Single-cell and spatial profiling identify three response trajectories to pembrolizumab and radiation therapy in triple negative breast cancer.

Strategies are needed to better identify patients that will benefit from immunotherapy alone or who may require additional therapies like chemotherapy or radiotherapy to overcome resistance. Here we employ single-cell transcriptomics and spatial proteomics to profile triple negative breast cancer biopsies taken at baseline, after one cycle of pembrolizumab, and after a second cycle of pembrolizumab given with radiotherapy. Non-responders lack immune infiltrate before and after therapy and exhibit minimal therapy-induced immune changes. Responding tumors form two groups that are distinguishable by a classifier prior to therapy, with one showing high major histocompatibility complex expression, evidence of tertiary lymphoid structures, and displaying anti-tumor immunity before treatment. The other responder group resembles non-responders at baseline and mounts a maximal immune response, characterized by cytotoxic T cell and antigen presenting myeloid cell interactions, only after combination therapy, which is mirrored in a murine model of triple negative breast cancer.

Comparative expression of trophoblast cell-surface antigen 2 (TROP2) in the different molecular subtypes of invasive breast carcinoma: An immunohistochemical study of 94 therapy-naive primary breast tumors.

BACKGROUND: Sacituzumab govitecan, targeting trophoblast cell-surface antigen 2 (TROP2), is approved for the treatment of triple-negative and hormone receptor-positive/HER2-negative breast cancers. However, detailed studies comparing TROP2 protein expression in the different molecular subtypes of breast cancer are limited, and definitive evidence supporting the use of TROP2 as a biomarker for predicting response to this agent in patients with breast cancer is currently lacking. OBJECTIVE: To compare the expression of TROP2 in the different molecular subtypes of breast cancer. METHODS: Immunohistochemical staining for TROP2 was performed on 94 therapy-naive primary invasive breast carcinomas, including 25 luminal A-like, 25 luminal B-like, 19 HER2-like, and 25 triple-negative tumors. RESULTS: Intermediate to high levels of TROP2 expression were observed in the majority of carcinomas of each molecular subtype, with a wide range of expression in each subtype. Occasional tumors with low or absent TROP2 expression were encountered, including two metaplastic carcinomas which were completely negative for TROP2. CONCLUSIONS: Our observations support the continued investigation of the efficacy of sacituzumab govitecan in all molecular subtypes of breast carcinoma. Furthermore, the observed wide range of expression of TROP2 suggests that TROP2 may have potential utility as a biomarker for predicting responsiveness to sacituzumab govitecan. If this proves to be the case, then immunohistochemical staining for TROP2 would be critical for identifying those patients whose tumors are completely negative for TROP2, since these patients may be least likely or unlikely to respond to this agent, and alternative therapies may be more appropriate in such instances.

The Genetic Landscape of Fibroepithelial Lesions of the Breast.

Fibroepithelial lesions of the breast encompass a broad spectrum of lesions from fibroadenomas and their variants to phyllodes tumors, including their clinical range of benign, borderline, and malignant. Classification of this spectrum of neoplasms has historically and currently been based purely on morphology, although the nomenclature has shifted over the years largely due to the significant histologic overlap that exists primarily within the cellular fibroadenomas to borderline malignant phyllodes tumor categories. A review of the current diagnostic challenge, proposed ancillary studied and their value in prognostic significance, is provided. This article highlights the most recent molecular and genetic findings as well as the limitations of the studies, in the context of practical and available applications for the diagnostician and managerial implications for the clinician.

Gene Expression Profiling of Fibroepithelial Lesions of the Breast.

