Pleomorphic Lobular Carcinoma Research Articles

Pleomorphic Lobular Carcinoma In Situ Composed of Signet-Ring Cells Mimicking Ductal Carcinoma In Situ with A Papillary Pattern: A Case Report.

While some forms of invasive or in situ carcinoma of the breast may be partly composed of signet-ring cells, signet-ring cells rarely become a prominent feature of pleomorphic lobular carcinoma in situ (LCIS). We report a rare example of pleomorphic LCIS composed predominantly of signet-ring cells with a papillary pattern mimicking ductal carcinoma in situ (DCIS). A 58-year-old woman presented with a mass in the left breast detected by ultrasonography. Fourteen years previously, the patient underwent right breast-conserving surgery for invasive breast carcinoma of no special type. Ultrasonography revealed an irregular parallel, angular hypoechoic mass measuring 1.5 cm in the left breast. An ultrasound-guided core needle core biopsy was conducted. Microscopically, the lesion was composed of epithelial cells supported by a fibrovascular stroma. The majority (> 70%) of the lesional cells between the fibrovascular stalks showed signet-ring cell features. Some of the nuclei of the signet-ring cells showed intermediate-grade atypia. A mucicarmine stain showed intracytoplasmic mucin in the signet-ring cells. Immunohistochemistry for E-cadherin was negative in the tumor cells. After surgical excision, the final diagnosis was a pleomorphic LCIS. To our knowledge, there have been no previous reports of pleomorphic LCIS consisting primarily of signet-ring cells with a papillary pattern.

Automated feathered edge blood smear analysis: early diagnosis of carcinocythemia in a case of disseminated intravascular coagulation with multi-organ failure.

Carcinocythemia, known as the presence of circulating tumor cells in the peripheral blood, is difficult to detect when the carcinoma cells are minimally present. We describe a case of a 56-year-old patient presenting with disseminatedintravascular coagulation (DIC) and multiple organ failure. Despite initial suspicion of sepsis, a peripheral blood smear showed the presence of atypical cells, mainly located at the feathered edge, leading to a presumptive diagnosis of carcinocythemia of unknown primary origin. The presence of a high-fluorescent cell population detected by our hematology analyzer (Sysmex XN-9100) and immunohistochemical staining with pancytokeratin AE1/AE3 confirmed the carcinoma cell origin. The patient died 4 days after referral to our hospital. Postmortem examination revealed a pleomorphic lobular breast carcinoma (triple-negative, androgen receptor-negative). Given the clinical acuity of patients with carcinocythemia, early diagnosis is essential to guide management. This case underscores the importance of optimizing current workflows relying on complex flagging algorithms and enhanced digital imaging to aid in the early detection of such rare condition. When patients present with DIC of unknown origin and high fluorescent signals are detected on the hematology analyzer, carcinocythemia should actively be ruled out by extensive microscopic peripheral blood examination.

A histomorphological and immunohistochemical analysis of invasive lobular carcinoma of breast: A case series

Invasive lobular carcinoma (ILC) is the second most common special subtype of invasive breast carcinoma comprising 5–15%. ILC defines as invasive carcinoma comprising non-cohesive single-file linear pattern in fibrous stroma. The aim of the study was to evaluate the histomorphological features and immunohistochemical analysis of ILC. A total of 19 cases were encountered from March 2020 to February 2024 out of 129 breast cancers. The sociodemographic profiles and clinicopathological parameters of the patients were studied with special emphasis on their morphology and hormone receptor status. The mean age of patients is 42.8 years. Out of 19 cases, 84.2% showed feature of classic type, 5.2% of tubule-lobular, and 10.5% of pleomorphic lobular carcinoma. The majority of cases (63.2%) showed histologic Grade 2, and 10.5% showed Grade 3. On immunohistochemistry examination, 79% were estrogen receptor (ER) and progesterone receptor (PR) positive with 10.5% of cases was human epidermal growth factor receptor 2/neu (HER2/neu) positive. Our study showed higher cases of classic type ILC, mostly of histologic Grade 2; higher ER-PR receptor positivity and HER2/neu negativity.

