Pleomorphic lobular carcinoma of the breast: molecular pathology and clinical impact

Molecular Classification of Breast Cancer

Breast carcinomas classified based on traditional morphologic assessment provide useful prognostic information. Although morphology is still the gold standard of classification, recent advances in molecular technologies have enabled the classification of these tumors into four distinct subtypes based on its intrinsic molecular profile that provide both predictive and prognostic information. This article describes the association between the different molecular subtypes with the histologic subtypes of breast cancer and illustrates how these subtypes may affect the appearance of tumors on imaging studies.

Triple-negative breast lobular carcinoma: a luminal androgen receptor carcinoma with specific ESRRA mutations

Primary triple-negative invasive lobular breast carcinomas (TN-ILCs), which do not express hormone receptors and HER2 at diagnosis, are rare and poorly known. In this study, we analyzed the largest TN-ILC series ever reported in the literature, in comparison to phenotypically similar breast tumor subtypes: triple-negative invasive ductal carcinoma (TN-IDC) and hormone receptor-positive invasive lobular carcinoma (HR + ILC). All primary TN-ILCs registered in our database between 2000 and 2018 (n = 38) were compared to tumors from control groups, matched by stage and Elston/Ellis grade, with regard to clinical, pathologic, and immunohistochemical characteristics. A comparative molecular analysis (whole-exome and RNA sequencing using next-generation technology) was also performed. We found that TN-ILC patients were older than those with HR + ILC (P = 0.002) or TN-IDC (P < 0.001). Morphologically, TN-ILCs had aggressive phenotypes, with more pleomorphism (P = 0.003) and higher nuclear grades than HR + ILCs (P = 0.009). Immunohistochemistry showed that TN-ILCs less frequently expressed basal markers (CK5/6, EGFR and SOX10) than TN-IDCs (P < 0.001), while androgen receptor (AR) positivity was more prevalent (P < 0.001). Survival curves analysis did not show differences between TN-ILC and TN-IDC patients, while overall and distant metastasis-free survival were significantly worse compared to those with HR + ILCs (P = 0.047 and P = 0.039, respectively). At a molecular level, we found that TN-ILCs had particular transcriptomic profiles, characterized by increased AR signaling, and associated with frequent alterations in the PI3K network and ERBB2. Interestingly, whole-exome analysis also identified three specific recurrent ESRRA hotspot mutations in these tumors, which have never been described in breast cancer to date and which were absent in the other two tumor subtypes. Our findings highlight that TN-ILC is a unique aggressive breast cancer associated with elderly age, which belong to the luminal androgen receptor subtype as determined by immunohistochemistry and transcriptomic profiling. Moreover, it harbors specific molecular alterations (PI3K, ERBB2 and ESRRA) which may pave the way for new targeted therapeutic strategies.

Comprehensive Review of Molecular Mechanisms and Clinical Features of Invasive Lobular Cancer

Invasive lobular carcinoma (ILC) accounts for 10% to 15% of breast cancers in the United States, 80% of which are estrogen receptor (ER)-positive, with an unusual metastatic pattern of spread to sites such as the serosa, meninges, and ovaries, among others. Lobular cancer presents significant challenges in detection and clinical management given its multifocality and multicentricity at presentation. Despite the unique features of ILC, it is often lumped with hormone receptor-positive invasive ductal cancers (IDC); consequently, ILC screening, treatment, and follow-up strategies are largely based on data from IDC. Despite both being treated as ER-positive breast cancer, querying the Cancer Genome Atlas database shows distinctive molecular aberrations in ILC compared with IDC, such as E-cadherin loss (66% vs. 3%), FOXA1 mutations (7% vs. 2%), and GATA3 mutations (5% vs. 20%). Moreover, compared with patients with IDC, patients with ILC are less likely to undergo breast-conserving surgery, with lower rates of complete response following therapy as these tumors are less chemosensitive. Taken together, this suggests that ILC is biologically distinct, which may influence tumorigenesis and therapeutic strategies. Long-term survival and clinical outcomes in patients with ILC are worse than in stage- and grade-matched patients with IDC; therefore, nuanced criteria are needed to better define treatment goals and protocols tailored to ILC's unique biology. This comprehensive review highlights the histologic and clinicopathologic features that distinguish ILC from IDC, with an in-depth discussion of ILC's molecular alterations and biomarkers, clinical trials and treatment strategies, and future targets for therapy. IMPLICATIONS FOR PRACTICE: The majority of invasive lobular breast cancers (ILCs) are hormone receptor (HR)-positive and low grade. Clinically, ILC is treated similar to HR-positive invasive ductal cancer (IDC). However, ILC differs distinctly from IDC in its clinicopathologic characteristics and molecular alterations. ILC also differs in response to systemic therapy, with studies showing ILC as less sensitive to chemotherapy. Patients with ILC have worse clinical outcomes with late recurrences. Despite these differences, clinical trials treat HR-positive breast cancers as a single disease, and there is an unmet need for studies addressing the unique challenges faced by patients diagnosed with ILC.