Fibroepithelial lesions of the breast (FELs) are a heterogeneous group of neoplasms exhibiting a histologic spectrum ranging from fibroadenomas (FAs) to malignant phyllodes tumors (PTs). Despite published histologic criteria for their classification, it is common for such lesions to exhibit overlapping features, leading to subjective interpretation and interobserver disagreements in histologic diagnosis. Therefore, there is a need for a more objective diagnostic modality to aid in the accurate classification of these lesions and to guide appropriate clinical management. In this study, the expression of 750 tumor-related genes was measured in a cohort of 34 FELs (5 FAs, 9 cellular FAs, 9 benign PTs, 7 borderline PTs, and 4 malignant PTs). Differentially expressed gene analysis, gene set analysis, pathway analysis, and cell type analysis were performed. Genes involved in matrix remodeling and metastasis (e.g., MMP9, SPP1, COL11A1), angiogenesis (VEGFA, ITGAV, NFIL3, FDFR1, CCND2), hypoxia (ENO1, HK1, CYBB, HK2), metabolic stress (e.g., UBE2C, CDKN2A, FBP1), cell proliferation (e.g., CENPF, CCNB1), and the PI3K-Akt pathway (e.g., ITGB3, NRAS) were highly expressed in malignant PTs and less expressed in borderline PTs, benign PTs, cellular FAs, and FAs. The overall gene expression profiles of benign PTs, cellular FAs, and FAs were very similar. Although a slight difference was observed between borderline and benign PTs, a higher degree of difference was observed between borderline and malignant PTs. Additionally, the macrophage cell abundance scores and CCL5 were significantly higher in malignant PTs compared with all other groups. Our results suggest that the gene-expression-profiling-based approach could lead to further stratification of FELs and may provide clinically useful biological and pathophysiological information to improve the existing histologic diagnostic algorithm.

Incidence and prognostic impact of HER2-positivity loss after dual HER2-directed neoadjuvant therapy for HER2+ breast cancer.

BACKGROUND: Loss of HER2 "positivity" can occur in patients with residual disease after neoadjuvant treatment, but the incidence of HER2-positivity loss after neoadjuvant dual HER2-targeted treatment plus chemotherapy, the current standard-of-care for most early stage HER2-positive breast cancers, is not well described. Previous studies that report the HER2 discordance rate after neoadjuvant treatment also do not include the novel HER2-low category. In this retrospective study, we determine the incidence and prognostic impact of HER2-positivity loss, including the evolution to HER2-low disease, after neoadjuvant dual HER2-targeted therapy with chemotherapy. METHODS: Clinicopathologic data for patients with stage I-III HER2+ breast cancer diagnosed between 2015 and 2019 were reviewed in this single institution retrospective study. Patients who received dual HER2-targeted treatment with chemotherapy were included, and HER2 status before and after neoadjuvant therapy was interrogated. RESULTS: A total of 163 female patients were included in the analysis with a median age of 50 years. A pathologic complete response (pCR as defined by ypT0/is) was achieved in 102 (62.5%) of 163 evaluable patients. Among the 61 patients with residual disease after neoadjuvant therapy, 36 (59.0%) had HER2-positive and 25 (41.0%) had HER2-negative residual disease. Of the 25 patients with HER2-negative residual disease, 22 (88%) of patients were classified as HER2-low. After a median follow-up of 3.3 years, patients who retained HER2-positivity after neoadjuvant treatment had a 3-year IDFS rate of 91% (95% CI, 91%-100%), while patients who lost HER2-positivity had a 3-year IDFS rate of 82% (95% CI, 67%-100%). CONCLUSION: Almost half of patients with residual disease following neoadjuvant dual HER2-targeted therapy plus chemotherapy lost HER2-positivity. The loss of HER2-positivity may not confer negative prognostic impact, although the results were limited by short follow-up time. Further research on the HER2 status after neoadjuvant treatment may help guide treatment decisions in the adjuvant setting.

Upstaging of Fibroepithelial Lesions: A Single-Institution Experience.

