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Aims: Cytokeratin 5 (CK5) is a surrogate maker of progenitor cells and early glandular and myoepithelial cells (MECs) in the breast, and CK5 expression in breast MECs varies from ducts to lobules, and from normal to diseased tissue. However, the mechanisms underlying immunophenotypic alterations of CK5 expression in MECs remain unclear., Methods: CK5 expression in MECs of 20 normal breast samples, 58 ductal carcinoma in situ (DCIS; including 21 DCIS with extensive lobular involvement), 11 atypical ductal hyperplasia (ADH), 18 non-invasive lobular neoplasia consisting of 11 atypical lobular hyperplasia (ALH) and 7 lobular carcinoma in situ (LCIS), 20 cystic lobules and 10 usual ductal hyperplasia (UDH) involving lobules were observed to evaluate the effects of contact with benign hyperplastic or cancerous luminal cells and pressure of dilated glands on CK5 expression., Results: CK5 expression in normal ductal MECs was exclusively positive, whereas most normal lobular MECs were negative. In DCIS, cancerous ducts were primarily surrounded by CK5-positive MECs (91.0%), as were lobular acini involved by DCIS (89.2%), while the remaining normal acini maintained CK5-negative. CK5-positive MECs were found in 57.5% of acini in ALH and were more prevalent in LCIS (70.7%). CK5 expression was occasionally positive in both cystic lobules (16.7%) and lobules involved by UDH (14.3%), while an increase of CK5-positive MECs was found in ADH (38.2%)., Conclusions: These results suggest that CK5 expression in lobular MECs may be altered by contact with cancerous luminal cells rather than benign hyperplastic luminal cells or pressure from dilated glands., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Few studies have focused on converting ER-low-positive and HER2-low status following neoadjuvant therapy (NAT). We aimed to assess the evolution in ER and HER2 status after NAT in breast cancer patients., Patients and Methods: Our study included 481 patients with residual invasive breast cancer after NAT. ER and HER2 status were assessed in the primary tumor and residual disease, and associations between ER and HER2 conversion and clinicopathological factors were explored., Results: In primary tumors, 305 (63.4%) cases were ER-positive (including 36 cases of ER-low-positive), 176 (36.6%) were ER-negative. In residual disease, ER status changed in 76 (15.8%) cases, of which 69 cases switched from positive to negative. ER-low-positive tumors (31/36) were the most likely to change. In primary tumors, 140 (29.1%) tumors were HER2-positive, and 341 (70.9%) were HER2-negative (including 209 cases of HER2-low and 132 cases of HER2-zero). In residual disease, 25 (5.2%) cases had HER2 conversion between positive and negative. Considering HER2-low status, 113 (23.5%) cases had HER2 conversion, mostly driven by cases switching either to or from HER2-low. ER conversion had a positive correlation with pretreatment ER status (r = 0.25; P = .00). There was a positive correlation between HER2 conversion and HER2-targeted therapy (r = 0.18; P = .00)., Conclusion: Conversion of ER and HER2 status was observed in some breast cancer patients after NAT. Both ER-low-positive and HER2-low tumors showed high instability from the primary tumor to residual disease. ER and HER2 status should be retested in residual disease for further treatment decisions, especially in ER-low-positive and HER2-low breast cancer., Competing Interests: Disclosure We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “Effects of NAT on ER and HER2 status in breast cancer.”, (Copyright © 2023 Elsevier Inc. All rights reserved.)

