Microinvasive lobular carcinoma arising in a benign phyllodes tumour - a short report and brief review of the literature.

Lobular carcinoma in situ (LCIS) with microinvasion is a rare entity which is rarely reported in the literature. We describe a case of microinvasive LCIS following excision of a fibroepithelial lesion. The lesion was graded as U3 and M3 on ultrasonography and mammography respectively, and on core needle biopsy was described as a fibroepithelial lesion with 'unusual features'. Microscopic examination revealed a fibroepithelial lesion focally colonised by florid E-cadherin negative LCIS with multiple foci of microinvasive classical lobular carcinoma, which lacked a myoepithelial layer on CK5 and S100 staining.

Expression of PD-L1 in breast invasive lobular carcinoma.

PURPOSE: The purpose of this study was to investigate the expression of PD-L1 in invasive lobular carcinoma (ILC) and to determine its implications. METHODS: Tissue microarrays were constructed for 101 cases of ILC, and immunohistochemical staining for PD-L1 (using 22C3, SP142, and SP263 antibodies) was performed to examine the correlation between staining results and clinicopathologic parameters. RESULTS: The positive cut-off values were defined as tumor cell (TC)≥1%, immune cell (IC)>0%, and IC≥1%. The range of PD-L1 TC positivity was 0.0-2.0%, with PD-L1 SP263 TC showing the highest positivity of 2.0%. The range of PD-L1 IC positivity was 0-21.8% for IC ≥ 1%, with PD-L1 22C3 IC showing the highest positivity. When PD-L1 IC was positive (IC≥1%), the highest antibody agreement was observed between SP263 and SP142 (OA = 93.1%), while the lowest agreement was observed between 22C3 and SP263 (OA = 73.3%, κ = 0.040). PD-L1 22C3 IC positivity (≥1%) was associated with high nuclear grade (p = 0.002), HER-2 positivity (p = 0.019), and pleomorphic type (p = 0.002). CONCLUSION: PD-L1 expression in ILC shows a low TC positivity rate (0-2%) with various antibody clones and a variable IC positivity rate (0-21.8%). Pleomorphic type ILC exhibits higher PD-L1 IC positivity.

Brystkreftmetastaser i urinblæren.

Background: Bladder cancer is usually of urothelial origin. Locoregional metastases to the bladder may occur. Distant metastases to the bladder are rare. Case presentation: We present a woman in her eighties diagnosed with breast cancer (infiltrating lobular carcinoma). Three years after her treatment (surgery and radiotherapy), she was referred to the department of urology with macroscopic haematuria and night sweats. She was diagnosed with kidney stones based on the results from CT scans, urine cytology and cystoscopy. A few months after the urological evaluation, the patient had increasing MUC1 (CA 15 - 3) levels. Radiological and gynaecological examination did not reveal metastases. Due to recurrent haematuria, the urological workup with cystoscopy and CT was repeated, which revealed bladder pathology. Histology from these changes showed metastases from breast cancer. Interpretation: Distant metastases to the bladder may be hard to detect. In this case, concurrent kidney stones made the diagnosis even more challenging.

CAR expression in invasive breast carcinoma and its effect on adenovirus transduction efficiency.