INTRODUCTION: Fibroepithelial lesions of the breast (FEL) are heterogeneous lesions ranging from fibroadenomas (FA) to phyllodes tumors (PT). FEL with cellular stroma are diagnostic challenges on core needle biopsy (CNB) as it is difficult to distinguish cellular FA from PT. The purpose of this study was to determine the features of FEL on CNB that may be predictive of PT, the upstage rate to PT after excision, and the outcomes of those who did not undergo excision. METHODS: Overall, 305 patients with FEL on CNB between 2009 and 2019 were identified from a prospectively maintained institutional database. Presentation, imaging, and pathology were evaluated. RESULTS: Mean age at diagnosis was 43.8 years. Pathology on CNB included 97 cases of FEL favoring FA, 19 cases of FEL favoring PT, 3 cases of FEL versus pseudoangiomatous stromal hyperplasia, and 186 cases of FEL not otherwise specified. Following CNB, 96 (31.5%) patients were observed, 158 (51.8%) patients had an excisional biopsy, 48 (15.7%) patients underwent segmental mastectomy, and 3 (1.0%) patients underwent a mastectomy. The upgrade rate from FEL on CNB to PT upon excision was 25.8%. PT on final pathology was more commonly seen when the CNB identified stromal overgrowth, necrosis, and diagnosis of FEL favoring PT. On multivariable analysis, a final diagnosis of PT was associated with age >50 years, larger tumor size >2 cm, stromal overgrowth, and ≥1 mitoses/10 high power fields (HPF) on CNB. Patients who were observed had smaller tumors compared with those who underwent excision. CONCLUSION: In this 10-year single-institution experience of FEL, the upstage rate to PT was 25.8%. Excision of FEL is recommended. Furthermore, the observation of lesions appeared to be safe in select cases, specifically in patients with smaller tumor size.

Clinicopathologic Characteristics and Patient Outcomes of Phyllodes Tumors: A Single Institution Experience.

Phyllodes tumors (PT) are rare fibroepithelial neoplasms that are classified as benign, borderline, or malignant. Patients with PT diagnosed between 2009 and 2019 were identified from a prospectively maintained single institutional database. 76 patients with PT were included; 47 (61.8%) were benign, 9 (11.8%) were borderline, and 20 (26.3%) were malignant. The mean age at diagnosis was 52. Surgical treatment of benign PT included excisional biopsy in 31 (66.0%) patients, segmental mastectomy in 15 (31.9%), and mastectomy in 1 (2.1%). Among patients with borderline PT, operative management was excisional biopsy in 4 (44.4%) and segmental mastectomy in 5 (55.6%). Of those with malignant PT, 7 (35.0%) were treated with excisional biopsy alone, 9 (45.0%) had lumpectomy (segmental mastectomy), and 4 (20.0%) underwent mastectomy. Malignant PT had a higher rate of necrosis compared to borderline or benign PT (25.0% vs 0% vs 4.3%, P = .016). Four patients had recurrent PT. Final positive margins were associated with recurrence (P = .044). The median overall follow-up time was 86.3 months (range 1.5-1414.1 months), and no deaths occurred among patients with malignant PT. Overall, recurrence rates of PT are low but may be increased by presence of positive margins.

Comparison of multiple oncotype DX® from the same patient.

For women with breast cancer in whom multiple Oncotype DX® Recurrence Scores (RS) are obtained, RS concordance utilizing current NCCN recommendations has not been evaluated. Patients with two or more RS were identified. RS were stratified by NCCN guidelines and compared for concordance. Twenty-four patients were evaluated. RS concordance varied by tumor type: 100% in the same tumor, 91.7% in multiple ipsilateral tumors, 71.4% in contralateral tumors, and 66.7% in in-breast recurrent tumors. RS concordance for multiple assays in the same patient is not high enough to omit Oncotype DX® testing for each tumor.

Gene expression comparison between primary estrogen receptor-positive and triple-negative breast cancer with paired axillary lymph node metastasis.

The aim of this study is to characterize and compare changes in gene expression patterns of paired axillary lymph node (ALN) metastases from estrogen receptor (ER)-positive and triple-negative (TNBC) primary breast cancer (PBC). Patients with stage 2-3 PBC with macrometastasis to an ALN were selected. Gene expression of 2567 cancer-associated genes was analyzed with the HTG EdgeSeq system coupled with the Illumina Next Generation Sequencing (NGS) platform. Changes in gene expression between ER/PR-positive, HER2-negative PBC, and their paired ALN metastases were compared with TNBC and their paired ALN metastases. Fourteen pairs of ER-positive and paired ALN metastasis were analyzed. Compared with the PBC, ALN metastasis had 673 significant differentially expressed genes, including 348 upregulated genes and 325 downregulated genes. Seventeen pairs of TNBC and paired ALN metastasis were analyzed. ALN metastasis had 257 significant differentially expressed genes, including 123 upregulated genes and 134 downregulated genes. When gene expression of the ALN for ER-positive PBC was compared to that of TNBC, 97 genes were upregulated in both, and 115 genes were similarly downregulated. Common upregulated genes were associated with cell death, necrosis, and homeostasis. Common downregulated genes were those of migration, degradation of extracellular matrix, and invasion. Although ER-positive PBC and TNBC have a distinct gene expression profiles and distinct changes from PBC to ALN metastases, a significant number of genes are similarly up- or downregulated. Understanding the role of these common genomic changes may provide clues to understanding the metastatic process itself.