Lobular carcinoma in situ: diagnostic criteria and molecular correlates

Lobular neoplasia (LN) is an atypical proliferation of small, dyscohesive epithelial cells within the terminal duct lobular unit (TDLU), with or without pagetoid extension and encompasses both lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH). LN is a non-obligate precursor of invasive breast carcinoma and the diagnosis of LN confers an increased risk of invasive carcinoma development, compared to the general population. Diagnostic challenges arise in the accurate classification of LCIS into classic, pleomorphic and florid subtypes, in distinguishing between LCIS and ductal carcinoma in situ (DCIS) and in the appropriate use and interpretation of E-cadherin immunohistochemistry. Due to the paucity of robust data on the natural history of LCIS, and hence its clinical significance, the management is often pragmatic rather than entirely evidence-based and requires a multidisciplinary approach. In this review, we discuss the clinicopathologic and molecular features of LCIS and address the key challenges that arise in the diagnosis and management of LCIS.

Deep learning-enabled breast cancer hormonal receptor status determination from base-level H&E stains

For newly diagnosed breast cancer, estrogen receptor status (ERS) is a key molecular marker used for prognosis and treatment decisions. During clinical management, ERS is determined by pathologists from immunohistochemistry (IHC) staining of biopsied tissue for the targeted receptor, which highlights the presence of cellular surface antigens. This is an expensive, time-consuming process which introduces discordance in results due to variability in IHC preparation and pathologist subjectivity. In contrast, hematoxylin and eosin (H&E) staining—which highlights cellular morphology—is quick, less expensive, and less variable in preparation. Here we show that machine learning can determine molecular marker status, as assessed by hormone receptors, directly from cellular morphology. We develop a multiple instance learning-based deep neural network that determines ERS from H&E-stained whole slide images (WSI). Our algorithm—trained strictly with WSI-level annotations—is accurate on a varied, multi-country dataset of 3,474 patients, achieving an area under the curve (AUC) of 0.92 for sensitivity and specificity. Our approach has the potential to augment clinicians’ capabilities in cancer prognosis and theragnosis by harnessing biological signals imperceptible to the human eye.

Determination of estrogen receptor status (ERS) in breast cancer tissue requires immunohistochemistry, which is sensitive to the vagaries of sample processing and the subjectivity of pathologists. Here the authors present a deep learning model that determines ERS from H&E stained tissue, which could improve oncology decisions in under-resourced settings.

Triple-negative pleomorphic lobular carcinoma and expression of androgen receptor: Personal case series and review of the literature

Pleomorphic lobular carcinoma (PLC) is a histological variant of invasive lobular carcinoma (ILC) and is associated with worse prognosis than classical ILC. It exhibits a greater degree of cellular atypia and pleomorphism and is occasionally accompanied with apocrine morphology. We investigated the immunohistochemical characteristics of samples from 31 Japanese patients with PLC to elucidate the clinicopathological characteristics of PLC including androgen receptor (AR) immunoreactivity. The surrogate molecular subtypes were luminal A-like, luminal B-like, luminal B-like/HER2, HER2-type, and triple-negative in 5, 4, 3, 5, and 14 cases, respectively. AR was positive in 92.8% (13/14) of the triple-negative PLC cases and 100% (10/10) of the non-triple-negative PLC cases. Disease-specific survival was worse in patients with histological grade 3 PLCs than in those with histological grade 2 PLCs (p = 0.007). However, there was no significant difference in the progression-free survival between the two groups (p = 0.152). No other clinicopathological characteristics were associated with prognosis. These results reveal that PLC exhibits various surrogate molecular subtypes and that the triple-negative subtype frequently expresses AR. The observed molecular apocrine differentiation implicates that triple-negative PLC can be categorized into the luminal AR subtype. Furthermore, AR-targeted therapy might be useful for patients with triple-negative PLC.

The Oncogenic Potential of the Centromeric Border Protein FAM84B of the 8q24.21 Gene Desert

FAM84B is a risk gene in breast and prostate cancers. Its upregulation is associated with poor prognosis of prostate cancer, breast cancer, and esophageal squamous cell carcinoma. FAM84B facilitates cancer cell proliferation and invasion in vitro, and xenograft growth in vivo. The FAM84B and Myc genes border a 1.2 Mb gene desert at 8q24.21. Co-amplification of both occurs in 20 cancer types. Mice deficient of a 430 Kb fragment within the 1.2 Mb gene desert have downregulated FAM84B and Myc expressions concurrent with reduced breast cancer growth. Intriguingly, Myc works in partnership with other oncogenes, including Ras. FAM84B shares similarities with the H-Ras-like suppressor (HRASLS) family over their typical LRAT (lecithin:retinal acyltransferase) domain. This domain contains a catalytic triad, H23, H35, and C113, which constitutes the phospholipase A_1/2 and O-acyltransferase activities of HRASLS1-5. These enzymatic activities underlie their suppression of Ras. FAM84B conserves H23 and H35 but not C113 with both histidine residues residing within a highly conserved motif that FAM84B shares with HRASLS1-5. Deletion of this motif abolishes FAM84B oncogenic activities. These properties suggest a collaboration of FAM84B with Myc, consistent with the role of the gene desert in strengthening Myc functions. Here, we will discuss recent research on FAM84B-derived oncogenic potential.