Aims: This study was aimed to investigate the clinicopathological significance of immunohistochemical (IHC) Wilm's tumour 1 (WT1) expression in invasive breast carcinoma with >90% mucinous components., Methods: One hundred specimens of invasive breast carcinoma with >90% mucinous component were collected. All H&E-stained slides were reviewed, and the clinicopathological data, including sex, age, tumour size, nuclear grade, histological grade, growth pattern and lymph node (LN) status, were collected. IHC staining of WT1, oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and Ki-67 was performed. Fluorescence in situ hybridisation was used to verify the amplification of the HER2 gene. The relationship between WT1 expression and clinicopathological features was analysed statistically., Results: WT1 expression was detected in 67% (67/100) of invasive breast carcinoma with >90% mucinous components. WT1 expression was significantly associated with low-to-intermediate nuclear grade/histological grade, ER and PR positivity, HER2 negativity, Ki-67 proliferation index <30% and noLN metastasis (all p<0.001). Micropapillary architecture was observed in 80% of cases. WT1 expression was not significantly correlated with different percentage of micropapillary components (p=0.422). None of the histological grade 3 tumours, tumours with HER2 overexpression/amplification and triple-negative specimens showed WT1 expression., Conclusions: WT1 expression was significantly related with low-intermediate nuclear/histological grade, ER positivity, HER2 negativity, a lower Ki-67 proliferation index and no LN metastasis in invasive breast carcinoma with >90% mucinous component. The micropapillary growth pattern in this type of tumour did not show a specific relationship with WT1 expression., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Context.—: The updated American Society of Clinical Oncology/College of American Pathologists guideline for human epidermal growth factor receptor 2 (HER2) testing in breast cancer requires pathologists to re-evaluate HER2 status., Objective.—: To define HER2 status of breast cancer using immunohistochemistry and fluorescence in situ hybridization., Design.—: Diagnostic reports of invasive breast cancers made between 2014 and 2018 with HER2 immunohistochemistry and fluorescence in situ hybridization results were retrieved. HER2 status was re-defined using the updated recommendations., Results.—: Of 2514 tumors, 89.7% (2254 of 2514) suggested for fluorescence in situ hybridization assay were HER2 immunohistochemistry 2+. Approximately 8.9% (225 of 2514) and 1.4% (35 of 2514) of tumors were of immunohistochemistry 0/1+ and 3+, respectively. Based on the average HER2 copy number and HER2:CEP17 ratio, tumors were assigned into 5 groups, including 13.1% (330 of 2514) group 1 tumors, 2.1% (52 of 2514) group 2 tumors, 1.1% (27 of 2514) group 3 tumors, 7.0% (175 of 2514) group 4 tumors, and 76.8% (1930 of 2514) group 5 tumors. In combination with immunohistochemistry, all tumors in group 2 and group 4 changed HER2 status, from positive and equivocal into negative, respectively, while group 3 tumors remained positive. Comparative analyses of clinicopathologic features of tumors in different groups revealed that group 2 and 4 tumors displayed worse clinicopathologic features than those of group 5, while group 3 tumors shared similar clinicopathologic features to those of group 1., Conclusions.—: Following the updated guideline, HER2 status is clearly designated. Significant differences regarding clinical features were observed between tumors in different groups but they share the same HER2 status, suggesting further validation of the accuracy of this diagnostic approach is warranted., (© 2020 College of American Pathologists.)

Purpose: Ductal carcinoma in situ (DCIS) is a nonobligate precursor of invasive breast cancer. Here, we sought to investigate the level of intralesion genetic heterogeneity in DCIS and the patterns of clonal architecture changes in the progression from DCIS to invasive disease., Experimental Design: Synchronous DCIS ( n = 27) and invasive ductal carcinomas of no special type (IDC-NSTs; n = 26) from 25 patients, and pure DCIS ( n = 7) from 7 patients were microdissected separately and subjected to high-depth whole-exome ( n = 56) or massively parallel sequencing targeting ≥410 key cancer-related genes ( n = 4). Somatic genetic alterations, mutational signatures, clonal composition, and phylogenetic analyses were defined using validated computational methods., Results: DCIS revealed genetic alterations similar to those of synchronously diagnosed IDC-NSTs and of non-related IDC-NSTs from The Cancer Genome Atlas (TCGA), whereas pure DCIS lacked PIK3CA mutations. Clonal decomposition and phylogenetic analyses based on somatic mutations and copy number alterations revealed that the mechanisms of progression of DCIS to invasive carcinoma are diverse, and that clonal selection might have constituted the mechanism of progression from DCIS to invasive disease in 28% (7/25) of patients. DCIS displaying a pattern of clonal selection in the progression to invasive cancer harbored higher levels of intralesion genetic heterogeneity than DCIS where no clonal selection was observed., Conclusions: Intralesion genetic heterogeneity is a common feature in DCIS synchronously diagnosed with IDC-NST. DCIS is a nonobligate precursor of IDC-NST, whose mechanisms of progression to invasive breast cancer are diverse and vary from case to case., (©2020 American Association for Cancer Research.)