Flat epithelial atypia on core needle biopsy does not always mandate excisional biopsy.

Flat Epithelia Atypia (FEA) is a proliferative lesion of the breast where cells demonstrate columnar change and cytologic atypia. This lesion has been identified as distinct from the classic atypical hyperplasias (AH). While many patients undergo excisional biopsy, management of FEA identified on core needle biopsy (CNB) is controversial, and the rate of associated ductal carcinoma in situ (DCIS) or invasive cancer is not well defined. The aim of this study was to determine the upstage rate of FEA diagnosed by CNB. We identified patients from a prospectively maintained data base who had FEA diagnosed by CNB from 01/2010 to 07/2015. Patient variables collected included age at presentation, imaging findings, pathologic findings following surgical excision, and subsequent development of breast cancer. Of 132 patients, 62 (n = 62/132, 47.0%) patients had FEA associated with DCIS and invasive ductal carcinoma (IDC) on CNB and were excluded from analysis. Of the remaining 70 patients, median age was 52 (range 31-84) years. Thirty-two (45.7%) patients had FEA plus AH, 4 (5.7%) patients had FEA plus lobular carcinoma in situ (LCIS), and 34 (48.6%) patients had FEA alone or with another non-pathologic finding (pure FEA). Two (6.3%) patients with FEA plus AH had DCIS or IDC on subsequent excisional biopsy. Of the 34 patients with pure FEA who underwent excisional biopsy, only one (2.9%) was found to have IDC. Twenty-two (64.7%) patients with pure FEA who underwent excisional biopsy presented with calcifications on mammography. None of these patients had cancer on excisional biopsy, and 10 (45.5%) patients had AH (3 ADH, 3 ALH, and 4 both ALH and ADH). Twelve (n = 12/34, 35.3%) patients with pure FEA underwent CNB for a mass or asymmetry noted on imaging. Of these 12 patients, 9 (75.0%) had benign findings on excisional biopsy, two (16.7%) patients had AH, and one (8.3%) patient had IDC. Median follow-up was 4.6 years (IQR 3.1-6.5 years). Three (4.3%) patients subsequently developed IDC, two of which were in the contralateral breast. FEA is often found in combination with ADH and ALH as well as carcinoma on CNB. In our study, pure FEA was upstaged to cancer in only 2.9% of patients. Mammographic findings unlikely predict upstaging to malignancy. These findings suggest that excisional biopsy may not be warranted in patients with pure FEA and could be managed with close imaging surveillance.

Gene expression comparison between primary triple-negative breast cancer and paired axillary and sentinel lymph node metastasis.

Few studies examine the genomics of axillary lymph node (ALN) metastasis in triple-negative breast cancer (TNBC). The aim was to characterize and compare gene expression patterns of primary breast cancers and paired ALN metastases. Patients with stage 2-3 ER/PR negative, HER2 negative TNBC with ALN macrometastasis without neo-adjuvant therapy were selected. Tumor-specific area was isolated from breast and ALN tissue sections. Gene expression of 2567 cancer-associated genes was analyzed with the HTG EdgeSeq system coupled with Illumina next-generation sequencing (NGS). Seventeen pairs of TNBC and autologous ALN metastasis were analyzed. Compared with the primary, ALN metastasis had 257 statistically significant differentially expressed genes, including 123 upregulated genes and 134 downregulated genes. Notably, there was an upregulation of anti-apoptosis and survival signaling genes (BIRC3, TCL1A, FLT3, and VCAM1) in the ALN metastasis. There was also an upregulation of chemotaxis genes (CCL19, CCL21, CXCL13, and TNFSF11). The most striking feature is the downregulation of genes known to regulate cell microenvironment interaction (MMP2, MMP 3, MMP 7, MMP 11, MMP14, COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, COL6A6, COL11A1, and COL17A1). In TNBC, ALN metastases have a distinct gene expression profile. Genes associated with anti-apoptosis, survival responses, and chemotaxis are upregulated, and genes associated with regulation of extracellular matrix are downregulated when compared to autologous primary cancer. TNBC cells metastatic to lymph nodes undergo a change in order to metastasize and survive in the new microenvironment, which may lead to insights into the metastatic process.