BACKGROUND: Breast cancer is the second leading cause of death in women, with invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC) as the two most common forms of invasive breast cancer. While estrogen receptor positive (ER+) IDC and ILC are treated similarly, the multifocality of ILC presents challenges in detection and treatment, worsening long-term clinical outcomes in patients. With increasing documentation of chemoresistance in ILC, additional treatment options are needed. Oncolytic adenoviral therapy may be a promising option, but cancer cells must express the coxsackievirus & adenovirus receptor (CAR) for adenoviral therapy to be effective. The present study aims to evaluate the extent to which CAR expression is observed in ILC in comparison to IDC, and how the levels of CAR expression correlate with adenovirus transduction efficiency. The effect of liposome encapsulation on transduction efficiency is also assessed. METHODS: To characterize CAR expression in invasive breast carcinoma, 36 formalin-fixed paraffin-embedded (FFPE) human breast tumor samples were assayed by CAR immunohistochemistry (IHC). Localization of CAR in comparison to other junctional proteins was performed using a multiplex immunofluorescence panel consisting of CAR, p120-catenin, and E-cadherin. ILC and IDC primary tumors and cell lines were transduced with E1- and E3-deleted adenovirus type 5 inserted with a GFP transgene (Ad-GFP) and DOTAP liposome encapsulated Ad-GFP (DfAd-GFP) at various multiplicities of infection (MOIs). Transduction efficiency was measured using a fluorescence plate reader. CAR expression in the human primary breast carcinomas and cell lines was also evaluated by IHC. RESULTS: We observed membranous CAR, p120-catenin and E-cadherin expression in IDC. In ILC, we observed cytoplasmic expression of CAR and p120-catenin, with absent E-cadherin. Adenovirus effectively transduced high-CAR IDC cell lines, at MOIs as low as 12.5. Ad-GFP showed similar transduction as DfAd-GFP in high-CAR IDC cell lines. Conversely, Ad-GFP transduction of ILC cell lines was observed only at MOIs of 50 and 100. Furthermore, Ad-GFP did not transduce CAR-negative IDC cell lines even at MOIs greater than 100. Liposome encapsulation (DfAd-GFP) improved transduction efficiency 4-fold in ILC and 17-fold in CAR-negative IDC cell lines. CONCLUSION: The present study demonstrates that oncolytic adenoviral therapy is less effective in ILC than IDC due to differences in spatial CAR expression. Liposome-enhanced delivery may be beneficial for patients with ILC and tumors with low or negative CAR expression to improve adenoviral therapeutic effectiveness.

Preoperative breast MR imaging influences surgical management in patients with invasive lobular carcinoma.

INTRODUCTION: The purpose of the study is to assess the role of preoperative magnetic resonance (MR) imaging on the surgical management of invasive lobular carcinoma (ILC) and to evaluate whether breast density and background parenchymal enhancement (BPE) influence surgical treatment. METHODS: This retrospective study was conducted on 56 patients who were diagnosed with ILC between 2014 and 2020. All patients had mammogram and ultrasound. Preoperative MRI was available in 34 patients. Age, menopausal status, breast density, BPE, multifocality/multicentricity and surgical treatment were collected. RESULTS: Mean pathological tumour size was 36.4 mm (range 5-140 mm). Dense breasts had larger tumours compared to non-dense breasts (P = 0.072). Of the 34 patients with MRI, 6 opted for mastectomy. Of the remaining 28 cases, MRI findings upgraded surgery to mastectomy in 54% (15/28) because mammogram/ultrasound underestimated tumour extent in 25% (7/28), or multifocal/multicentric disease was identified in 29% (8/28). Tumour size was underestimated by MRI in 7% (2/28). In the non-MRI subgroup, 64% (14/22) of patients underwent breast-conserving surgery, but 29% of them (4/14) required a second-stage mastectomy due to extensive margin involvement. There was no difference in mastectomy rate between patients with MRI (62%) and without MRI (55%) (P = 0.061). Tumour size correlation between MRI and histopathology demonstrated an excellent intraclass correlation coefficient (P < 0.001). Surgical treatment recommendation was not significantly impacted by breast density or BPE. CONCLUSION: Breast MRI improves surgical management of patients with ILC in providing additional diagnostic information often missed with standard imaging modalities, and without increasing mastectomy rate. Surgical treatment is not impacted by breast density or BPE.

ESR1 Fusions Invoke Breast Cancer Subtype-Dependent Enrichment of Ligand-Independent Oncogenic Signatures and Phenotypes.

Breast cancer is a leading cause of female mortality and despite advancements in personalized therapeutics, metastatic disease largely remains incurable due to drug resistance. The estrogen receptor (ER, ESR1) is expressed in two-thirds of all breast cancer, and under endocrine stress, somatic ESR1 mutations arise in approximately 30% of cases that result in endocrine resistance. We and others reported ESR1 fusions as a mechanism of ER-mediated endocrine resistance. ER fusions, which retain the activation function 1- and DNA-binding domains, harbor ESR1 exons 1 to 6 fused to an in-frame gene partner resulting in loss of the ER ligand-binding domain (LBD). We demonstrate that in a no-special type (invasive ductal carcinoma [IDC]-NST) and an invasive lobular carcinoma (ILC) cell line, ER fusions exhibit robust hyperactivation of canonical ER signaling pathways independent of estradiol or antiendocrine therapies. We employ cell line models stably overexpressing ER fusions with concurrent endogenous ER knockdown to minimize endogenous ER influence. Cell lines exhibited shared transcriptomic enrichment in pathways known to be drivers of metastatic disease, notably MYC signaling. Cells expressing the 3' fusion partners SOX9 and YAP1 consistently demonstrated enhanced growth and cell survival. ILC cells expressing the DAB2 fusion led to enhanced growth, survival, and migration, phenotypes not appreciated in the IDC-NST DAB2 model. Herein, we report that cell line activity is subtype-, fusion-, and assay-specific, suggesting that LBD loss, the fusion partner, and the cellular landscape all influence fusion activities. Therefore, it will be critical to assess fusion frequency in the context of the clinicopathology.