Invasive micropapillary carcinoma is characterized by the inside-out growth of tumor clusters and displays incomplete membrane immunostaining of HER2. According to the 2018 American Society of Clinical Oncology and the College of American Pathologists (ASCO/CAP) HER2-testing recommendation, moderate to intense but incomplete staining could be scored as immunohistochemical 2+. Furthermore, the criteria of immunohistochemical 3+ for this staining pattern are not mentioned. One hundred and forty-seven cases of invasive micropapillary carcinoma with moderate-to-intense HER2 immunostaining were enrolled. Invasive micropapillary carcinoma components of all cases were scored as immunohistochemical 2+ based on the 2018 ASCO/CAP recommendation. The invasive micropapillary carcinoma component varied from 10% to 100% (mean, 80%). Invasive micropapillary carcinoma components of all 147 tumors exhibited reversed polarity and incomplete basolateral HER2 membrane staining. One hundred and seventeen of the tumors (80%, 117/147) had moderate staining, and 38 (32%, 38/117) showed HER2 gene amplification by fluorescence in-situ hybridization. HER2 gene was amplified in all the remaining 30 tumors (20%, 30/147) that exhibited intense basolateral membrane staining. Besides, average HER2 signals per cell and ratio of HER2/CEP17 were significantly higher in the intense-staining tumors compared with the moderate-staining tumors (p < 0.0001). Follow-up data were available for 140 patients. None of the patients were died. The follow-up time ranged from 1 month to 99 months (median, 57 months). Thirteen (9%, 13/140) patients exhibited disease progression (recurrence or metastasis). HER2 gene amplification was correlated inversely with estrogen receptor (p = 0.000) and progesterone receptor (p = 0.000) expression, and positively with histological grade (p = 0.003) and disease progression (p = 0.000). Invasive micropapillary carcinoma with intense clear linear basolateral membrane immunostaining indicates HER2 positivity, even if the staining is incomplete. They should be classified as immunohistochemical 3+ rather than immunohistochemical 2+, which would avoid further fluorescence in-situ hybridization-testing procedure and greatly save the related time, labor, and financial costs. Ultimately, ensure all patients with HER2 gene amplification obtain effective targeted therapy in time.

Aims: Pure mucinous carcinoma (PMC) of the breast is a low-grade cancer. In this study, we aimed to elucidate the prognostic significance of micropapillary structures in breast PMC., Methods and Results: Seventy-five patients with breast PMC were recruited. All haematoxylin and eosin (H&)-stained slides were reviewed, and clinicopathological features including age, tumour size, growth pattern, nuclear grade, histological grade, lymph node (LN) status, immunohistochemistry (IHC) staining of hormone receptor, human epidermal growth factor receptor 2 (HER2) expression and Ki-67 proliferation index were analysed. Fluorescence in-situ hybridisation (FISH) was used to verify the amplification of the HER2 gene in IHC 2+ cases. Seventy-one cases of PMC were followed-up from 18 to 110 months (median = 68 months). All PMC patients were female, aged 31-83 years (median = 57 years). All PMCs were nuclear grades 1 or 2. Oestrogen receptor was positive in all cases (100%) and progesterone receptor was positive in 68 cases (90.7%). There was no 3+ staining or gene amplification of HER2. Four patients had axillary LN metastasis (5.7%). Micropapillae were observed in 60 cases (80%) with varied percentages, and divided into five groups: 0%, <20%, 20-49%, 50-89% and ≥90%, with 15 (20%), 15 (20%), 17 (22.7%), 17 (22.7%) and 11 (14.7%) cases in each. Follow-up results showed that neither recurrence nor distant metastasis occurred in all PMCs. Statistical analysis revealed that only larger tumour size was correlated significantly with LN metastasis (P < 0.05)., Conclusions: The presence of nuclear grades 1 or 2 micropapillae, irrespective of the percentage, had no significant relationship with LN metastasis and patients' survival of PMC., (© 2018 John Wiley & Sons Ltd.)

Pathogenic germline variants in ataxia-telangiectasia mutated (ATM), a gene that plays a role in DNA damage response and cell cycle checkpoints, confer an increased breast cancer (BC) risk. Here, we investigated the phenotypic characteristics and landscape of somatic genetic alterations in 24 BCs from ATM germline mutation carriers by whole-exome and targeted sequencing. ATM-associated BCs were consistently hormone receptor positive and largely displayed minimal immune infiltrate. Although 79.2% of these tumors exhibited loss of heterozygosity of the ATM wild-type allele, none displayed high activity of mutational signature 3 associated with defective homologous recombination DNA (HRD) repair. No TP53 mutations were found in the ATM-associated BCs. Analysis of an independent data set confirmed that germline ATM variants and TP53 somatic mutations are mutually exclusive. Our findings indicate that ATM-associated BCs often harbor bi-allelic inactivation of ATM, are phenotypically distinct from BRCA1/2-associated BCs, lack HRD-related mutational signatures, and that TP53 and ATM genetic alterations are likely epistatic.