High-grade ovarian serous carcinomas: Significant correlation of histologic patterns with IMP3 and E-Cadherin predicting disease recurrence and survival.

Most high-grade serous carcinomas (HGSC) of the ovary are advanced stage tumors with early recurrences. However, some tumors do not recur and have a better survival. We identified such cases of HGSC and compared those with the cases that recurred and assessed the relationship between patterns of invasion (intracystic, IC; micropapillary, MP; nonpapillary, NP) with IMP3 and E-Cadherin expression, and evaluated their predictive role in recurrence and survival. The study comprised of seventeen tumors recurred within 18 months of follow-up and 14 cases that did not recur with a minimum follow-up of 49 months. 73% tumors with predominantly MP pattern recurred, while only 27% of non-recurrent tumors showed this pattern. In contrast, predominant NP and IC patterns were seen in 71% of the non-recurrent and in 35% of recurrent tumors. 67.7% tumors expressed IMP3 and all cases expressed E-Cadherin. The tumors with a higher percentage of destructive invasion showed higher IMP3 positivity and greater chances of recurrence, whereas tumors with higher percentage of pushing invasion showed lower IMP3 positivity and lesser chances of recurrence (p = 0.02). IMP3-negative tumors had lower odds of recurrence than IMP3-positive ones (p = 0.01). The patients with negative IMP3 staining had a significantly higher OS than those with IMP3 positive tumors (p = 0.01), regardless of the histologic patterns. Also, reduction in E-Cadherin staining in the metastatic site led to poor DFS (p = 0.016) and OS (p = 0.006). IMP3 may serve as a useful prognostic marker that can stratify patients of advanced stage, high-grade serous carcinomas into two distinct subsets: majority with early recurrence with an infiltrative pattern of invasion and IMP3 positivity particularly in the MP areas; and a smaller subset that do not show early recurrence having pushing borders and are IMP3 negative. Also, E-Cadherin showed significant decrease in expression in the metastatic site of the recurrent cases.

FOXC1 identifies basal-like breast cancer in a hereditary breast cancer cohort.

Breast cancers arising in the setting of the hereditary breast cancer genes BRCA1 and BRCA2 are most commonly classified as basal-like breast cancer (BLBC) or luminal breast cancer, respectively. BLBC is an aggressive subtype of breast cancer associated with liver and lung metastases and poorer prognosis than other subtypes and for which chemotherapy is the only systemic therapy. Multiple immunohistochemical markers are used to identify the basal-like subtype, including the absence of estrogen receptor alpha, progesterone receptor, and human epidermal growth factor receptor 2. Forkhead box C1 (FOXC1) has been identified as a specific marker expressed in BLBC in general breast cancer cohorts. We examined an institutional cohort of breast cancer patients with germline BRCA1 (n=46) and BRCA2 (n=35) mutations and found that FOXC1 expression on immunohistochemical staining is associated with BRCA1 vs BRCA2 mutations [30/46 vs. 6/35]. In BRCA1 mutant tumors, FOXC1 was expressed in 28/31 BLBC tumors and 2/13 non-BLBC tumors, In BRCA2 mutant tumors, FOXC1 was expressed in 5/5 BLBC tumors and 1/30 non-BLBC tumors. In cell culture models of BRCA1-mutant breast cancer, FOXC1 is associated with increased proliferation and may serve as a marker for sensitivity to PARP-inhibitor therapy with olaparib.