Triple-Negative Pleomorphic Lobular Carcinoma in a BRCA1 Mutation Carrier: A Case of Complete Pathological Response.

BACKGROUND Hereditary breast cancer arising in BRCA1-deficient patients is commonly diagnosed as invasive carcinoma of no special type (NST) with medullary features, while invasive lobular carcinoma (ILC) appears to be significantly under-represented in BRCA1 mutation carriers. We report a case of pleomorphic ILC arising in a 28-year-old woman harboring a germline BRCA1 c.3756_3759delGTCT p.(Ser1253Argfs*10) pathogenic variant. CASE REPORT A nulliparous 28-year-old woman with a family history of BRCA1 mutation presented to the symptomatic breast clinic with a several-week history of a left 80-mm breast lump. Core biopsy established a diagnosis of a poorly differentiated triple-negative breast cancer (TNBC) of pleomorphic lobular phenotype. Her clinical diagnosis was cT3, N0, M0, cStageIIB. The MDT recommended CT staging, MRI breast imaging and neoadjuvant chemotherapy (NACT). PET CT imaging showed no evidence of distant metastatic disease. The patient had a good radiological response to NACT with a FEC-T carboplatin regimen. Post-NACT imaging showed a residual cystic mass and the patient underwent a mastectomy and sentinel lymph node biopsy with plans for a delayed latissimus dorsi reconstruction following her adjuvant radiotherapy treatment. A complete pathological response was subsequently demonstrated without any evidence of metastatic disease. CONCLUSIONS This case is the first report of pleomorphic ILC with a triple-negative receptor status and a complete pathological response in a BRCA1 mutation carrier. Our study expands the heterogeneous spectrum of TNBC and contributes to a better understanding of the molecular genetic landscape that characterizes invasive pleomorphic lobular neoplasia.

Nomograms to predict the long-term prognosis for non-metastatic invasive lobular breast carcinoma: a population-based study.

Invasive lobular breast carcinoma (ILC) is one potential subset that "clinicopathologic features" can conflict with "long-term outcome" and the optimal management strategy is unknown in such discordant situations. The present study aims to predict the long-term, overall survival (OS) and cancer-specific survival (CSS) of ILC. The clinical information of patients with non-metastatic ILC was retrieved from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2020. A total of 31451 patients were enrolled and divided into the training cohort (n=22,017) and validation cohort (n=9434). The last follow-up was December, 31, 2020 and the median follow-up period was 99 months (1-203). Age, marriage, estrogen (ER) status, progesterone (PR) status, grade, tumor size, lymph node ratio (LNR) and combined summary (CS) stage were prognostic factors for both OS and CSS of ILC, whereas chemotherapy and radiation were independent protect factors for OS. The nomograms exhibited satisfactory discriminative ability. For the training and validation cohorts, the C-index of the OS nomogram was 0.765 (95% CI 0.762-0.768) and 0.757 (95% CI 0.747-0.767), and the C-index of the CSS nomogram were 0.812 (95% CI 0.804-0.820) and 0.813 (95% CI 0.799-0.827), respectively. Additionally, decision curve analysis (DCA) demonstrated that the nomograms had superior predictive performance than traditional American Joint Committee on Cancer (AJCC) TNM stage. The novel nomograms to predict long-term prognosis based on LNR are reliable tools to predict survival, which may assist clinicians in identifying high-risk patients and devising individual treatments for patients with ILC. Our findings should aid public health prevention strategies to reduce cancer burden. We provide two R/Shiny apps ( https://ilc-survival2024.shinyapps.io/osnomogram/ ; https://ilc-survival2024.shinyapps.io/cssnomogram/ ) to visualize findings.

Clipped Axillary Node as a Potential Surrogate for Overall Axillary Nodal Status in Inflammatory Breast Cancer Patients after Neoadjuvant Chemotherapy.