Adjuvant chemotherapy could not bring survival benefit to HR-positive, HER2-negative, pT1b-c/N0-1/M0 invasive lobular carcinoma of the breast: a propensity score matching study based on SEER database

BACKGROUND

The benefit of adjuvant chemotherapy in invasive lobular carcinoma (ILC) is still unclear. The objective of the current study was to elucidate the effectiveness of adjuvant chemotherapy in hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, pT1b-c/N0-1/M0 ILC.

METHODS

Based on Surveillance, Epidemiology, and End-Results (SEER) database, we identified original 12,334 HR-positive, HER2-negative, pT1b-c/N0-1/M0 ILC patients, who were then divided into adjuvant chemotherapy group and control group. End-points were overall survival (OS) and breast cancer-specific mortality (BCSM). Aiming to minimize the selection bias of baseline characteristics, Propensity Score Matching (PSM) method was used.

RESULTS

In a total of 12,334 patients with HR-positive, HER2-negative, pT1b-c/N0-1/M0 ILC, 1785 patients (14.5%) were allocated into adjuvant chemotherapy group and 10,549 (85.5%) into control group. Used PSM, the 1785 patients in adjuvant chemotherapy group matched to the 1785 patients in control group. By Kaplan-Meier survival analyses, we observed no beneficial effect of adjuvant chemotherapy on OS in both original samples (P = 0.639) and matched samples (P = 0.962), however, ineffective or even contrary results of adjuvant chemotherapy on BCSM both in original samples (P = 0.001) and in matched samples (P = 0.002). In both original and matched multivariate Cox models, we observed ineffectiveness of adjuvant chemotherapy on OS (hazard ratio (HR) for overall survival = 0.82, 95% confidence interval (CI) [0.62-1.09]; P = 0.172 and HR = 0.90, 95%CI [0.65-1.26]; P = 0.553, respectively), unexpectedly promoting effect of adjuvant chemotherapy on BCSM (HR = 2.33, 95%CI [1.47-3.67]; P = 0.001 and HR = 2.41, 95%CI [1.32-4.39]; P = 0.004, respectively). Standard surgery was beneficial to the survival of patients. Lymph node metastasis was detrimental to survival and radiotherapy brought survival benefit in original samples, but two issues had unobvious effect in matched samples.

CONCLUSION

In this study, adjuvant chemotherapy did not improve survival for patients with HR-positive, HER2-negative pT1b-c/N0-1/M0 ILC.

Rare epithelial breast cancer: surgery and adjuvant therapy

Breast cancer is a heterogenous disease, exhibiting a wide range of morphological phenotypes shaping its prognosis and clinical course. However, optimal management of rarer breast cancer subtypes is often undefined and controversial in literature due to the lack of large studies and randomised trials. This review aims to discuss the treatment of 13 rare epithelial subtypes, focussing on surgery and adjuvant therapies.

FAM84B promotes prostate tumorigenesis through a network alteration

Background:

The aim of this study was to investigate the contributions of FAM84B in prostate tumorigenesis and progression.

Methods:

A FAM84B mutant with deletion of its HRASLS domain (ΔHRASLS) was constructed. DU145 prostate cancer (PC) cells stably expressing an empty vector (EV), FAM84B, or FAM84B (ΔHRASLS) were produced. These lines were examined for proliferation, invasion, and growth in soft agar in vitro. DU145 EV and FAM84B cells were investigated for tumor growth and lung metastasis in NOD/SCID mice. The transcriptome of DU145 EV xenografts (n = 2) and DU145 FAM84B tumors (n = 2) was determined using RNA sequencing, and analyzed for pathway alterations. The FAM84B-affected network was evaluated for an association with PC recurrence.

