Gross cystic disease fluid protein‐15 and mammaglobin A expression determined by immunohistochemistry is of limited utility in triple‐negative breast cancer

Aims: In addition to oestrogen and progesterone receptors, gross cystic disease fluid protein‐15 (GCDFP‐15) and mammaglobin A (MAM) are the most common markers used to identify breast origin by immunohistochemistry. GCDFP‐15 expression has been reported in approximately 60% of breast carcinomas and MAM expression in approximately 80%. Data on their expression in triple‐negative breast cancer (TNBC) are very limited. The aim of this study was to examine the expression of these markers in TNBC to determine their utility in pathological diagnosis. Methods and results: We studied the immunohistochemical (IHC) expression of GCDFP‐15 and MAM in 63 primary and 118 metastatic TNBCs. GCDFP‐15 staining was present in 14% of primary and 21% of metastatic TNBCs. MAM staining was present in 25% of primary and 41% of metastatic TNBCs. The frequency of expression of GCDFP‐15 and/or MAM was 30% in primary and 43% in metastatic TNBCs, and many positive tumours had only focal staining. Conclusions: Staining for GCDFP‐15 and/or MAM in triple‐negative carcinomas helps to confirm breast origin, but most tumours in this subgroup of breast carcinomas lack expression of either marker.     

Insulin growth factor receptor‐1 expression and loss of PTEN protein predict early recurrence in triple‐negative breast cancer

Iqbal J, Thike A A, Cheok P Y, Tse G M‐K & Tan P H
(2012) Histopathology  61, 652–659 Insulin growth factor receptor‐1 expression and loss of PTEN protein predict early recurrence in triple‐negative breast cancer Aims: Insulin‐like growth factor receptor‐1 (IGFR‐1) and its signalling axis promote tumorigenesis, metastasis, and resistance to existing forms of cancer therapy, and have become a major focus for the development of anticancer drugs. As oncological management options for triple‐negative breast cancers (TNBCs) are limited, there is potential for the rapid development of novel selective anticancer agents specifically targeting components of the PTEN–phosphoinositide 3‐kinase–AKT pathway, including the phosphorylated form of AKT (pAKT) and the tumour suppressor molecule PTEN. The aim of this study was to conduct immunohistochemical analyses to examine the levels of PTEN, IGFR‐1 and pAKT expression in TNBCs, and determine whether these levels correlated with poor prognosis in this subset of aggressive breast cancers. Methods and results: Immunohistochemistry was performed on paraffin‐embedded tumour tissues from a consecutive cohort of 144 female patients diagnosed with TNBC. Associations of IGFR‐1, PTEN and pAKT expression with clinicopathological parameters, disease‐free survival (DFS) and overall survival (OS) were evaluated. There were significant increases in IGFR‐1 expression (99%) and pAKT expression (92%) with concomitant loss of PTEN expression in the majority of cases (63%). Increased IGFR‐1 expression and loss of PTEN expression were associated with reduced OS and DFS, respectively. pAKT expression showed a strong correlation with basal‐like expression. Combinatorial immunophenotypic analyses showed that loss of PTEN expression with concomitant IGFR‐1 expression correlated with poor DFS. Conclusions: A high percentage of PTEN loss with overexpression of IGFR‐1 and pAKT in TNBC indicates the potential of these molecules for predicting early recurrence and/or as targets in the formulation of effective alternative therapy regimens.     

Expression of calretinin by breast carcinoma and the potential for misdiagnosis of mesothelioma