BACKGROUND: Axillary lymph node dissection is the current standard for management of the axilla in inflammatory breast cancer (IBC). The present study aims to determine whether the initially positive node identified by clip placement accurately represents the overall nodal status of axilla after neoadjuvant chemotherapy (NAC) in IBC. PATIENTS AND METHODS: A retrospective study was conducted on patients with IBC who underwent operation (2014-2023). For patients with IBC who had clip placement in a positive axillary node at diagnosis, operative notes, specimen radiographs, and pathology reports were reviewed to confirm final pathologic status of clipped nodes. RESULTS: In total, 92 patients with IBC (90 cN+) were identified (median age 54 years, 78% invasive ductal, 10% invasive lobular, and 12% mixed); 81 (90%) were biopsy-proven cN+, with a clip placed in the positive node for 62/81 (77%). All patients were treated with NAC and axillary surgery with median 19 (range 4-49) nodes removed. Among 28 (out of 56) patients with retrieved clipped nodes that were pathologically negative (ypN0), only 1 had an additional positive node with micrometastasis for a false negative rate of 4% (95% CI 1-19%). Conversely, 3/3 patients with isolated tumor cells (ITCs) only in the clipped node had additional axillary disease (ITCs in 1, macrometastasis in 2), and 20/23 (87%) of patients with pathologically positive clipped node (micrometastasis or greater) had additional positive nodes [19/20 (95%) with macrometastasis]. CONCLUSIONS: The clipped biopsy-positive axillary node in IBC accurately represented the post-NAC overall axillary nodal status. ITCs post-NAC should be considered positive as an indicator of additional nodes with metastasis.

Insights into E-Cadherin Impairment in CDH1-Unaltered Invasive Lobular Carcinoma: A Comprehensive Bioinformatic Study.

Invasive lobular carcinoma exhibits unique morphological features frequently associated with alterations in CDH1. Although some studies have identified abnormalities in adhesion factors other than E-cadherin, the molecular mechanisms underlying E-cadherin abnormalities in CDH1-unaltered invasive lobular carcinoma remain poorly understood. In this study, we investigated the molecular underpinnings of E-cadherin dysregulation in invasive lobular carcinoma in the absence of CDH1 gene alterations, using comprehensive bioinformatic analyses. We conducted a comparative study of CDH1-mutated and non-mutated invasive lobular carcinoma and evaluated the differences in mRNA levels, reverse-phase protein array, methylation, and miRNAs. We observed that invasive lobular carcinoma cases without CDH1 alterations exhibited a significantly higher incidence of the Claudin-low subtype (p < 0.01). The results of the reverse-phase protein array indicate no significant difference in E-cadherin expression between CDH1-mutated and non-mutated cases. Therefore, abnormalities in E-cadherin production also exist in CDH1 non-mutated invasive lobular carcinoma. Considering that there are no differences in mRNA levels and methylation status, post-translational modifications are the most plausible explanation for the same. Hence, future studies should focus on elucidating the mechanism underlying E-cadherin inactivation via post-translational modifications in CDH1 non-mutated invasive lobular carcinoma.

A Genomics-Driven Artificial Intelligence-Based Model Classifies Breast Invasive Lobular Carcinoma and Discovers CDH1 Inactivating Mechanisms.

Artificial intelligence (AI) systems can improve cancer diagnosis, yet their development often relies on subjective histologic features as ground truth for training. Herein, we developed an AI model applied to histologic whole-slide images using CDH1 biallelic mutations, pathognomonic for invasive lobular carcinoma (ILC) in breast neoplasms, as ground truth. The model accurately predicted CDH1 biallelic mutations (accuracy = 0.95) and diagnosed ILC (accuracy = 0.96). A total of 74% of samples classified by the AI model as having CDH1 biallelic mutations but lacking these alterations displayed alternative CDH1 inactivating mechanisms, including a deleterious CDH1 fusion gene and noncoding CDH1 genetic alterations. Analysis of internal and external validation cohorts demonstrated 0.95 and 0.89 accuracy for ILC diagnosis, respectively. The latent features of the AI model correlated with human-explainable histopathologic features. Taken together, this study reports the construction of an AI algorithm trained using a genetic rather than histologic ground truth that can robustly classify ILCs and uncover CDH1 inactivating mechanisms, providing the basis for orthogonal ground truth utilization for development of diagnostic AI models applied to whole-slide image. Significance: Genetic alterations linked to strong genotypic-phenotypic correlations can be utilized to develop AI systems applied to pathology that facilitate cancer diagnosis and biologic discoveries.