Results:

FAM84B but not FAM84B (ΔHRASLS) increased DU145 cell invasion and growth in soft agar. Co-immunoprecipitation and co-localization analyses revealed an interaction between FAM84B and FAM84B (ΔHRASLS), suggesting an intramolecular association among FAM84B molecules. FAM84B significantly enhanced DU145 cell-derived xenografts and lung metastasis. In comparison with DU145 EV cell-produced tumors, those generated by DU145 FAM84B cells showed a large number of differentially expressed genes (DEGs; n = 4976). A total of 51 pathways were enriched in these DEGs, which function in the Golgi-to-endoplasmic reticulum processes, cell cycle checkpoints, mitochondrial events, and protein translation. A novel 27-gene signature (SigFAM) was derived from these DEGs; SigFAM robustly stratifies PC recurrence in two large PC populations (n = 490, p = 0; n = 140, p = 4e⁻¹¹), and remains an independent risk factor of PC recurrence after adjusting for age at diagnosis, Gleason scores, surgical margin, and tumor stages.

Conclusions:

FAM84B promotes prostate tumorigenesis through a complex network that predicts PC recurrence.

Outcomes of pleomorphic lobular carcinoma versus invasive lobular carcinoma

PURPOSE

Pleomorphic lobular carcinoma (PLC) is a rare histologic variant of invasive lobular carcinoma (ILC) that has been associated with worse clinical outcomes than classic ILC. Owing to its rarity, high-volume studies of its clinical characteristics and prognosis are lacking. The purpose of this study was to use a large, contemporary cancer database to investigate the clinical characteristics and survival outcomes for patients with PLC.

METHODS

The National Cancer Database (NCDB) was queried for women with cT1-4N1-3M0 breast cancer with either ILC or PLC histology having received definitive surgical therapy. Chi-squared analysis was performed to determine differences between the cohorts. Kaplan-Meier analysis evaluated overall survival (OS) between all patients and between patients when stratifying by age and subtype. Cox proportional hazards modeling determined variables associated with OS.

RESULTS

A total of 115,260 patients met the study criteria; of these, 114,859 (99.6%) had ILC, while 401 (0.4%) had PLC. A greater proportion of patients with PLC had T3-4 and node-positive disease, and were more likely to have ER- and HER2+ disease. PLC histology was associated with worse OS on both univariate and multivariate analysis (p < 0.001). PLC was associated with poorer OS in subgroups that were T3-4/N+ (but not T1-2N0) disease and ER+ (but not ER-) cancers, but not by HER2 status.

CONCLUSIONS

Patients with PLC, who were more likely to have ER- and HER2+ disease, experienced worse OS than patients with ILC, which may be limited to patients with more advanced clinical stage and ER + disease. Further work is needed to determine the optimal treatment for this more aggressive form of breast cancer.

A comparison of the imaging features of pleomorphic and classical invasive lobular carcinoma

PURPOSE

Pleomorphic invasive lobular carcinoma (pILC) is a distinct morphological variant of ILC with a poorer prognosis than classical ILC (cILC). The aim of this study was to ascertain whether the conventional imaging appearances of the two entities differ.

METHODS

A single-center retrospective review of conventional imaging was undertaken in 150 consecutive patients with histopathologically confirmed ILC (38 pILC; 112 cILC) between April 2010 and July 2015. Mammographic and sonographic findings were evaluated using the BI-RADS lexicon by a radiologist blinded to pathology, and the findings in the two groups were compared. The degree of discrepancy between imaging and pathological sizing in the two groups was evaluated.

RESULTS

Lesions were mammographically occult in 11% of pILC and 14% of cILC (p = 0.56). On mammography, skin or trabecular thickening and microcalcification were commoner in pILC than cILC (13% vs. 1%, p < 0.01; 25% vs. 5%, p < 0.01). Architectural distortion was more frequent in cILC than pILC (26% vs. 9%, p = 0.01). On ultrasound, pILC more frequently exhibited mixed echogenicity (28% vs. 13%; p = 0.04), skin thickening, subcutaneous or parenchymal edema (8% vs. 0%; p = 0.02), echogenic surrounding fat (33% vs. 9%; p < 0.01), and posterior acoustic enhancement (10% vs. 1%; p = 0.02) than cILC. CILC was more frequently manifested as a focal area of altered echogenicity (24% vs. 8%; p = 0.04). Mean elastography stiffness was higher for pILC (174.8 vs. 124.6 kPa; p = 0.02). Imaging-pathological size disparity was similar for both subtypes.

CONCLUSION

There are differences in the imaging features between pILC and cILC which reflect the more aggressive nature of pILC.

Pancreatic metastasis from invasive pleomorphic lobular carcinoma of the breast: a rare case report

Background

Invasive pleomorphic lobular carcinoma (PLC) is an aggressive subtype of invasive lobular carcinoma of the breast, which has its own histopathological and biological features. The metastatic patterns for PLC are distinct from those of invasive ductal carcinoma. In addition, pancreatic metastasis from PLC is extremely rare.

Case presentation

We report a rare case of a 48-year-old woman presenting with clinical gastrointestinal symptoms and pancreatic metastasis of PLC. The pancreatic tumor was composed of pleomorphic tumor cells arranged in the form of solid sheets and nests and as single files, with frequent mitotic figures, nucleolar prominence, high nuclear to cytoplasmic ratio and loss of cohesion. The malignant cells were positive for p120 (cytoplasmic) and GATA3 and negative for estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, E-cadherin, gross cystic disease fluid protein 15 and mammaglobin, which indicated a lobular carcinoma phenotype of the breast.