Powell G, Roche H & Roche W R
(2011) Histopathology 59 , 950–956 Expression of calretinin by breast carcinoma and the potential for misdiagnosis of mesothelioma Aims: Calretinin and cytokeratin (CK)5/6 are frequently used to differentiate between metastatic breast cancer and primary malignant mesothelioma in pleural biopsies, but both tumours may express these markers. This study was aimed at evaluating the frequency of calretinin expression in primary breast carcinomas, and assessing the characteristics of the calretinin‐positive tumours. Methods and results: Fifty‐three primary breast adenocarcinomas were analysed for immunohistochemical expression of calretinin. CK5/6 and epidermal growth factor receptor (EGFR) immunostaining were performed on the calretinin‐positive subset. Tumours were classified as basal‐like if they met standard morphological and immunohistochemical criteria. Fifteen per cent (8/53) of the breast tumours were positive for calretinin. Eighty‐eight per cent (7/8) of the calretinin‐positive tumours were grade 3, as compared with 20% (9/45) of the calretinin‐negative tumours (P < 0.001). Only 13% (1/8) of the calretinin‐positive tumours were also oestrogen receptor (ER)‐positive, as compared with 87% (39/45) of the calretinin‐negative tumours (P < 0.001). Eleven per cent (6/53) of the tumours were classified as basal‐like. Of these, four were positive for calretinin and two were negative (P = 0.003). Conclusions: Fifteen per cent of breast carcinomas stain with calretinin. These tumours are more likely to be high‐grade, ER‐negative, and display a basal‐like phenotype. These tumours may be misdiagnosed as malignant mesothelioma when they metastasize to the pleura.     

Evaluation of androgen receptor and GATA binding protein 3 as immunohistochemical markers in the diagnosis of metastatic breast carcinoma to the lung

Differentiating metastatic breast carcinoma in the lungs from primary lung tumors and mesotheliomas is important for determining prognosis and treatment. We evaluated novel breast specific markers, androgen receptor (AR) and GATA binding protein 3 (GATA3) immunohistostaining, for this differential, and compare to other traditional markers. The specimens comprised 33 metastatic breast carcinomas to the lung, 566 primary lung tumors (170 adenocarcinomas, 157 squamous cell carcinomas, 31 pleomorphic carcinomas, 115 large cell neuroendocrine carcinomas, 43 small cell carcinomas, and 49 typical carcinoids) and 42 malignant mesotheliomas. They were analyzed by immunohistochemistry using antibodies to AR, GATA3, estrogen receptor (ER), progesterone receptor (PgR), mammaglobin, gross cystic disease fluid protein‐15 (GCDFP‐15). Of the metastatic breast carcinomas, immunohistostaining of AR, GATA3, ER, PgR, mammaglobin, GCDFP‐15 were positive in 27 cases (81.8%), 24 cases (72.7%), 26 cases (78.8%), 13 cases (39.4%), 12 cases (36.4%), 9 cases (27.3%), respectively. Of primary lung tumors and mesotheliomas, staining of AR, GATA3, ER, PgR, mammaglobin, GCDFP‐15 were positive in 18 cases (3%), 3 cases (0.5%), 4 cases (0.7%), 2 cases (0.3%), 0 case (0%), 2 cases (0.3%), respectively. Immunohistochemistry of AR and GATA3 are reliable for differentiating metastatic breast carcinoma from primary lung tumors and mesotheliomas.     

Cytokeratin profiles of male breast cancers

AIMS: The prognostic factors and expression of molecular markers in male breast carcinomas are similar to those in female breast cancers. The identification of distinct cytokeratin (CK) profiles (basal as opposed to luminal cells) helps to identify subsets of tumours with different clinical behaviour. The aim of this study was to investigate CK expression in male breast cancer. METHODS AND RESULTS: Thirty-two cases of male breast cancer were studied. The panel of CKs studied by immunohistochemistry included: 5/6, 14, 17, 18 and 19. Pathological findings and CK expression were analysed in all cases. Histological patterns included ductal carcinoma in situ, invasive ductal carcinoma and mixed patterns. Four cases were positive for CK5/6 and CK14, identifying a basal-like phenotype. CK17 was negative in all but two cases. All cases expressing either CK5/6 or CK14 were invasive carcinomas of high nuclear and histological grade and were also larger compared with the tumours not expressing CK5/6 and CK14. All tumours except three (also negative for CK5/6) expressed CK18 and CK19. The four basal-like tumours were negative for Her-2 expression. CONCLUSIONS: Male breast carcinomas have a basal-like phenotype that is similar in frequency to that of female breast carcinomas. The expression of CK5/6 and CK14 identifies a subset of pathologically aggressive male breast cancers.     