BRCA-mutated Invasive Breast Carcinomas: Immunohistochemical Analysis of Insulin-like Growth Factor II mRNA-binding Protein (IMP3), Cytokeratin 8/18, and Cytokeratin 14.

To evaluate the expression of insulin-like growth factor II mRNA-binding protein (IMP3), CK8/18, and CK14 in BRCA mutated and sporadic invasive breast carcinoma. Immunohistochemistry for IMP3, CK8/18, and CK14 was performed on 39 cases of invasive breast carcinomas with BRCA mutation (24 BRCA1, 14 BRCA2, and 1 dual BRCA1/BRCA2) and 54 cases of sporadic invasive breast carcinomas. The relationship between the IMP3, CK8/18, and CK14 and the tumor grade and molecular phenotypes were analyzed. IMP3, CK8/18, and CK14 positivity were present in 20 (51%), 22 (56%), and 14 (36%) of 39 BRCA-mutated breast carcinomas, and 11 (20%), 53 (98%), and 24 (44%) of 54 sporadic breast carcinomas respectively. The rates of IMP3 expression and absence of CK8/18 (44% versus 2%) in BRCA-mutated breast carcinomas was significantly higher than the sporadic breast carcinomas (p = 0.002 and p < 0.001). No significant difference was observed for CK14 among the two groups (p = 0.408). No significant difference was observed among BRCA1-related and BRCA2-related breast carcinomas in the immunoprofile for IMP3, CK8/18, and CK14. No significant correlation was identified between the expression of IMP3 and CK8/18 and the tumor grade in both BRCA-mutated and sporadic breast carcinomas (p > 0.05). In cases with luminal A and B phenotypes, the rates of expression of IMP3 and loss of CK8/18 were significantly higher in BRCA-mutated as compared to sporadic breast carcinoma (p < 0.001). In cases with basal-like phenotype, the absence of CK8/18 expression was significantly higher in BRCA-mutated breast carcinomas (54% versus 0%, p = 0.001), while no difference was observed for IMP3 expression (p = 0.435). Regardless of mutation type, histologic grade, or molecular phenotype, the absence of CK8/18 expression and presence of IMP3 expression are seen at much higher rate in BRCA mutated breast carcinomas.

Squamous cell carcinoma of the ovary arising from a mucinous cystic tumor of endocervical (müllerian) type.

Primary squamous cell carcinoma of the ovary is extremely rare. We studied a 58-year-old woman in whom a keratinizing squamous cell carcinoma of the ovary had arisen from a mucinous cystic tumor of endocervical (müllerian) type. The tumor was interpreted initially as a transitional cell carcinoma of the ovary with marked squamous differentiation, but there was no evidence of either transitional cell carcinoma or malignant Brenner tumor. Furthermore, features of dermoid cyst (mature cystic teratoma), endometriosis, or adenosquamous carcinoma were not seen. The mucinous columnar epithelial component was largely benign and only focally proliferative or borderline. As found typically in endocervical (müllerian) mucinous tumors, numerous polymorphonuclear leukocytes were seen in the stroma and the neoplastic mucinous epithelium.

Comparative analysis of size estimation by mapping and counting number of blocks with ductal carcinoma in situ in breast excision specimens.

CONTEXT: The size of ductal carcinoma in situ (DCIS) is a significant predictor of local tumor recurrence and is used for selection of patients for conservative versus aggressive therapy. A standardized method for size assessment is lacking. OBJECTIVE: To evaluate 2 commonly used methods for measurement of DCIS extent: one based on the distribution of the lesion in sequential series of sections (mapping method) and the other on the number of sections with DCIS (block method). DESIGN: Ninety-eight consecutive cases of DCIS, measuring at least 1.0 cm, were retrieved from our files. All specimens were serially sectioned along the long axis. The size of DCIS was calculated for each case by 2 different methods: (1) mapping method (average thickness of each slice x number of consecutive slices with DCIS) and (2) block method (number of blocks with DCIS x 0.3 cm). Additional calculations were performed by using 0.35, 0.4, and 0.5 cm as multiplication factors for the block method in order to improve concordance. RESULTS: The block method underestimated the size in 71 cases (72%) by 4.5% to 81.3% (mean, 33%). Using 0.4 cm as the multiplication factor improved concordance, while multiplying by 0.5 cm led to an overestimation of size. CONCLUSIONS: Assessment of DCIS size by the block method is inaccurate and underestimates size in most cases (72%), with an average reduction of 33%. Using 0.4 cm as the multiplication factor improves concordance. A standardized method for size estimation is necessary for effective patient management.