Conclusions

To the best of our knowledge, this is one of the few reported cases in the literature of pancreatic metastasis of invasive lobular carcinoma of the breast, of which the definitive diagnosis was obtained only after surgery. Rare metastasis sites should be considered, particularly, when a patient has a medical history of PLC.

Invasive Pleomorphic Lobular Histology is an Adverse Prognostic Factor on Survival in Patients with Breast Cancer

Invasive pleomorphic lobular carcinoma (IPLC) is defined to be an uncommon and different subtype of classical invasive lobular carcinoma (ILC). This special variant is characterized by significant cytological atypia and pleomorphism which differs from the cytological uniformity of ILC. IPLC has been shown to have some poor prognostic factors such as axillary node metastasis and higher histological grade which may lead to poor clinical courses including a short relapse time, increased risk of recurrence and a decreased survival. The aim of this study is to investigate the clinicopathological characteristics and prognosis of IPLC in comparison with ILC and also to evaluate if IPLC is a different clinical entity compared to ILC. A total number of 4418 breast cancer patients treated between 1996 and 2015 in Hacettepe University Cancer Institute, were retrospectively analyzed. Among 4418 patients, 210 were diagnosed with ILC and 23 patients diagnosed with pure IPLC. In this present study, clinicopathological characteristics, disease free survival (DFS) and overall survival (OS) of patients with ILC and IPLC were compared. This study design is one of the rare face to face comparison of pure IPLC and ILC. Patients with IPLC had an increased rate of higher histologic grade, extracapsular extension, lymphovascular invasion and lower percentage of hormone positivity than those of patients with ILC. During the follow-up time, IPLC group experienced 4 cases (17.3%) of recurrence, 5 cases (21.7%) of death and 2 cases (8.7%) of progression in 3 metastatic patients compared to that of 27 cases (12.9%) of recurrence, 29 cases (13,8%) of death and 14 cases (6.7%) of progression in 19 metastatic patients in the ILC group. Patients with IPLC had a worse DFS and OS duration than patients with ILC (P = 0.02 for OS, P = 0.04 for DFS). In conclusion, IPLC is a different and a special breast cancer subtype. This study suggests that IPLC is a distinct clinical entity with an advanced stage and more aggressive clinical course. Patients with IPLC reveal poorer prognostic factors such as higher histological grade, relative lower percentages of hormone positivity, and increased rate of recurrences resulting in poor clinical outcomes and worse survival. Nowadays, it is observed that current treatment methods for IPLC do not seem as successful as in ILC and failed to be effective. Thence, individual therapies including more aggressive surgery and adjuvant or neoadjuvant chemotherapy even in the earlier stages of breast cancer should be performed for this distinct variant.

Upregulation of FAM84B during prostate cancer progression

Although the FAM84B gene lies within chromosome 8q24, a locus frequently altered in prostate cancer (PC), its alteration during prostate tumorigenesis has not been well studied. We report here FAM84B upregulation in DU145 cell-derived prostate cancer stem-like cells (PCSLCs) and DU145 cell-produced lung metastases compared to subcutaneous xenograft tumors. FAM84B protein was detected in bone metastases and primary PCs. Nanostring examination of 7 pairs of tumor adjacent normal and PC tissues revealed elevations in FAM84B mRNA levels in all carcinomas. Furthermore, through analysis of FAM84B expression using large datasets within the Gene Expression Omnibus and OncomineTM database, we demonstrate significant increases in FAM84B mRNA in 343 primary PCs versus 181 normal tissues, and elevations in the FAM84B gene copy number (GCN) in 171 primary PCs versus 61 normal tissues. While FAM84B was not detected at higher levels via immunohistochemistry in high grade (Gleason score/GS 8-10) tumors compared to GS6-7 PCs, analyses of FAM84B mRNA and GCN using datasets within the cBioPortal database demonstrated FAM84B upregulation in 12% (67/549) of primary PCs and 18% (73/412) of metastatic castration resistant PCs (mCRPCs), and GCN increases in 4.8% (26/546) of primary PCs and 26% (121/467) of mCRPCs, revealing an association of the aforementioned changes with CRPC development. Of note, an increase in FAM84B expression was observed in xenograft CRPCs produced by LNCaP cells. Furthermore, FAM84B upregulation and GCN increases correlate with decreases in disease free survival and overall survival. Collectively, we demonstrate a novel association of FAM84B with PC tumorigenesis and CRPC progression.