Relationship between molecular subtype of invasive breast carcinoma and expression of gross cystic disease fluid protein 15 and mammaglobin

We investigated the expression of gross cystic disease fluid protein 15 (GCDFP) and mammaglobin (MGB) by immunohistochemical analysis in 71 invasive breast carcinomas (IBCs) subtyped into luminal (A and B), HER2, basal-like carcinoma (BLC), and unclassified triple-negative carcinoma (UTNC) by established surrogate immunohistochemical profiles. GCDFP and MGB were less likely to be expressed in BLC than in HER2 cancers (P = .000021 and P = .013, respectively) or luminal cancers (P = .00002 and P = .00008, respectively). However, the difference in GCDFP or MGB expression between HER2 and luminal cancers was not significant (P = 1.0 and P = .671, respectively). Our results suggest that luminal cancers demonstrate similar degrees of apocrine differentiation as HER2 cancers. Most BLCs and UTNCs are negative for MGB and GCDFP. Correlation with clinical findings may be needed to exclude the possibility of a metastasis to the breast when BLCs or UTNCs are encountered in a limited sample such as a core biopsy sample.     

Mesothelial markers in high-grade breast carcinoma

Duhig E E, Kalpakos L, Yang I A & Clarke B E
(2011) Histopathology 59 , 957–964 Mesothelial markers in high‐grade breast carcinoma Aims: Advances in molecular profiling have subdivided breast carcinomas into distinct subtypes. Basal carcinomas are generally oestrogen receptor (ER)?progesterone receptor (PR)?/human epidermal growth factor receptor 2 (HER2)?, and cytokeratin (CK)5/6+. This profile overlaps with that of mesothelial cells. This study of high‐grade breast carcinomas was undertaken to determine the expression of mesothelial markers. Methods and results: Immunohistochemistry was performed on 23 basal‐like breast carcinomas and 30 high‐grade breast carcinomas with variable ER, PR and HER2 expression. The incidence of staining of CK5/6, CK14, calretinin, Wilms’ tumour 1 (WT1), thrombomodulin and epithelial membrane antigen was assessed statistically. CK14 staining was more specifically associated with triple‐negative tumours than CK5/6. Calretinin positivity was statistically associated with basal‐like carcinomas. WT1 and thrombomodulin expression was infrequent and limited to a small number of non‐basal carcinomas. Conclusions: There is an overlap between the immunophenotype of mesothelial cells and that of basal‐like carcinomas of breast. Positive calretinin and CK5/6 are not specific, and may be seen in both mesothelial cells and basal‐like breast carcinomas. Negative ER and PR of basal carcinomas may also bias the observer against a breast origin. However, other negative mesothelial markers, such as WT1 and thrombomodulin, may help point to the correct diagnosis.     

Secondary breast cancer: a 5‐year population‐based study with review of the literature

Secondary tumours in the breast are rare. Based on literature, an incidence of 0.4–2% is reported. In this population‐based study, secondary breast tumours from a 5‐year period (2001–2005), not including metastasis from contralateral breast carcinoma, were reviewed (Vestfold County, Norway). A total of 722 patients with breast malignancies were found in this population (89.3% from Vestfold County Hospital). Ten of these, approximately 1.4%, were metastatic tumours, representing four cutaneous melanomas, three pulmonary carcinomas and three malignant lymphomas. The tumours were often solitary, palpable and close to the skin. Radiologically, the lesions mostly resembled primary carcinomas by mammography and ultrasound, which differs from other studies. Comparison with a known primary tumour and use of immunohistochemical profiling is of crucial importance. Melanoma markers (Melan‐A, HMB‐45, S‐100 protein), lung cancer markers (Cytokeratins, TTF1, Chromogranin, Synapthophysin) and lymphoid markers (CD3, CD20) usually help to confirm a secondary breast tumour diagnosis. This approach is especially indicated in diffusely growing tumours with lack of glandular structure and high‐grade cytological features, and staining for ER and GCDFP15 may be helpful. Thus, the diagnosis of a breast metastasis may be suspected by careful mammography and ultrasound imaging, although some cases have atypical radiological features, and histological examination might be necessary to ensure a correct diagnosis and appropriate treatment.     