HER2 in well differentiated breast cancer: is testing necessary?

BACKGROUND: In addition to providing a timely and accurate diagnosis, pathologists routinely provide prognostic and predictive information to assist in the treatment of patients with invasive breast cancer. As our understanding of breast cancer at the molecular and genetic level improves, sophisticated new treatment options have become available to patients. The demonstrated improvements in disease-free and overall survival with the use of trastuzumab (Herceptin) has made HER2 testing a standard of care in the evaluation of patients with breast cancer. Specialized breast centers have accumulated sufficient experience to recognize that HER2 positive tumors tend to be of higher grade and to be estrogen receptor negative, whereas well-differentiated breast cancers rarely are HER2 positive. METHODS: To determine whether HER2 testing is necessary in well-differentiated breast cancer, we analyzed the frequency of HER2 positivity among 1,162 cases from 7 major breast centers or commercial laboratories in the United States and Europe. RESULTS: Well-differentiated breast cancers, defined by either nuclear grading or the Scarff-Bloom-Richardson system, rarely are HER2 positive (mean 1.6%, range 0-2.8%). CONCLUSIONS: Given the low rate of well differentiated HER2 positive tumors, falling within the range reported for false negative IHC tests for HER2, and the absence of published data demonstrating a beneficial effect of trastuzumab therapy in this subset of patients, HER2 testing should not be considered a standard of care for all patients with well-differentiated breast cancer.

Lobular intraepithelial neoplasia [lobular carcinoma in situ] with comedo-type necrosis: A clinicopathologic study of 18 cases.

The recent finding that lobular, and not ductal intraepithelial neoplasia (DIN) displays loss of E-cadherin expression has greatly facilitated the categorization of a large proportion of morphologically ambiguous intraepithelial neoplasias into ductal or lobular types. One reason for such morphologic ambiguity is the presence of comedo-type necrosis within an intraepithelial lesion that otherwise shows archetypal cytologic and architectural features of lobular intraepithelial neoplasia (LIN). The clinicopathologic features of 18 such cases are described in this report. These 18 cases of classic LIN were accumulated from the recent databases of 6 institutions. All cases, by definition, showed no expression of E-cadherin. The 18 patients, all women, were 41 to 85 years of age (mean 61.3). The lesions were initially identified in an excisional biopsy or mastectomy in 12 cases and in an incisional/core biopsy in the remaining 6 cases. An associated invasive carcinoma was present in 12 (67%) of 18 cases (7 classic lobular, 1 pleomorphic lobular, 1 ductal, 1 mixed lobular and ductal, 1 tubular, and 1 case with ductal and lobular carcinomas as separate foci). The average age of the 6 patients with pure LIN (ie, LIN without an invasive component (62.5 y) was not significantly different from the 12 patients in which there was an invasive component (60.7 y) (P = 0.78). The lesions had associated calcifications, typically within the necrotic foci, in 10 (55%) of 18 cases. Immunoreactivity for estrogen receptor, progesterone receptor (in >10% of lesional cells), and high-molecular weight keratin was present in 17/18 (94%), 15/18 (83%) and 17/18 (94%) of cases, respectively. Overexpression of HER2/neu, as assessed immunohistochemically, was absent in all 15 cases available for such evaluation. Foci of DIN, separate from the lobular lesions, were present in 6 (33%) of 18 cases. LIN with necrosis seems to occur at an older age than classic LIN, is commonly associated with invasive carcinoma and is significantly more frequently associated with lobular than ductal invasive carcinoma. When present without an invasive component, it may be mistaken for DIN 2 (grade 2 ductal carcinoma in situ). Although the necrosis suggests a ductal phenotype for these intraepithelial proliferations, architectural and cytologic features, high-molecular weight keratin[+], estrogen receptor[+], progesterone receptor[+], and human epidermal growth factor receptor 2 /neu[-] immunoprofile, frequent association with invasive lobular carcinoma, and lack of immunoreactivity for E-cadherin, strongly suggests that these lesions are within the morphologic spectrum of lobular neoplasia. Long-term follow-up studies are required to define the true natural history of these lesions. However, because classic LIN with necrosis is apparently rare in its pure form, reexcision is recommended when this lesion is detected in isolation in a core biopsy.