Aims: To fully elucidate the clinicopathological features of breast carcinoma in sclerosing adenosis (SA-BC)., Methods: Clinical and histological characteristics of 206 SA-BCs from 180 patients were retrospectively evaluated. Immunohistochemical phenotype was examined. The clinicopathological relevance of the topographical pattern of SA-BCs was analysed., Results: Overall, up to 46 patients (25.6%) had contralateral cancer, either SA associated or not. Of 99 cases who underwent core needle biopsy (CNB), 36 were underestimated as adenosis or atypical ductal hyperplasia at CNB, 5 invasive cases were misinterpreted as in situ carcinomas, whereas 4 ductal carcinoma in situ (DCIS) cases were overdiagnosed as invasive carcinoma. Microscopically, 163 tumours were in situ, including 136 DCIS, 19 lobular carcinomas in situ (LCIS) and 8 mixed DCIS/LCIS; of these carcinomas in situ (CIS), 37 had microinvasion. The DCIS group exhibited low, intermediate and high grades in 53.7%, 34.6% and 11.8% of cases, respectively, mostly with solid (43.4%) or cribriform (41.9%) pattern. Forty out of 43 invasive cases were invasive ductal carcinoma (IDC), mostly DCIS predominant. Immunophenotypically, luminal A phenotype was identified in 55.1%, 63.2% and 45.0% of DCIS, LCIS and IDC cases, respectively. Topographical type A group (carcinoma being entirely confined to SA, n=176) was characterised by smaller size, less invasiveness, lower grade and more frequency of luminal A immunophenotype compared with type B group (≥ 50% but not all of the carcinomatous lesion being located in SA, n=30) (all P<0.05)., Conclusions: CIS, especially non-high-grade DCIS, represents the most common variant of SA-BC, and luminal A is the most predominant immunophenotype. CNB assessment might be challenging in some SA-BCs. The topographical pattern has great clinicopathological relevance. Careful evaluation of the contralateral breast and long-term follow-up for patients with SA-BC is necessary given its high prevalence of bilaterality., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: Ki67 labeling index (LI) is critical for treatment options and prognosis evaluation in breast cancer. Visual assessment (VA) is widely used to assess Ki67 LI, but has some limitations. In this study, we compared the consistency between VA and automated digital image analysis (DIA) of Ki67 LI in breast cancer, and to evaluate the application value of DIA in Ki67 LI assessment., Methods: Ki67 immunostained slides of 155 cases of primary invasive breast cancer were eyeballing assessed by five breast pathologists and automated digital image analyzed by one breast pathologist respectively. Two score methods, hot-spot score and average score, were used to choose score areas. The intra-class correlation coefficient (ICC) was used to analyze the consistency between VA and DIA, and Wilcoxon signed-rank test was used to compare the median of paired-difference between VA and DIA values., Results: (1) A perfect agreement was demonstrated between VA and DIA of Ki67 LI by ICC analysis (P<0.0001) in the whole cohort. A perfect agreement between VA and DIA of Ki67 LI was also showed in G2-G3, ER positive/HER2 negative cases. Average score and hot-spot score methods both demonstrated a perfect concordance between VA and DIA of Ki67 LI. (2) All cases were classified into three groups by VA values (≤10%, 11%-30% and >30% Ki67 LI). The concordance was relatively lower in intermediate Ki67 LI group (11%-30%) compared with high (>30%) Ki67 LI groups according to both methods. (3) All cases were classified into three groups by paired-difference (d) between VA values of hot-spot score and average score (d<5, 5≤d<10, d≥10) to evaluate the correlation between Ki67 staining distribution (heterogeneous or homogenous) and reproducibility of assessment. A perfect agreement was all demonstrated in three groups, and a slightly better Ki67 LI agreement between VA and DIA was indicated in homogenous staining slides than in heterogeneous staining ones. (4) VA values were relatively smaller than DIA values (average score: median of paired-difference -3.72; hot-spot score: median of paired-difference -9.12)., Conclusions: An excellent agreement between VA and DIA of Ki67 LI in breast cancer was demonstrated in the whole mixed cohort, suggesting that VA and DIA both could be used to assess Ki67 LI in clinical practice. Average score and hot-spot score methods both demonstrated a perfect concordance between VA and DIA of Ki67 LI. The almost perfect agreement between VA and DIA was observed in high Ki67 LI cases, displaying a homogenous staining pattern. The consistency between VA and DIA was relatively low in intermediate Ki67 LI group. The heterogeneity of tumors may slightly affect the concordance between VA and DIA of Ki67 LI. Assessment of VA provides lower Ki67 values than DIA, the biological importance of these values are not known at the moment.