Diagnostic utility of mammaglobin and GCDFP‐15 in the identification of metastatic breast carcinoma in fluid specimens

Morphologic differentiation of breast carcinoma from nonmammary malignancies in fluid specimens can be a diagnostic challenge. Immunocytochemistry is often employed in the differential diagnosis. In this study, we evaluated the expression of mammoglobin (MGB1) in body‐cavity fluid specimens and compared its efficacy as a marker for metastatic breast carcinomas with that of gross cystic disease fluid protein‐15 (GCDFP‐15). Cell blocks from 40 fluid specimens were immunostained with monoclonal antibodies against MGB1 and GCDFP‐15. They included 15 breast carcinomas and 25 nonmammary carcinomas (10 lungs, 10 ovaries, 3 gastrointestinal tracts, 1 kidney, and 1 urinary bladder). Positivity was defined as the presence of cytoplasmic staining in 10% or more carcinoma cells. Thirteen (87%) and seven (47%) breast carcinomas showed positive staining with MGB1 and GCDFP‐15, respectively. Three (12%) nonmammary carcinomas (2 ovarian and 1 colonic) showed positive MGB1 staining; one (3%) nonmammary carcinoma demonstrated positive GCDFP‐15 staining. The differences of MGB1 and GCDFP‐15 staining between breast and nonmammary carcinomas were statistically significant (P < 0.05). Both MGB1 and GCDFP‐15 are specific markers for metastatic breast carcinomas in cell block fluid specimens (88 vs. 96%). However, MGB1 is more sensitive than GCDFP‐15 as a marker for metastatic breast carcinoma (87 vs. 46%). Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.     

P‐cadherin functional role is dependent on E‐cadherin cellular context: a proof of concept using the breast cancer model

P‐cadherin overexpression is associated with worse breast cancer survival, being a poor prognostic marker as well as a putative therapeutic target for the aggressive triple‐negative and basal‐like carcinomas (TNBCs). Previously, we have shown that P‐cadherin promotes breast cancer invasion of cells where membrane E‐cadherin was maintained; however, it suppresses invasion in models without endogenous cadherins, like melanomas. Here, we investigated if P‐cadherin expression would interfere with the normal adhesion complex and which were the cellular/molecular consequences, constituting, in this way, a new mechanism by which E‐cadherin invasive‐suppressor function was disrupted. Using breast TNBC models, we demonstrated, for the first time, that P‐cadherin co‐localizes with E‐cadherin, promoting cell invasion due to the disruption caused in the interaction between E‐cadherin and cytoplasmic catenins. P‐cadherin also induces cell migration and survival, modifying the expression profile of cells expressing wild‐type E‐cadherin and contributing to alter their cellular behaviour. Additionally, E‐ and P‐cadherin co‐expressing cells significantly enhanced in vivo tumour growth, compared with cells expressing only E‐ or only P‐cadherin. Finally, we still found that co‐expression of both molecules was significantly correlated with high‐grade breast carcinomas, biologically aggressive, and with poor patient survival, being a strong prognostic factor in this disease. Our results show a role for E‐ and P‐cadherin co‐expression in breast cancer progression and highlight the potential benefit of targeting P‐cadherin in the aggressive tumours expressing high levels of this protein. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

β‐Catenin and E‐cadherin expression in stage I adult‐type granulosa cell tumour of the ovary: correlation with tumour morphology and clinical outcome