Expression of Lipid Metabolism-Related Proteins Differs between Invasive Lobular Carcinoma and Invasive Ductal Carcinoma

We comparatively investigated the expression and clinical implications of lipid metabolism-related proteins in invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) of the breast. A total of 584 breast cancers (108 ILC and 476 IDC) were subjected to tissue microarray and immunohistochemical analysis for lipid metabolism-related proteins including hormone-sensitive lipase (HSL), perilipin A, fatty acid binding protein (FABP)4, carnitine palmitoyltransferase (CPT)-1, acyl-CoA oxidase 1, and fatty acid synthetase (FASN). HSL, perilipin A, and FABP4 expression (all p < 0.001) differed significantly: HSL and FABP4 were more frequently present in ILC, whereas perilipin A was more frequently detected in IDC. Among all invasive cancers, HSL and FABP4 were highly expressed in luminal A-type ILC (p < 0.001) and perilipin A in luminal A-type IDC (p = 0.007). Among luminal B-type cancers, HSL and FABP4 were more highly expressed in ILC (p < 0.001). Univariate analysis found associations of shorter disease-free survival with CPT-1 positivity (p = 0.004) and acyl-CoA oxidase 1 positivity (p = 0.032) and of shorter overall survival with acyl-CoA oxidase 1 positivity (p = 0.027). In conclusion, ILC and IDC exhibited different immunohistochemical lipid metabolism-related protein expression profiles. Notably, ILC exhibited high HSL and FABP4 and low perilipin A expression.

Uroplakin II Expression in Breast Carcinomas Showing Apocrine Differentiation: Putting Some Emphasis on Invasive Pleomorphic Lobular Carcinoma as a Potential Mimic of Urothelial Carcinoma at Metastatic Sites

Uroplakin II antibody is exclusively specific for urothelial carcinoma. Nonurothelial carcinoma has not been reported to be immunoreactive for uroplakin II. In the present study, we hypothesized that breast carcinoma showing apocrine differentiation, such as invasive pleomorphic lobular carcinoma (IPLC) and apocrine carcinoma (AC), stains positive for uroplakin II. We identified 6 cases of IPLC between 2000 and 2014 by searching a computerized pathological database. We randomly selected 10 cases of each classic invasive lobular carcinoma (cILC) and AC and five cases of apocrine metaplasia (AM) that coexisted in a surgically resected breast carcinoma specimen. Immunohistochemistry was performed for uroplakin II, GATA3, CK7, CK20, and other representative markers positive for urothelial carcinoma. All cases of IPLC, AC, and AM, except those of cILC, showed immunoreactivity for uroplakin II. Poorly differentiated urothelial carcinoma sometimes shows similar morphology to IPLC with the following immunophenotype: CK7+, CK20−, GATA3+, and uroplakin II+. In the present study, this immunophenotype was observed in all the cases of IPLC and AC. Therefore, when studying metastatic, poorly differentiated carcinoma showing the aforementioned immunophenotype, we should consider the possibility of it being IPLC in addition to metastatic urothelial carcinoma.

Molecular Classification of Breast Carcinoma: From Traditional, Old-Fashioned Way to A New Age, and A New Way

Breast carcinoma comprises a group of diseases with specific clinical, histopathologic and molecular properties. Traditional classification use morphology to divide tumors into separate categories with differing behavior and prognosis. However, there are limitations of traditional classification systems, and new molecular methods are expected to improve classification systems. Molecular subtypes of breast carcinomas have been characterized in the last 11 years, and have been studied extensively. Much of the information accumulated in recent years, and molecular taxonomy seems to be still developing and undergoing change. The main question is whether new molecular techniques such as gene expression profiling will be accepted as gold standard in determining breast cancer subtypes, and whether molecular classification is useful in specific subtypes of breast cancer as it is in ductal carcinoma (nonspecific type). In addition, critical review of the literature reveals major problems such as poor definition, lack of reproducibility and lack of quality control in current molecular techniques and classifications. Therefore, current molecular approaches are not yet used in routine clinical practice and treatment guidance since they are immature and can even lead to incorrect assessment.

When is excision necessary for atypical lobular hyperplasia and lobular carcinoma in situ?

SUMMARY This management perspective briefly covers the histology and molecular features of lobular in situ neoplasia and provides an in-depth discussion of the need for surgical excision if lobular in situ neoplasia is diagnosed on core-needle biopsy. The management of lobular in situ neoplasia found on core-needle biopsy has been an area of recent study with varying results. Emerging data suggest that low-risk patients with a limited extent of isolated classic lobular in situ neoplasia found on core-needle biopsy may not require subsequent surgical excision. However, high-risk patients, those with extensive lobular in situ neoplasia, or other high-risk lesions noted on core-needle biopsy likely benefit from surgical excision. Most authors recommend surgical excision when pleomorphic lobular carcinoma in situ is found on core-needle biopsy due to its higher association with invasive carcinoma. However, the natural history of this more recently described variant of lobular carcinoma in situ is not fully defined, and the clinical management of pleomorphic lobular carcinoma in situ on excisional biopsy is yet to be determined.

