the present study was to investigate a larger panel of markers not widely used in daily practice and to determine their pathological implications.


METHODS
Forty patients diagnosed with mucinous breast carcinoma were enrolled. An immunohistochemical study was performed on whole sections of paraffin embedded tissue, using antibodies for the following markers: estrogen receptor alpha and beta, progesterone receptor, androgen receptor, HER2, EGFR, Ki-67, E-cadherin, β-catenin, p53, chromogranin, synaptophysin, GCDFP15, mammaglobin, and CDX2.


RESULTS
The pure mucinous type was more prevalent in older patients and more frequently expressed GCDFP15. Capella type B presented more frequently with a high Ki-67 index and neuroendocrine differentiation. Although there was a lower frequency of vascular invasion and lymph node metastases in the pure type, the difference was not statistically significant. No case expressed CDX2 (a marker for gastrointestinal tumors), while 85% of the cases expressed at least one of the two typical breast markers (GCDFP15 and mammaglobin), suggesting that these markers may be reliably used for differential diagnosis. Expression of estrogen receptor beta was related to the presence of mucin cell producing lymph node metastasis, with potential prognostic and predictive value.


CONCLUSIONS
our findings support the immunohistochemical homogeneity of mucinous breast carcinomas because only minor differences were found when subgrouping them into Capella types A and B or into types pure and mixed.
Laboratory of Investigative and Molecular Pathology, CIPED, Faculty of Medical Sciences, State University of Campinas, Rua Tessália Vieira de Camargo, 126, 13083-970, Campinas, São Paulo, Brazil; Laboratory of Investigative Pathology, Women's Hospital, CAISM, State University of Campinas, Rua Alexandre Fleming, 79, 13083-881, Campinas, SP, Brazil.
Rodrigo
R
de Andrade Natal
Department of Obstetrics and Gynecology, Faculty of Medical Sciences, State University of Campinas, Rua Tessália Vieira de Camargo, 126, 13083-970, Campinas, São Paulo, Brazil.
Sophie F
SF
Derchain
Laboratory of Investigative Pathology, Women's Hospital, CAISM, State University of Campinas, Rua Alexandre Fleming, 79, 13083-881, Campinas, SP, Brazil.
Marina
M
Pavanello
Laboratory of Investigative Pathology, Women's Hospital, CAISM, State University of Campinas, Rua Alexandre Fleming, 79, 13083-881, Campinas, SP, Brazil.
Geisilene R
GR
Paiva
Department of Obstetrics and Gynecology, Faculty of Medical Sciences, State University of Campinas, Rua Tessália Vieira de Camargo, 126, 13083-970, Campinas, São Paulo, Brazil.
Luis O
LO
Sarian
Laboratory of Investigative and Molecular Pathology, CIPED, Faculty of Medical Sciences, State University of Campinas, Rua Tessália Vieira de Camargo, 126, 13083-970, Campinas, São Paulo, Brazil. Electronic address: vassallomeister@gmail.com.
José
J
Vassallo
D002288:Adenocarcinoma, Mucinous / Q000235:genetics / Q000503:physiopathology*; D015415:Biomarkers / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000235:genetics / Q000503:physiopathology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry
D015415:Biomarkers; D014408:Biomarkers, Tumor
Capella type A and B; Estrogen receptor-beta; Neuroendocrine differentiation