Aims: To study E‐cadherin and β‐catenin expression in stage I adult‐type granulosa cell tumours (AGCTs) and correlate the findings with tumour morphology and clinical outcome. Methods and results: The study group comprised 62 FIGO stage I AGCTs, including 48 stage IA and 14 stage IC cases. Fifty patients (80.6%) had negative clinical follow‐up over periods from 3.0 to 19.2 years (median 6.4 years), and 12 patients (19.4%) developed metastases at intervals of 3.6–16.2 years (median 8.6 years). β‐Catenin and E‐cadherin were expressed in 62 (100%) and 53 (85%) primary tumours, respectively, and staining was more consistent and intense in areas showing sex cord‐like morphology. In contrast, diffuse tumour areas often showed weak or moderate staining (β‐catenin) or were negative (E‐cadherin), and there was reduced expression of both proteins in luteinized cells. Reduced β‐catenin expression in primary tumours correlated with increased risk of recurrence (P = 0.002) and a shorter time interval to recurrence, whereas there was no correlation between E‐cadherin staining and the risk of metastases. Conclusions: Localized variations in adhesion protein expression may partly explain the diverse morphological patterns exhibited by AGCT, and reduced β‐catenin staining in primary tumours may have value as an adverse prognostic factor.     

Centrally necrotizing carcinoma of the breast: clinicopathological analysis of 33 cases indicating its basal‐like phenotype and poor prognosis

Yu L, Yang W, Cai X, Shi D, Fan Y & Lu H
(2010) Histopathology 57 , 193–201 Centrally necrotizing carcinoma of the breast: clinicopathological analysis of 33 cases indicating its basal‐like phenotype and poor prognosis Aims: To investigate the clinicopathological features and immunophenotype of centrally necrotizing carcinoma (CNC) of the breast to ascertain its relationship to basal‐like phenotype and its prognosis. Methods and results: The clinical and pathological characteristics of 33 CNCs were reviewed. Immunohis‐tochemical study of oestrogen receptor, progesterone receptor, HER2, cytokeratin (CK) 8/18, high‐molecular‐weight CK (34βE12), CK5/6, CK14, CK17, smooth muscle antigen, p63, vimentin and epidermal growth factor receptor was performed. The striking feature of CNC was a central, necrotic or acellular zone surrounded by a ring‐like area of viable tumour cells. The central zone showed three morphological types: predominance of coagulative necrosis (21 cases), predominance of fibrosis and scar tissue (nine cases) and infarction (three cases). Tumour cells displayed invasive ductal carcinoma of high grade. The expression rate of basal‐like markers was higher than that of myoepithelial markers (87.9% versus 46.2%). Basal‐like subtype was shown by 63.6% of cases. The expression rate of CK5/6 (90.5%) was highest among basal‐like markers. Follow‐up data of 19 patients were available. Median progression‐free survival was 15.5 months. In 12 patients (63.2%), local recurrence and/or distant metastasis developed (median time to recurrence and/or metastasis, 14.0 months). Conclusions: CNC has distinctive morphological features, which mostly exhibit a basal‐like immunophenotype and poor prognosis. CNC is a typical representative of basal‐like breast cancer.     

Molecular classification of urothelial carcinoma: global mRNA classification versus tumour‐cell phenotype classification

Global mRNA expression analysis is efficient for phenotypic profiling of tumours, and has been used to define molecular subtypes for almost every major tumour type. A key limitation is that most tumours are communities of both tumour and non‐tumour cells. This problem is particularly pertinent for analysis of advanced invasive tumours, which are known to induce major changes and responses in both the tumour and the surrounding tissue. To identify bladder cancer tumour‐cell phenotypes and compare classification by tumour‐cell phenotype with classification by global gene expression analysis, we analysed 307 advanced bladder cancers (cystectomized) both by genome gene expression analysis and by immunohistochemistry with antibodies for 28 proteins. According to systematic analysis of gene and protein expression data, focusing on key molecular processes, we describe five tumour‐cell phenotypes of advanced urothelial carcinoma: urothelial‐like, genomically unstable, basal/SCC ‐like, mesenchymal‐like, and small‐cell/neuroendocrine‐like. We provide molecular pathological definitions for each subtype. Tumours expressing urothelial differentiation factors show inconsistent and abnormal protein expression of terminal differentiation markers, suggesting pseudo‐differentiation. Cancers with different tumour‐cell phenotypes may co‐cluster (converge), and cases with identical tumour‐cell phenotypes may cluster apart (diverge), in global mRNA analyses. This divergence/convergence suggests that broad global commonalities related to the invasive process may exist between muscle‐invasive tumours regardless of specific tumour‐cell phenotype. Hence, there is a systematic disagreement in subtype classification determined by global mRNA profiling and by immunohistochemical profiling at the tumour‐cell level. We suggest that a combination of molecular pathology (tumour‐cell phenotype) and global mRNA profiling (context) is required for adequate subtype classification of muscle‐invasive bladder cancer. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