Surveillance Strategies After Primary Treatment for Patients with Invasive Lobular Carcinoma of the Breast: Method of Local Recurrence Detection After Breast-Conserving Surgery.

BACKGROUND: Invasive lobular carcinoma (ILC) is the second most common subtype of breast cancer. Although mammography is known to have low sensitivity for ILC, there are no data to guide the optimal surveillance after treatment. We explored surveillance strategies after breast-conserving surgery (BCS) for ILC and determined the proportion of imaging-detected recurrences versus interval cancers. METHODS: From an institutional database of 813 women, we retrospectively identified patients who underwent BCS for stage I-III ILC and subsequently had a recurrence. We categorized patients by surveillance strategy and determined the modality of recurrence detection. Interval cancer rates for local recurrences were compared across surveillance strategies using the Chi-square test. We evaluated overall survival with the log-rank test and a Cox proportional hazards model. RESULTS: We included 58 patients with ILC who had a recurrence after BCS. Of these, 22 (37.9%) had local recurrence, 27 (46.6%) had distant recurrence, and 9 (15.5%) had both local and distant recurrence. Most patients underwent routine mammographic surveillance (65.2%), with 19.6% having supplemental breast magnetic resonance imaging (MRI) and 15.2% having no surveillance. The interval cancer rate was significantly higher in the mammographic surveillance group compared with the MRI surveillance group (61.9% vs. 16.7%; p < 0.001). CONCLUSION: In this study of patients with recurrence after BCS for primary treatment of stage I-III ILC, we found that most local recurrences were not detected by surveillance mammography. These data support further investigation of supplemental imaging beyond mammography specifically for patients with ILC who undergo BCS.

Trajectory of Subsequent Breast Cancer Diagnoses in a Diverse Patient Cohort with Breast Atypia.

BACKGROUND: Proliferative breast atypical lesions, including atypical ductal hyperplasia (ADH) and lobular intraepithelial neoplasms (LIN), represent benign entities that confer an elevated risk of ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC). However, the timing of disease progression is variable and risk factors associated with the trajectory of disease are unknown. METHODS: Patients diagnosed with ADH or LIN from 1992 to 2017 at an academic center were identified. Early progression was defined as DCIS or IBC diagnosed within 5 years following the initial atypia diagnosis. Unadjusted cancer-free survival was estimated using the Kaplan-Meier method. Demographics, clinicopathologic features, and use of chemoprevention were compared between the early and late development groups. RESULTS: Overall, 418 patients were included-73.7% with ADH and 26.3% with LIN. Over a median follow up of 92.1 months, 71/418 (17.0%) patients developed IBC (57.7%) or DCIS (42.3%). Almost half (47.9%, 34/71) were diagnosed within 5 years of their initial atypia diagnosis, and 52.1% (37/71) were diagnosed after 5 years. Patient and atypia characteristics were not associated with rate of events or time to events. There was a trend of early events being more often ipsilateral (76.5% early vs. 54.1% late; p = 0.13) versus contralateral. CONCLUSIONS: In a large cohort of patients with breast atypia and long-term follow up, 17% experienced subsequent breast events, with approximately half of the events occurring within the first 5 years following the initial atypia diagnosis. Clinical features were not associated with the trajectory to subsequent events, supporting that atypia signals both local and overall malignancy risk.

Is staging breast magnetic resonance imaging for invasive lobular carcinoma worthwhile?

BACKGROUND: Invasive lobular carcinoma (ILC) is challenging to stage accurately using mammography (MG) and ultrasound (US) with undiagnosed ipsilateral and contralateral cancer resulting in poor patient outcomes including return to surgery. Our institution employs routine staging breast MRI in ILC for this reason. However, increased time for further imaging/biopsies contributes to patient anxiety and potentially delays definite management. We aimed to quantify the frequency of staging MRI-detected additional lesions requiring biopsy or follow-up, the added cancer detection rate and MRI prompted change in surgical management. METHODS: An observational study on staging breast MRI for newly diagnosed ILC at a tertiary Western Australian hospital from January 2019 to August 2022. Standardized 3T MRI protocol was performed, double read by unblinded fellowship-trained radiologists. Histopathology from biopsy, surgery, or first annual surveillance was the reference standard for additional MRI-detected lesions. RESULTS: One hundred ten MRI studies demonstrated 49 (45%) patients had at least one additional clinically significant MRI-detected lesion. Thirty-one patients had an additional ipsilateral lesion detected, of which 18 (58%) proved malignant; 14 (45%) multifocal and 4 (13%) multicentric ILC. Additional work-up of MRI-detected lesions averaged a 9-day delay to definitive surgery compared to patients with a negative or definitively benign MRI. MRI changed surgical planning in 11 of 110 cases from breast conservation surgery (BCS) to mastectomy and there were two contralateral cancers diagnosed. BCS reoperation rate was 11%. CONCLUSION: Staging MRI for ILC identifies clinically significant lesions in nearly half of patients, predominantly ipsilateral multifocal disease, without significant delay to definitive surgery.