Characteristics of Triple Negative Subtype Breast Cancer in Dr. Hasan Sadikin General Hospital for 5 Years (2019-2023): An Observational Study

Background: Triple-negative breast cancer has a percentage of 15% to 20% in breast cancer patients at the time of first diagnosis. Guidelines from St. Gallen guidelines, the American Society of Clinical Oncology, and the American College of Pathology state that triple-negative breast cancer is breast cancer with ER and PR expression <1%. As an aggressive subtype, outcomes are poor when compared with hormone receptor-positive. Methods: This research is an observational study. The research subjects in this study were triple-negative breast cancer patients in Dr. Hasan Sadikin General Hospital, Surgical Oncology division, West Java, Indonesia, from October 2018 - November 2023. There were 702 research subjects who would be studied. Characteristics of triple-negative breast cancer were taken from medical records. Results: The results showed that the average age of the subjects was 47 years. Based on histology, the most common was Invasive Carcinoma of no special type (86.75%), followed by Invasive lobular carcinoma (7.26%), medullary carcinoma (1.7%), micropapillary carcinoma (0.99%), metaplastic carcinoma (2.36%) and the least amount is Pleomorphic invasive lobular carcinoma (0.71%). The side of the breast affected is not significant, and the highest grade is 3. The involvement of lymph node metastases is due to aggressive tumor subtypes and lymphovascular invasion. Lymphovascular invasion is known to be a negative prognostic factor. It is a late stage for metastasis and local recurrence. Conclusion: Triple-negative breast cancer is breast cancer that has histopathological heterogeneity; most of the tumors are grade 3 and have significant metastases in regional lymph nodes. There is no significant relationship between grading and regional lymph node metastases. there is a significant relationship between lymphovascular invasion and regional lymph nodes metastases.

Comparison of Clinicopathological Features of Pleomorphic and Invasive Lobular Breast Carcinomas.

Accounting for about 15% of invasive lobular carcinomas and 1% of breast carcinomas, pleomorphic lobular carcinoma is known to be a rare histological subtype of invasive lobular carcinoma. Yet, it is more aggressive and produces a worse prognosis than other breast cancers. Ultimately, the present study compares the clinicopathological features of pleomorphic and invasive lobular breast carcinomas. In the study, we retrospectively evaluated the data of 262 patients with histological subtypes of classical and pleomorphic lobular cancers having been recruited for surgical operations. After resorting to Kolmogorov-Smirnov and Shapiro-Wilk tests to check the normality of distribution, the categorical and continuous variables were compared between the groups using the chi-square test and independent samples t test, respectively. In all analyses, we considered a P-value of <.05 to be statistically significant. Our findings revealed that the groups with lobular and pleomorphic groups significantly differed by Ki-67 value, estrogen receptor negativity, grade, multicentricity, multifocality, surgical margin positivity, completion mastectomy, and metachronous contralateral tumor (P < .05). We discovered that pleomorphic type was associated with higher grades, estrogen receptor negativity, and Ki-67 expression. The incidence of metachronous breast cancer was high in the pleomorphic group, which may be a noteworthy finding to be considered in follow-ups. In addition, the high rates of multicentricity and multifocality of tumors in the pleomorphic group may be associated with increased surgical margin positivity and a higher likelihood of mastectomy. In a nutshell, our findings may guide patients and surgeons regarding the type of intervention and reconstruction options to be adopted in prospective surgeries.

160 (PB-067) Poster - Risk of upstaging after a core biopsy diagnosis of classic, pleomorphic and non-classic lobular carcinoma in situ, a nationwide study

160 (PB-067) Poster - Risk of upstaging after a core biopsy diagnosis of classic, pleomorphic and non-classic lobular carcinoma in situ, a nationwide study

Metastatic Pleomorphic Lobular Carcinoma of the Breast to the Urinary Bladder: A Report of 10 Cases and Assessment of TRPS1 in the Differential Diagnosis With Plasmacytoid Urothelial Carcinoma.