mRNA markers of breast cancer nodal metastases: comparison between mammaglobin and carcinoembryonic antigen in 248 patients

Histological detection of axillary lymph node metastases is still the most valuable prognostic parameter for breast cancer, but about 30% of node-negative patients relapse within five years, suggesting that current methods are inadequate for identifying metastatic disease. More sensitive, PCR-based methods for the detection of metastatic cells are now available, enabling the amplification of cancer cell-specific mRNA messages by the RT-PCR assay. An ideal tumour marker, consistently expressed in tumour samples and not at all in normal lymph nodes, remains to be identified. The present study first investigated the expression of seven mRNA markers, CEA, CK19, c-Met, mammaglobin, MUC-1, beta1-->GalNAc-T and p97, selected on the basis of their previously reported specificity for breast cancer cells. Eighteen lymph nodes were examined from patients without tumours. Only mammaglobin mRNA and CEA mRNA were not expressed in normal nodes. All of the other markers showed a band of expression in 17%-55% of cases, indicating that they are not breast cancer-specific. CEA mRNA and mammaglobin mRNA expression could be detected in 15/20 (75%) and 19/20 (95%) primary breast carcinomas, respectively. The expression of mammaglobin mRNA and CEA mRNA was then compared in axillary lymph nodes from 248 consecutive breast cancer patients, 89 with histologically documented lymph node metastasis and 159 without histological evidence of metastatic disease. Ninety-seven per cent of the patients with histologically involved nodes showed expression of mammaglobin mRNA, whereas CEA mRNA was expressed in 79% of these cases. In the group of patients with histologically negative lymph nodes, 46 (29%) and 32 (20%) were found to be positive for mammaglobin and CEA expression, respectively, indicating the presence of metastases not detected by routine histological examination of one lymph node section. These results show that both mammaglobin RT-PCR and CEA RT-PCR are useful tools for the detection of breast cancer metastases in axillary lymph nodes. The detection sensitivity of the mammaglobin RT-PCR is far superior to that of the CEA RT-PCR, allowing the diagnosis of occult metastases in nearly one-third of cases.     

The many faces of acinic cell carcinomas of the salivary glands: a study of 40 cases relating histological and immunohistological subtypes to clinical parameters and prognosis

Schwarz S, Zenk J, Müller M, Ettl T, Wünsch P H, Hartmann A & Agaimy A
(2012) Histopathology  61, 395–408 The many faces of acinic cell carcinomas of the salivary glands: a study of 40 cases relating histological and immunohistological subtypes to clinical parameters and prognosis Aims: To study the morphological heterogeneity of acinic cell carcinoma (ACC) in correlation with clinicopathological parameters. Methods and results: Forty well‐characterized ACCs were classified as solid (n = 20), microcystic (n = 15), papillary‐cystic (n = 4) or follicular (n = 1), based on the dominant architectural growth pattern. Fourteen tumours exhibited eosinophilic/clear cell morphology and 18 tumours were rich in zymogen granules (so‐called blue dot tumours). High‐grade morphology occurred in five tumours. Based on cytokeratin (CK) 7 staining and in analogy to CK7 expression in normal salivary gland epithelia, three distinct histogenetic subtypes were recognized: acinar (CK7‐negative; n = 13), ductular (diffuse CK7‐positive; n = 11) and mixed ductulo‐acinar (10–66% CK7‐positive cells; n = 16). Most papillary‐cystic tumours displayed ductular differentiation (P = 0.015), whereas blue dot tumours never did (P < 0.001). Analysis of relapse‐free survival (RFS) revealed that Stage I tumours had the best prognosis without any relapse in 18 years follow‐up (P = 0.06). High‐grade tumours were associated with shorter RFS (P = 0.028). Concerning the histogenetic types, monophasic (pure acinar or ductular) tumours were associated with a significantly better RFS than mixed ductulo‐acinar tumours (P = 0.008). Conclusion: The results underscore the great histological diversity of ACC, and the value of histogenetic subtyping as an additional prognostic factor regarding RFS.     