Case report: Characterization of the immunologic and molecular landscape in a unique presentation of invasive lobular carcinoma with concurrent uterine carcinosarcoma treated with immunotherapy.

Invasive lobular breast cancer (ILC) is characterized by a relatively high risk for late recurrence and a unique metastatic pattern with an increased risk for metastasis to gynecologic organs and peritoneum. We present a unique case of recurrent ILC with metastasis to the abdominal peritoneum as well as the uterine myometrium and cervix. Treatment was complicated by the discovery of concomitant uterine carcinosarcoma. This patient was effectively treated with a combination of hormonal therapy for her metastatic ILC and a combination of chemotherapy and immunotherapy for uterine carcinosarcoma. Molecular evaluation revealed a characteristic CDH1 mutation within the ILC and a PI3KCA mutation within the uterine carcinosarcoma, both of which have been linked to epithelial-to-mesenchymal transitions. Examination of the tumor immune microenvironment revealed proportionally more cytotoxic NK cells. This robust immune infiltration may be an indicator of the response to immunotherapy observed in this tumor or a result of the metastatic breast cancer within the uterus. This report provides a characterization of the molecular and immunologic landscape in this case with metastatic ILC and uterine carcinosarcoma.

Spatial molecular profiling of mixed invasive ductal and lobular breast cancers reveals heterogeneity in intrinsic molecular subtypes, oncogenic signatures, and mutations.

Mixed invasive ductal and lobular carcinoma (MDLC) is a rare histologic subtype of breast cancer displaying both E-cadherin positive ductal and E-cadherin negative lobular morphologies within the same tumor, posing challenges with regard to anticipated clinical management. It remains unclear whether these distinct morphologies also have distinct biology and risk of recurrence. Our spatially resolved transcriptomic, genomic, and single-cell profiling revealed clinically significant differences between ductal and lobular tumor regions including distinct intrinsic subtype heterogeneity - e.g., MDLC with triple-negative breast cancer (TNBC) or basal ductal and estrogen receptor positive (ER+) luminal lobular regions, distinct enrichment of cell cycle arrest/senescence and oncogenic (ER and MYC) signatures, genetic and epigenetic CDH1 inactivation in lobular but not ductal regions, and single-cell ductal and lobular subpopulations with unique oncogenic signatures further highlighting intraregional heterogeneity. Altogether, we demonstrated that the intratumoral morphological/histological heterogeneity within MDLC is underpinned by intrinsic subtype and oncogenic heterogeneity which may result in prognostic uncertainty and therapeutic dilemma.

Additional confirmation of successful cell suspension fractionation of metastatic axillary node tissue.

We present herein an extension to our recently developed and published method termed "Fractionation of Nodal Cell Suspension" (FNCS). The method enables efficient subcellular fractionation into nuclear (N) and cytosolic (C) compartments of extremely fibrous and problematic metastatic axillary lymph node (mALN) tissue, using the entire nodule. For the purpose of the present study, a case of invasive lobular breast cancer (BC) patient with pT2N3aMx status and defined primary tumor markers (ERα 8, PR-B 8, and HER2 score 0) was available. Initially, the mALN tissue of this patient was analyzed by immunohistochemistry (IHC), and a positive correlation of nodal ERα, PR-B and HER2 biomarkers to those of the primary tumor was obtained. Subsequently, the mALN was FNCS fractionated into N and C, and Western blot (WB) analysis demonstrated a single band for ERα, PR-B and nuclear loading control (HDAC1) in nuclear, but not in the cytosolic compartments, confirming the efficiency of our fractionation protocol. At the same time, HER2 bands were not observed in either compartment, in accordance with HER2 negativity determined by IHC in both primary tumor and mALN tissue. In conclusion, by confirming the nuclear expression of ERα and PR-B biomarkers in metastatic loci, we demonstrate the purity of the FNCS-generated compartments - the protocol that offers a reliable tool for further analysis of nuclear versus cytosolic content in downstream analysis of novel biomarkers in the whole mALN of BC patients.