Pleomorphic lobular carcinoma of the breast: a morphologically and clinically distinct variant of lobular carcinoma

Pleomorphic lobular carcinoma is an uncommon variant of lobular carcinoma, characterized by significant cytologic atypia that contrasts with the low pleomorphism of classical lobular carcinoma. It accounts for approximately 1% of all epithelial breast malignancies. In addition to its pleomorphism, it is characterized by aggressive behavior and shortened patient survival. Although the morphologic features of pleomorphic lobular carcinoma are well described, it often eludes accurate pathologic characterization. Some controversy surrounds the pathogenesis of pleomorphic lobular carcinoma; however, it is now considered a well-defined variant of invasive lobular carcinoma. Pleomorphic lobular carcinoma shares molecular alterations with classical lobular carcinoma, such as alterations in the gene CDH1 on chromosome band 16q22 that results in changes in E-cadherin protein function. The aggressive biology of pleomorphic lobular carcinoma relates to the acquisition of genetic alterations typical of high-grade ductal carcinoma, such as overexpression of HER2/neu and c-myc.

Invasive pleomorphic lobular carcinoma of the breast: clinicopathologic characteristics and prognosis compared with invasive ductal carcinoma

PURPOSE

Invasive pleomorphic lobular carcinoma (IPLC) is a very rare and distinct morphological variant of invasive lobular carcinoma (ILC), characterized by nuclear atypia and pleomorphism contrasted with the cytologic uniformity of ILC. This study evaluated clinicopathologic characteristics and prognosis of IPLC compared with invasive ductal carcinoma (IDC).

METHODS

We retrospectively reviewed the medical records of 35 patients with IPLC and 6,184 patients with IDC, not otherwise specified. We compared the clinicopathologic characteristics, relapse-free survival (RFS) and disease specific survival (DSS) of patients who were surgically treated between January 1997 and December 2010.

RESULTS

Patients with IPLC presented at an older age with larger tumor size, worse histologic grade, higher rates of N3 stage, more multifocal/multicentric tumors, and more nipple-areolar complex involvement than those of patients with IDC. During the follow-up period, the IPLC group experienced five cases (14.3%) of disease recurrence and three cases (8.6%) of disease specific mortality compared with 637 cases (10.4%) of recurrence and 333 cases (5.4%) of disease specific mortality in the IDC group. Univariate analysis using the Kaplan-Meier method revealed that the IPLC group showed a significantly poorer prognosis than that of the IDC group (RFS, p=0.008; DSS, p<0.001). However, after adjusting for clinicopathologic factors, a multivariate analysis showed no statistical differences in RFS (p=0.396) and DSS (p=0.168) between the IPLC and the IDC groups.

CONCLUSION

Our data suggest that patients with IPLC present with poor prognostic factors such as large tumor size, poor histologic grade and advanced stage at diagnosis. These aggressive clinicopathologic characteristics may result in poor clinical outcomes. Although our study could not link IPLC histology to poor prognosis, considering the aggressive characteristics of IPLC, early detection and considerate treatment, including proper surgical and adjuvant intervention, could be helpful for disease progression and survival.

Molecular classification of breast cancer: is it time to pack up our microscopes?

Breast cancer is a heterogeneous disease. The traditional classification uses morphology to divide tumours into distinct categories with differing prognosis and behavior. Despite providing high quality data cheaply, it has limitations and hence there has been a hope that the new molecular methods may help to refine the classification systems. Much has been learned in the last few years however, the molecular taxonomy is still in evolution and likely to change over the coming years. Whether the molecular classification is as useful for special subtypes of breast cancers as it has been for ductal carcinoma, no special type, remains to be determined.

Discussion on common data analysis strategies used in MS-based proteomics

Current proteomics technology is limited in resolving the proteome complexity of biological systems. The main issue at stake is to increase throughput and spectra quality so that spatiotemporal dimensions, population parameters and the complexity of protein modifications on a quantitative scale can be considered. MS-based proteomics and protein arrays are the main players in large-scale proteome analysis and an integration of these two methodologies is powerful but presently not sufficient for detailed quantitative and spatiotemporal proteome characterization. Improvements of instrumentation for MS-based proteomics have been achieved recently resulting in data sets of approximately one million spectra which is a large step in the right direction. The corresponding raw data range from 50 to 100 Gb and are frequently made available. Multidimensional LC-MS data sets have been demonstrated to identify and quantitate 2000-8000 proteins from whole cell extracts. The analysis of the resulting data sets requires several steps from raw data processing, to database-dependent search, statistical evaluation of the search result, quantitative algorithms and statistical analysis of quantitative data. A large number of software tools have been proposed for the above-mentioned tasks. However, it is not the aim of this review to cover all software tools, but rather discuss common data analysis strategies used by various algorithms for each of the above-mentioned steps in a non-redundant approach and to argue that there are still some areas which need improvements.