Epidermal growth factor receptor gene amplification and protein overexpression in basal-like carcinoma of the breast

Shao M‐M, Zhang F, Meng G, Wang X‐X, Xu H, Yu X‐W, Chen L‐Y & Tse G M
(2011) Histopathology 59 , 264–273 Epidermal growth factor receptor gene amplification and protein overexpression in basal‐like carcinoma of the breast Aims: Epidermal growth factor receptor (EGFR) is frequently expressed in basal‐like breast cancer (BLBC). The aim of this study was to evaluate their correlation as detected by immunohistochemistry (IHC) or fluorescence in‐situ hybridization (FISH). Methods and results: IHC for oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor (HER) 2, cytokeratin (CK) 5/6 and EGFR, and FISH for EGFR amplification, were performed in 59 cases of BLBC. EGFR IHC results were scored semiquantitatively, and compared with its gene amplification status. ER, PR and HER2 were negative in all cases, whereas 35 and 55 cases were positive for CK5/6 and EGFR. For EGFR IHC, 20, 11, 11 and 17 cases showed a negative, a low, an intermediate or a high staining level, respectively, and seven cases showed gene amplification by FISH, with two, 19, 11 and 20 cases showing balanced monosony, disomy, trisomy, and polysomy respectively. Immunohistochemical expression in gene‐amplified tumours was significantly higher than in those without amplification, including balanced polysomy tumours. EGFR immunohistochemical expression also correlated with the EGFR/chromosome 7 ratio. High sensitivity (86%) and negative predictive value (98%) were achieved with high‐level immunohistochemical expression as a cut‐off to predict gene amplification. Conclusions: High‐level EGFR immunohistochemical expression correlated with and predicted EGFR amplification, and may be used as a screening method to exclude gene amplification.     

Salivary duct carcinomas can be classified into luminal androgen receptor‐positive,HER2 and basal‐like phenotypes*

Di Palma S, Simpson R H W, Marchiò C, Skálová A, Ungari M, Sandison A, Whitaker S, Parry S & Reis‐Filho J S
(2012) Histopathology  61, 629–643 Salivary duct carcinomas can be classified into luminal androgen receptor‐positive, HER2 and basal‐like phenotypes Aims: The aim of this study was to devise a molecular classification for salivary duct carcinomas (SDCs) based on the similarities between SDCs and breast carcinomas and on characteristics of the microarray‐based gene expression profiling‐defined molecular subtypes of breast cancer. Methods and results: Forty‐two pure salivary duct carcinomas, 35 of which contained an in‐situ component as defined by histological review and/or immunohistochemical analysis, were stained with antibodies for oestrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR) and cytokeratin (CK) 5/6. Based on these markers, tumours were classified into HER2, luminal androgen receptor‐positive, basal‐like, luminal and indeterminate phenotype. Analysis revealed that 16.7%, 69%, 4.8%, 9.5% and 0% were of HER2, luminal androgen receptor‐positive, basal‐like, indeterminate and luminal phenotype, respectively. The in‐situ and invasive components displayed the same molecular subtype in all but one case. Conclusions: Salivary duct carcinomas can be classified into molecular subgroups approximately equivalent to those in the breast. We also report on the existence of a subgroup of bona fide pure salivary duct carcinomas that have a ‘basal‐like’ phenotype. Understanding the phenotypic complexity of SDCs may help to expedite the identification of novel therapeutic targets for these aggressive tumours.     