Polypoid endometriosis: a clinicopathologic analysis of 24 cases and a review of the literature.

We describe 24 cases of polypoid endometriosis, most of which were referred because of problems in differential diagnosis, particularly distinction from a low-grade müllerian neoplasm. The patients were 23 to 78 years (mean 52.5 years) of age. Seven patients were on unopposed estrogen, four on combined estrogen-progestin therapy, and one patient had a synchronous ovarian thecoma. The most common clinical presentations were a pelvic mass, vaginal polypoid masses, and large bowel obstruction. In some cases, the intraoperative findings suggested a neoplasm. Sites of involvement in order of frequency included colon, ovary, uterine serosa, cervical and/or vaginal mucosa, ureter, fallopian tube, omentum, bladder, paraurethral and paravaginal soft tissue, and retroperitoneum. Multiple sites were involved in seven cases. Five cases occurred within ovarian or extraovarian endometriotic cysts. The lesions ranged up to 14 cm in size and formed polypoid, pink, gray or tan, masses. On microscopic examination, the polypoid masses were composed of an admixture of endometriotic glands and stroma. A variety of glandular architectural patterns were observed, sometimes in combination, most commonly cystic and noncystic simple hyperplasia, but also simple or complex hyperplasia with atypia, disordered proliferative, and cystic atrophy. Various types of epithelial metaplasia (tubal, mucinous, squamous, papillary syncytial metaplasia) were common. Hemorrhage, fibrosis, prominent thick-walled blood vessels, hemosiderin-laden histiocytes, and decidual change were also present in some cases. Eighteen cases were associated with usual (nonpolypoid) endometriosis. In one case, polypoid endometriosis merged with a mucinous borderline tumor of endocervical-type. In all but two cases, polypoid endometriosis lacked periglandular stromal hypercellularity, stromal atypia, and intraglandular stromal papillae, helping distinguish it from adenosarcoma. Focal intraglandular stromal papillae were noted in two cases with focal mild periglandular stromal hypercellularity in one of them, but no stromal atypia was present in either case. Follow-up data in 17 patients indicated that 15 patients were alive without evidence of residual disease, 1 was alive with residual endometriosis, and 1 died of other causes. In conclusion, polypoid endometriosis is a rare manifestation of endometriosis that may be mistaken for a neoplasm on clinical, intraoperative, or pathologic assessment. Some cases may be attributable to exogenous hormones or hyperestrinism and, like conventional endometriosis, some may evolve into a premalignant or, rarely, a neoplastic lesion. The main lesion in the differential is a müllerian (mesodermal) adenosarcoma.

BRCA1 transactivates the cyclin-dependent kinase inhibitor p27(Kip1).

The p27(Kip1) is a member of the universal cyclin-dependent kinase inhibitor family. Previously, immunochemical analysis of a series of breast cancer cell lines demonstrated a correlation between the expression of p27(Kip1) and the breast cancer susceptibility gene BRCA1. BRCA1 has a number of activities including DNA repair, growth inhibition and as a transcription factor. Here we demonstrate that BRCA1 transactivates expression of p27(Kip1). This transactivation is dependent on the presence of a functional C-terminal transactivation domain. Promoter-deletion analysis identified the presence of a putative BRCA1-responsive element located at position -615 to -511 of the p27(Kip1) promoter. These results suggest that the transcriptional regulation of p27(Kip1) by BRCA1 may be a mechanism for BRCA1- induced growth inhibition.