The recent dramatic increase in breast cancer incidence across China with progressive urbanization and economic development has signaled the urgent need for molecular and clinical detailing of breast cancer in the Chinese population. Our analyses of a unique transethnic collection of breast cancer frozen specimens from Shanghai Fudan Cancer Center (Chinese Han) profiled simultaneously with an analogous Caucasian Italian series revealed consistent transcriptomic data lacking in batch effects. The prevalence of Luminal A subtype was significantly lower in Chinese series, impacting the overall prevalence of estrogen receptor (ER)-positive disease in a large cohort of Chinese/Caucasian patients. Unsupervised and supervised comparison of gene and microRNA (miRNA) profiles of Chinese and Caucasian samples revealed extensive similarity in the comprehensive taxonomy of transcriptional elements regulating breast cancer biology. Partition of gene expression data using gene lists relevant to breast cancer as "intrinsic" and "extracellular matrix" genes identified Chinese and Caucasian subgroups with equivalent global gene and miRNA profiles. These findings indicate that in the Chinese and Caucasian groups, breast neoplasia and the surrounding stromal characteristics undergo the same differentiation and molecular processes. Transcriptional similarity across transethnic cohorts may simplify translational medicine approaches and clinical management of breast cancer patients worldwide., (© 2015 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Background: Ki67 labeling index (LI) is used as a predictive marker and is associated with prognosis in breast cancer. However, standardised methodologies for measurement are lacking which has limited its application in clinical practice. In this study, we evaluated the interobserver concordance of visual assessment of Ki67 LI in breast cancer., Methods: Ki67-immunostained slides of 160 cases of primary invasive breast cancer were visual assessed by five breast pathologists with two different methods to choose the scoring fields: (1) hot-spot score, (2) average score. Proportions of positive invasive tumor cells at 10 % intervals were scored. The intra-class correlation coefficient (ICC) was used to assess the interobserver reproducibility., Results: (1) A perfect concordance of Ki67 LI was demonstrated according to both score methods (P<0.0001). Average score method (ICC, 0.904) demonstrated a better correlation than hot-spot score method (ICC, 0.894). (2) By respective means according to two score methods, all cases were classified into three groups (≤10%, 11%-30% and >30% Ki-67 LI). The concordance was relatively low in intermediate Ki67 LI group compared with low and high Ki67 LI groups. (3) All cases were classified into three groups by paired-difference (d) between means of hot-spot score and average score (d<5, 5≤d<10, d≥10). The consistency was observed to decrease with increasing paired-difference according to both methods., Conclusions: Visual assessment of Ki67 LI at 10 % intervals is a candidate for a standard method in breast cancer clinical practice. Average score and hot-spot score of visual assessment both demonstrated a perfect concordance, and an overall average assessment across the whole section including hot spots may be a better method. Interobserver concordance of intermediate Ki67 LI in which most cutoffs are located for making clinical decisions was relatively low.