Patterns of distribution of cytokeratins 20 and 7 in special types of invasive breast carcinoma: a study of 123 cases

Metastatic adenocarcinomas of unknown primary site are a common clinical problem. Invasive ductal carcinomas of the breast and some special types of invasive breast carcinoma are common sources of metastases. Immunohistochemical algorithms, such as a combination of cytokeratins 20 and 7, can be helpful in this situation. Detailed phenotyping of the different types and subtypes of primary invasive carcinomas and their metastases is an essential prerequisite for a successful search for an unknown primary tumor. A series of 123 primary invasive breast adenocarcinomas of special type and of 27 lymph node metastases was analyzed. Sections of selected blocks were stained with two monoclonal cytokeratin antibodies (CK20 and CK7) and evaluated as negative (no staining), focally positive or diffusely positive. Of the 123 carcinomas, 113 (92%) proved to be CK20 negative. Three of 82 (4%) invasive lobular carcinomas, three of 11 (27%) mucinous carcinomas, one of 10 (10%) tubular carcinomas, and one invasive papillary carcinoma stained diffusely with CK20. Additionally, a tubulolobular carcinoma and a medullary carcinoma showed focal CK20 positivity. One hundred twenty (98%) of the 123 tumors were CK7 positive, five of them only focally. One of the four solid invasive lobular carcinomas, one medually carcinoma, and one invasive papillary carcinoma were completely negative for CK7. Only two cases, one mucinous and one invasive papillary carcinoma, exhibited the CK20(+)/CK7(-) ("colorectal") pattern. One of the lymph node metastases was CK20(+); another was CK7(-). Like their ductal counterparts, invasive breast carcinomas of special type are usually CK20(-)/CK7(+); they generally retain this phenotype in their metastases. However, there are CK20-positive special-type breast carcinomas that can be confused with gastrointestinal or pancreaticobiliary carcinoma in metastases, especially if they are mucinous or invasive lobular.     

The repertoire of somatic genetic alterations of acinic cell carcinomas of the breast: an exploratory,hypothesis‐generating study

Acinic cell carcinoma (ACC) of the breast is a rare form of triple‐negative (that is, oestrogen receptor‐negative, progesterone receptor‐negative, HER2‐negative) salivary gland‐type tumour displaying serous acinar differentiation. Despite its triple‐negative phenotype, breast ACCs are reported to have an indolent clinical behaviour. Here, we sought to define whether ACCs have a mutational repertoire distinct from that of other triple‐negative breast cancers (TNBCs). DNA was extracted from microdissected formalin‐fixed, paraffin‐embedded sections of tumour and normal tissue from two pure and six mixed breast ACCs. Each tumour component of the mixed cases was microdissected separately. Tumour and normal samples were subjected to targeted capture massively parallel sequencing targeting all exons of 254 genes, including genes most frequently mutated in breast cancer and related to DNA repair. Selected somatic mutations were validated by targeted amplicon resequencing and Sanger sequencing. Akin to other forms of TNBC, the most frequently mutated gene found in breast ACCs was TP53 (one pure and six mixed cases). Additional somatic mutations affecting breast cancer‐related genes found in ACCs included PIK3CA, MTOR, CTNNB1, BRCA1, ERBB4, ERBB3, INPP4B, and FGFR2. Copy number alteration analysis revealed complex patterns of gains and losses similar to those of common forms of TNBCs. Of the mixed cases analysed, identical somatic mutations were found in the acinic and the high‐grade non‐acinic components in two out of four cases analysed, providing evidence of their clonal relatedness. In conclusion, breast ACCs display the hallmark somatic genetic alterations found in high‐grade forms of TNBC, including complex patterns of gene copy number alterations and recurrent TP53 mutations. Furthermore, we provide circumstantial genetic evidence to suggest that ACCs may constitute the substrate for the development of more aggressive forms of triple‐negative disease. Copyright © 2015 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.