Invasive Lobular Carcinomas Do Not Express Basal Cytokeratin Markers CK5/6, CK14 and CK17

The expression of basal cytokeratin markers CK5/6 in breast carcinomas has been associated with high histological grade and poor clinical outcome. A previous study has shown that CK5/6 can be detected in up to 17% of invasive lobular carcinomas (ILC). Here we study the expression of three basal cytokeratin markers (CK5/6, CK14, and CK17) in 53 ILC cases diagnosed by histology and lack of E-cadherin expression. Among them, 42 were classic lobular carcinomas, 6 were tubular-lobular carcinoma, and 5 were pleomorphic lobular carcinomas. There was no significant difference among these three groups in patients’ age, tumor size, uni- and multi-focality, expression of ER and PR, lymphovascular invasion, perineural invasion and lymph node metastasis. The only statistically different factor was HER2 over-expression, which was observed only in pleomorphic ILC (P = 0.0073). None of the 53 cases expressed CK5/6, CK14 or CK17; and 51/53 cases expressed luminal markers CK8 and CK18, and the two negative cases were both classic lobular carcinoma, with positivity for ER and PR. In conclusion, all 53 cases of ILC failed to show expression by any of the three basal CK markers, suggesting that very few ILC will demonstrate a basal phenotype when assessed by immunohistochemistry (IHC). More studies are needed to investigate molecular classification in lobular carcinoma of the breast.

Breast cancer precursors revisited: molecular features and progression pathways

Increasingly more coherent data on the molecular characteristics of benign breast lesions and breast cancer precursors have led to the delineation of new multistep pathways of breast cancer progression through genotypic-phenotypic correlations. It has become apparent that oestrogen receptor (ER)-positive and -negative breast lesions are fundamentally distinct diseases. Within the ER-positive group, histological grade is strongly associated with the number and complexity of genetic abnormalities in breast cancer cells. Genomic analyses of high-grade ER-positive breast cancers have revealed that a substantial proportion of these tumours harbour the characteristic genetic aberrations found in low-grade ER-positive disease, suggesting that at least a subgroup of high-grade ER-positive breast cancers may originate from low-grade lesions. The ER-negative group is more complex and heterogeneous, comprising distinct molecular entities, including basal-like, HER2 and molecular apocrine lesions. Importantly, the type and pattern of genetic aberrations found in ER-negative cancers differ from those of ER-positive disease. Here, we review the available molecular data on breast cancer risk indicator and precursor lesions, the putative mechanisms of progression from in situ to invasive disease, and propose a revised model of breast cancer evolution based on the molecular characteristics of distinct subtypes of in situ and invasive breast cancers.

The molecular underpinning of lobular histological growth pattern: a genome-wide transcriptomic analysis of invasive lobular carcinomas and grade- and molecular subtype-matched invasive ductal carcinomas of no special type

Invasive lobular carcinoma (ILC) is the most frequent special type of breast cancer. The majority of these tumours are of low histological grade, express hormone receptors, and lack HER2 expression. The pleomorphic variant of ILCs (PLCs) is characterized by atypical cells with pleomorphic nuclei and is reported to have an aggressive clinical behaviour. Expression profiling studies have demonstrated that classic ILCs preferentially display a luminal phenotype, whereas PLCs may be of luminal, HER2 or molecular apocrine subtypes. The aims of this study were two-fold: to determine the transcriptomic characteristics of lobular carcinomas and to define the genome-wide transcriptomic differences between classic ILCs and PLCs. To define the transcriptomic characteristics of ILCs, minimizing the impact of histological grade and molecular subtype on the analysis, we subjected a series of grade- and molecular subtype-matched ILCs and invasive ductal carcinomas (IDCs) to genome-wide gene expression profiling using oligonucleotide microarrays. Hierarchical clustering analysis demonstrated that ILCs formed a separate cluster and a supervised analysis revealed that 5.8% of the transcriptionally regulated genes were significantly differentially expressed in ILCs compared to grade- and molecular subtype-matched IDCs. ILCs displayed down-regulation of E-cadherin and of genes related to actin cytoskeleton remodelling, protein ubiquitin, DNA repair, cell adhesion, TGF-beta signalling; and up-regulation of transcription factors/immediate early genes, lipid/prostaglandin biosynthesis genes, and cell migration-associated genes. Supervised analysis of classic ILCs and PLCs demonstrated that less than 0.1% of genes were significantly differentially expressed between these tumour subtypes. Our results demonstrate that ILCs differ from grade- and molecular subtype-matched IDCs in the expression of genes related to cell adhesion, cell-to-cell signalling, and actin cytoskeleton signalling. However, classic ILCs and PLCs are remarkably similar at the molecular level and should be considered as part of a spectrum of lesions.