E-Cadherin Mutational Landscape and Outcomes in Breast Invasive Lobular Carcinoma.

Invasive lobular carcinomas (ILC) are characterized by the loss of E-cadherin expression and CDH1 gene inactivation. Diagnostic reproducibility for this tumor type is currently suboptimal and could be improved by a better understanding of its histomolecular and clinical heterogeneity. We have analyzed the relationship between the presence, type, or position of CDH1 mutations, E-cadherin expression, and clinicopathological features (including outcome) in a retrospective series of 251 primary ILC with a long follow-up (median: 9.5 years). The mutational status of E-cadherin gene (CDH1) was determined by RNA sequencing from frozen tumor samples. E-cadherin immunohistochemistry (IHC) was performed with antibodies directed against the intracellular domain (clone 4A2C7) and the extracellular domain (clone NCH38). IHC expression of p120 and ß-catenin was also assessed in E-cadherin diffusely positive cases. Three major patterns of E-cadherin membrane expression were identified by IHC, with good agreement between the 2 clones (overall concordance: 83.8%, Kappa 0.67): null/focal expression (≤10%) (72.8% of cases for 4A2C7 and 83.8% for NCH38), heterogeneous expression (11%-89%) (19.2% of cases for 4A2C7 and 6.9% for NCH38), and diffuse expression (≥90%) (8% of cases for 4A2C7 and 9.3% for NCH38). E-cadherin membranous expression, when present, was abnormal (incomplete labeling and/or reduced intensity). ILC with diffuse E-cadherin expression showed abnormal ß-catenin or p120-catenin staining in 21% of cases. Interestingly, these cases with diffusely expressed E-cadherin had a CDH1 mutation rate as high as the E-cadherin null/focal cases (∼70%) but were enriched in nontruncating mutations. Regarding CDH1 mutation location, intracytoplasmic domain mutations correlated with a divergent E-cadherin IHC phenotype between the 2 antibodies (4A2C7 ≤ 10%/NCH38 ≥ 10%). Clinico-pathological correlation analyses found that stromal amount (inversely correlated with tumor cellularity) and tumor-infiltrating lymphocytes were less abundant in ILC with E-cadherin null/focal cases. In addition, CDH1 truncating mutations were associated with radiohistologic size discordance and were identified in multivariate survival analysis as an independent poor prognosis factor in terms of metastasis risk and breast cancer-related mortality. Overall, our study highlights the importance of the precise mutational status of CDH1 in the clinical, radiological, histologic, and phenotypic expression of lobular carcinomas. These findings should be taken into account in future attempts to improve diagnostic criteria or methods for ILC, as well as for clinicobiological studies dedicated to this tumor type.

A Late Recurrent Metastatic Breast Cancer Mimicking Primary Pancreatic Cancer: Case Report.

Metastasis to the pancreas from malignant tumors is a rare event, representing only 1% to 2% of all pancreatic neoplasms. They occur in 2 different clinicopathological settings: as a manifestation in widespread metastatic disease or as an isolated mass in the pancreas. We report the case of a 41-year-old woman who had a history of invasive lobular breast cancer treated with radical surgery, chemotherapy, and radiotherapy. After 21 years of total remission, she presented for severe lower back pain with jaundice, nausea, and loss of 9 kg in 3 months. Abdominal computed tomography demonstrated a hyper vascularized, irregular solid lesion of 2.6 cm × 2.1 cm in the head of the pancreas with discreet biliary duct dilatation and coelio-mesenteric enlarged lymph nodes measuring 2 cm. The diagnosis of pancreatic metastasis from a lobular breast carcinoma was made by percutaneous biopsy of pancreatic lesion. The multidisciplinary committee decided a palliative treatment. The patient received chemotherapy. The take home message from his case is that we should keep in mind the hypothesis of a solitary metastasis to the pancreas, when the pancreatic lesion develops in a patient who had a clinical history of previous neoplasm especially in those which is known to potentially metastasize to pancreas.