Metastatic pleomorphic lobular carcinoma (MPLC) to the bladder is rare and has considerable histologic and immunohistochemical overlap with plasmacytoid urothelial carcinoma (PUC). To distinguish MPLC from PUC morphologically and immunohistochemically, including a newer marker, TRPS1. Ten MPLCs to the bladder were reassessed and stained with estrogen, progesterone, and androgen receptors; GATA3; keratin 5/6; HMWK; GCDFP-15; and TRPS1. Sixteen PUCs constituted controls. We studied 4 transurethral resections of bladder tumors and 6 biopsies from 10 women (median age, 69 years) who had breast cancer on average 15 years prior. Microscopic patterns included single cells and cords of cells (n = 4), nests/sheets of dyscohesive cells (n = 2), or both (n = 4). All tumors had cells with voluminous eosinophilic cytoplasm and eccentric nuclei mimicking PUC, and 7 of 10 tumors had signet ring cells. MPLCs were positive for estrogen (8 of 10), progesterone (3 of 7), and androgen receptors (4 of 10); GCDFP-15 (7 of 10); GATA3 (9 of 10); HMWK (7 of 8); and TRPS1 (7 of 10). No MPLCs stained for keratin 5/6 (n = 9). Of 16 PUCs, 2 showed faint and 2 demonstrated strong TRSP1 staining; 7 of 16 were negative for p63. MPLC to bladder often presents in patients with a remote history of breast cancer, exhibiting significant histologic and immunohistochemical overlap with PUC. Based on prior works and the current study, estrogen receptor (particularly SP-1), mammaglobin, and p63 help differentiate MPLC from PUC. Keratin 5/6 may aid in distinguishing a less frequent basal type PUC because it is typically negative in MPLC. Some PUCs express TRPS1. Caution should be exercised because immunophenotypes of these tumors greatly overlap, and ramifications of misclassification are major.

Motley and Immured-Lobular Carcinoma In situ Pleomorphic

Pleomorphic lobular carcinoma in situ represents as an exceptionally discerned, morphological subtype of lobular carcinoma in situ (LCIS). Neoplasm is contemplated to express a genetic and biological advancement of classic lobular carcinoma in situ and emerges as a direct precursor to invasive carcinoma breast. Initially scripted by Frost et al in 1996, pleomorphic lobular carcinoma in situ is contemplated as a morphologic variant of classic lobular carcinoma in situ.

Exploration of cancer associated fibroblasts phenotypes in the tumor microenvironment of classical and pleomorphic Invasive Lobular Carcinoma.

Multiplex immunofluorescence were performed on formalin fixed paraffin embedded tissues using Opal-7 color kit. The antibodies used for phenotyping CAFs were Pan CK (AE1/AE3), CD45, A-SMA, FAP, S100, Thy-1 with optimized dilutions. The images were acquired and analyzed using Vectra 3.0 imaging system and InForm software respectively. We studied 19 different CAFs colocalized phenotypes in the tumor, stroma and overall tissue compartments between classic and pleomorphic ILC. Total A-SMA+, A-SMA+FAP+S100+ and A-SMA+S100+ CAFs demonstrated higher densities in classic ILC cases while FAP+S100+ and S-100+ CAFs were increased in the pleomorphic subtype samples. Our study explores multiple CAFs phenotypes between classical and pleomorphic ILC. We showed that CAFs subset differ between Classic ILC and Pleomorphic ILC. A-SMA CAFs are more prevalent in the TME of classic ILCs whereas Pleomorphic ILCs are dominated by CAFs without A-SMA expression. This also iterates the importance of exploring this particular type of breast carcinoma in more detail, paving the way for meaningful translational research.

Lobular Neoplasia Diagnosed by MRI-Guided Breast Biopsy: Identifying Upgrade Rate to Malignancy and Outcomes of Clinical and Surgical Management.