Purpose: Invasive micropapillary breast carcinoma (IMPC) is a rare pathological finding. Few studies have compared IMPC with invasive ductal breast carcinoma (IDC) according to matched nodal status and age. To better illustrate the difference between IMPC and IDC prognoses, we conducted this cohort study., Methods: 51 mixed or pure IMPC patients and 102 pure IDC patients were matched for nodal status and age. Clinical and biological features as well as disease-free survival (DFS) were compared between groups., Results: More than one-half of IMPC consisted of mostly or exclusively IMPC component (meaning greater than 75%) and these tumors significantly correlated with a higher histologic grade (P = 0.016) and LVI positivity (P = 0.036) compared with mixed IMPC. IMPC displayed a significantly higher rate of estrogen receptor (ER) positivity and lymphovascular invasion (LVI) compared to matched IDC. Women diagnosed with IMPC had a slight, but not significant, reduced frequency for recurrence and metastasis compared to women with IDC (15.7% vs. 21.6%, P = 0.518). In the subgroup analysis, IMPC patients demonstrated significantly reduced survival (P = 0.018) compared to IDC patients in the T1N2-3 subpopulation, whereas IDC patients demonstrated significantly increased recurrence and metastasis (P = 0.024) compared to IMPC patients in the T2N2-3 subgroup. No difference was observed in patients with 3 or less positive lymph nodes (LNs)., Conclusion: Although no difference in DFS was observed between IMPC and LN-matched IDC patients, IMPC patients demonstrated a significantly poorer outcome compared to IDC patients with smaller tumors and 4 or more positive LNs. The opposite results were observed in larger tumors and patients with 4 or more positive LNs. Therefore, we might advise more proactive treatment for IMPC patients with a smaller tumor size and extensive LN involvement. Furthermore, correlative IMPC studies should focus on this subset of patients to elucidate the genetic and/or biologic differences that contribute to metastatic potential.

Objective: To investigate the clinicopathologic characteristics and differential diagnosis of the metastases to the breast from non-mammary malignancies., Methods: Twenty-eight cases were collected from 2004 to 2012;microscopic pathologic examinations and immunohistochemistry (EnVision method) were performed., Results: (1) All except one patients were female, ranging from 16 to 77 years old (average 45.8 years). Twenty-six (92.9%) patients initially presented with the primary site lesions; while the other two (7.1%) patients initially presented with breast lesions. The mean interval from primary diagnosis to detection of metastatic breast lesions was 32 months (0-228 months). Fifteen patients (53.6%) had other metastases detected simultaneously or preceded the breast lesions. (2) Macroscopically, all the tumors were relatively circumscribed, with a mean diameter of 4.0 cm (0.6-12.0 cm). The histological types of the corresponding primary tumors were as follows: eight (28.6%) cases from lung adenocarcinoma, five (17.8%) from high-grade ovarian serous carcinoma, three (10.7%) from gastric adenocarcinoma, two (7.1%) from rectal adenocarcinoma, one (3.6%) from pancreatic neuroendocrine carcinoma, one (3.6%) from prostatic carcinoma, four (14.3%) from melanoma, and four (14.3%) from mesenchymal malignant tumors (three rhabdomyosarcomas and one epithelioid malignant peripheral nerve sheath tumor, MPNST). (3) Histologically, the metastatic tumors showed the morphologic characteristics of the primary tumors. Lymph-vascular invasion was observed in 19 cases. Immunohistochemical features of metastatic tumors were consistent with the primary tumors. Molecular markers for breast such as GCDFP15 and mammaglobin were negative. Metastatic tumors from lung adenocarcinoma expressed TTF-1 (8/8). Ovarian serous carcinoma metastases were positive for PAX8 (5/5) and WT1 (4/5). Gastric adenocarcinoma metastases were positive for CDX2 (3/3) and villin (1/3). Rectal adenocarcinoma metastases were positive for CDX2 (2/2). Pancreatic neuroendocrine tumor metastasis was positive for Syn and CgA (both 1/1). Prostate carcinoma metastasis was positive for AR, PSA and P504S (all 1/1). Melanoma metastases were positive for HMB45 (2/3) and S-100 protein (3/3). Rhabdomyosarcoma metastases were positive for vimentin, desmin and myoD1 (all 3/3). MPNST metastasis was positive for S-100 protein (1/1). (4) Follow-up data was available in 17 patients, with median follow-up time 54 months. The median survival from diagnosis to breast metastasis was 24 months.Seven of 17 patients died., Conclusions: Metastases to the breast from non-mammary malignancies are rare and show pathologic features of primary tumors. It is usually presumed to be a primary breast carcinoma. Histopathologic features and clinical history in conjunction with the immunohistochemical results should be considered in differentiating a secondary mass from a primary breast carcinoma.

Objective: To study the clinicopathologic features, immunophenotype and differential diagnosis of cystic hypersecretory lesion (CHL) of the breast., Methods: Clinicopathologic and follow-up data of six cases of breast CHL in 2010-2013 were collected and reviewed.Immunohistochemical and mucinous staining was performed., Results: All six patients were female, age ranged from 37 to 71 years (average 49.3 years). Three cases were cystic hypersecretory hyperplasia (CHH), the other three cases were cystic hypersecretory carcinoma (CHC). Clinically the lesions presented as either breast mass or mammographic calcification.Grossly, the cystic hypersecretory lesions were poorly circumscribed, with multiple colloid containing cysts on the cut surface. Microscopically, the remarkable feature was numerous enlarged cysts which contained densely eosinophilic homogeneous secretion similar to the colloid seen in thyroid follicles, and calcification was seen in the cyst in one case. The secretion was D-PAS and mucicarmine positive. The lining epithelium of the cysts was uniformly flat, cuboid or columnar, and arranged in a monolayer. The cells may be arranged in turfs, solid or micropapillary patterns in CHH.In cases with dysplasia, the epithelium showed cytological and structural atypia, but the usual morphology of atypical dutal hyperplasia such as arcades, rigid bridges or cribriform pattern was less common. The three CHC included two invasive ductal carcinomas (IDC) and one ductal carcinoma in situ (DCIS).In CHL, there was immunoreactivity to S-100 protein, CK5/6 and CK14.Of the three CHCs, ER and PR were expressed in only one IDC.No HER2 expression was identified in the two invasive CHCs.One patient was lost to follow-up, and the rest were uneventful at 18 months., Conclusions: CHL of the breast is a rare pathological entity. Multiple colloid-filled cysts is a unique histological feature. The epithelium of CHL may show usual hyperplasia, dysplasia or carcinoma.

Objective: To investigate the clinicopathologic and immunohistochemical features as well as the differential diagnoses of the solid variant of mammary adenoid cystic carcinoma with basaloid features., Methods: Clinical and pathological data were collected in four cases of the solid variant of mammary adenoid cystic carcinoma with basaloid features, and microscopic pathological examination and immunohistochemistry EnVision method were performed. The relevant literature was also reviewed., Results: The four patients were female, with age ranged from 46 - 65 years old (average 56 years) and the maximum tumor diameter ranged from 1.5 to 2.5 cm. Microscopically, the tumors exhibited a predominantly solid architecture with a myxoid or hyalinized stroma. The tumor cells showed moderate to marked nuclear atypia, and a basaloid appearance with scanty cytoplasm and inconspicuous nucleoli, and ≥ 5 mitotic figures per 10 high power fields. Glandular space embedded within tumor islands could be noticed. These spaces were genuine glandular structures and the cells lining these true glandular lumens had more abundant and eosinophilic cytoplasm. Pseudoglandular spaces of cribriform pattern or variable shape were also occasionally seen, and these cysts contained homogenous eosinophilic material. Focal necrosis was found. All cases were negative for ER, PR and HER2. Immunohistochemical staining for CK5/6, CK7 and CK14 was positive in the genuine glandular structures. All cases were positive for CD10, but also positive with varying intensity from weak to strong for vimentin and CD117. Staining for Ki-67 in three patients showed 10% - 50% positive., Conclusions: The solid variant of mammary adenoid cystic carcinoma with basaloid features is a histologically distinctive and also a rare subset of the mammary adenoid cystic carcinoma. Awareness of its pathological features can help with the diagnosis as well as differential diagnosis. More cases are still needed for accurately assessing the prognosis of this particular tumor.

Matrix-producing carcinoma (MPC) of the breast is an extremely rare variant of metaplastic carcinoma. The aim of this study was to evaluate the clinicopathological features and immunohistochemical expression profile of this rare tumor in Chinese population. Thirteen cases of MPC were evaluated using morphology observation and immunohistochemistry. All tumors had invasive carcinoma with an abrupt transition to chondromyxoid matrix without an intervening spindle cell sarcomatoid component. The distribution of tumor cells was diffuse in eight cases and peripheral in five cases. Matrix distribution was diffuse or multifocal. Necrosis was present in 11 cases. An overt invasive ductal carcinoma was observed in 11 cases and the other two tumors were consistent with MPC arising in microglandular adenosis. Ten of 13 cases were triple negative (ER-, PR-, Her2/neu-). Eight of 10 triple negative cases were cytokeratin 5/6, cytokeratin 14 or epidermal growth factor receptor positive, consistent with the basal-like phenotype. S-100 protein was positive in all cases. At the time of initial diagnosis, one of 13 patients had lung metastasis and axillary lymph nodes metastasis. Follow-up time ranged from 6 to 30 months. All patients remained alive. One patient developed a soft tissue metastasis 24 months after surgery., (© 2011 The Authors. Pathology International © 2011 Japanese Society of Pathology and Blackwell Publishing Asia Pty Ltd.)