The aim of this study was to determine surgical and clinical outcomes of lobular neoplasia (LN) diagnosed by magnetic resonance imaging (MRI) biopsy, including upgrade to malignancy, and to assess for characteristics associated with upgrade. A single-institution retrospective study, between 2013 and 2022, of patients with histopathological findings of LN via MRI-guided biopsy was performed using an institutional database and review of the electronic medical records. Decision for excision or surveillance was made by a multidisciplinary team per institutional practice. Patient demographics and imaging characteristics were summarized using descriptive analyses. Upgrade was defined as upgrade to cancer on surgical pathology for patients treated with excision or the development of cancer at the biopsy site during surveillance. The Wilcoxon rank-sum test and Fisher's exact test were used to compare features of the upgraded cohort with the remainder of the group. Ninety-four MRI biopsies diagnosing LN were included. Median age was 57 years (range 37-78years). Forty-six lesions underwent excision while 48 lesions were surveilled. The upgrade rate was 7.4% (7/94). Upgrades in the excised cohort consisted of pleomorphic lobular carcinoma in situ (LCIS; n=1), ductal carcinoma in situ (DCIS; n=3) and invasive lobular carcinoma (ILC; n=2), while one interval development of DCIS was observed at the site of biopsy in the surveillance cohort. No MRI or patient variables were associated with upgrade. In this contemporary cohort of MRI-detected LNs, the upgrade rate was low. Omission of surgery for MRI-detected LNs in carefully selected patients may be considered in a shared decision-making capacity between the patient and the treatment team. Larger cohorts are needed to determine factors predictive of upgrade risk.

Primary Mucinous Cystadenocarcinoma of the Breast Intermixed with Pleomorphic Invasive Lobular Carcinoma: The First Report of This Rare Association.

Primary mucinous cystadenocarcinoma (MCA) is a rare breast carcinoma subtype showing overlapping histopathological features with mucinous cystadenocarcinoma of the ovary and pancreas. Current literature data suggest a favorable prognosis of breast MCAs despite its immunoprofile usually revealing lack of expression of estrogen receptor, progesterone receptor and HER-2 and high Ki67. As far as we know, only 36 cases have been reported in the literature to date. Its ambiguous morpho-phenotypic profile makes histological diagnosis very challenging. It must be distinguished from typical mucin-producing breast carcinomas and, above all, metastases from the same histotype in other sites (ovary, pancreas, appendix). Herein, we report the case of a primary breast MCA occurring in a 41-year-old female with peculiar histological features.

Tumor-Infiltrating Lymphocytes and PD-L1 Expression in Pleomorphic Lobular Breast Carcinoma.

The prognostic and predictive role of stromal tumor-infiltrating lymphocytes (sTILs) is undetermined in pleomorphic invasive lobular cancer (pILC). The same applies for the expression of PD-1/PD-L1 in this rare breast cancer subtype. Here, we aimed to investigate the expression of sTILs and analyze the PD-L1 expression levels in pILC. Archival tissues from sixty-six patients with pILC were collected. The sTIL density was scored as a percentage of tumor area using the following cut-offs: 0%; <5%; 5-9%; and 10-50%. The PD-L1 expression was analyzed using IHC on formalin-fixed, paraffin-embedded tissue sections using SP142 and 22C3 antibodies. A total of 82% of the sixty-six patients were hormone receptor positive and 8% of cases were triple negative (TN), while 10% showed human epidermal growth factor receptor 2 (HER2) amplification. sTILs (≥1%) were present in 64% of the study population. Using the SP142 antibody, 36% of tumors demonstrated a positive PD-L1 score of ≥1%, and using the 22C3 antibody, 28% had a positive PD-L1 score of ≥1. There was no correlation between sTILs or PD-L1 expression and tumor size, tumor grade, nodal status, expression of estrogen receptor (ER), or amplification of HER2. Our data did not show any difference in survival between the three molecular subtypes of pILC with respect to sTILs and PD-L1 expression. This study shows that pILCs show some degree of sTILs and PD-L1 expression; however, this was not associated with a survival improvement. Additional large trials are needed to understand immune infiltration in lobular cancer, especially in the pleomorphic subtype.

ROLE OF SEROUS FLUID CYTOLOGY IN BOTH NON-MALIGNANT AND MALIGNANT LESIONS WITH EMPHASIS ON CYTOMORPHOLOGY OF RARE METASTATIC MALIGNANCIES TO SEROUS CAVITY

Context: Serous effusion cytology is an important investigation for diagnosis of neoplastic and non-neoplastic diseases. Malignant cells in serous uid cytology indicates advanced stage. To evaluate the utility of serous ui Aims: d cytology in differential diagnosis of malignant and nonmalignant serous effusions and to emphasize the cytomorphology of rare metastatic malignancies. The importance of cell block with immunocytochemistry for diagnostically challenging cases was also highlighted. T Settings and Design: his was a one year retrospective study in which cases were classied into malignant and non-malignant. Immunohistochemistry was performed on cell blocks of difcult to diagnose cases. Methods and Material: Total 356 serous uids (pleural, peritoneal and pericardial uids) were centrifuged, cytocentrifuged and stained with Papanicolaou and Giemsa. Clinical history, radiological ndings and other relevant parameters were noted. 184 cases were of pleural Results: uid, 168 of peritoneal uid and four were of pericardial uid. Lung malignancies and ovarian malignancies were the most common primary sites in pleural and peritoneal uids respectively. Out of 40 positive for malignancy cases, 22 were rst conrmed on cytology. Clinical diagnosis of Boerhaave's syndrome was conrmed on cytology. Rare presentations of metastasis of squamous cell carcinoma, pleomorphic lobular carcinoma and clear cell type renal cell carcinoma were diagnosed on cytology. Rare m Conclusions: etastatic malignancies to serous cavity pose diagnostic challenges on cytology. Both, cytopathologists and clinicians should be aware of these rare malignancies. A vigilant cytopathologist can identify malignant cells based on cytomorphological features and give accurate diagnosis with the help of ancillary tests and lead clinicians for further work up, evaluation and treatment of the patients

Abstract P6-04-16: ART: Automated Region segmentation of Tumor on HER2-stained breast cancer tissue

Abstract Background Computational pathology-based methods, eg, Quantitative Continuous Scoring (QCS) [Gustavson, SABCS 2020], are built to provide objective and quantitative methods to assess HER2 expression in breast cancer (BC). For accurate HER2 quantification, it is important to exclude non-invasive epithelium from analysis since HER2 overexpression could be more frequent in ductal carcinoma in situ (DCIS) and pleomorphic lobular carcinoma in situ (PLCIS) than in invasive BC [Lari, J Cancer 2011]. Generally, computational pathology-based approaches require experts to delineate the invasive BC regions of interest for analysis and exclude all benign/non-invasive epithelium. Developing a tool that delineates the invasive BC regions automatically without human intervention to avoid subjectivity of manual annotation by pathologists is ideal. We developed a novel, deep-learning–based system, called DualScaleNet, to perform Automated Region segmentation of Tumor (ART) by automatically identifying the invasive BC regions and excluding benign/non-invasive epithelium on HER2-stained digitized images. Identification and diagnosis of these regions, especially the in situ tumors are a challenge as they can mimic benign and invasive lesions causing wrong HER2 evaluation. Additional stains (eg, p63 for myoepithelial cells or laminin for basement membrane) are often required for diagnosis [Pinder, Mod Pathol 2010] but were not available for this study. Methods DualScaleNet works simultaneously on HER2-stained immunohistochemistry (IHC) image patches at 2 different resolutions. The target branch uses a higher resolution RGB image (0.5 μm/pixel) to learn accurate local details; the context branch uses a lower resolution image (4.0 μm/pixel) to incorporate more context in visual learning. The algorithm generates 4 output image layers representing probabilities of 4 classes: invasive tumor, ductal/lobular carcinoma in situ, benign epithelium, and other tissue. The final segmentation result is generated by assigning each image pixel the class with the largest probability value. The algorithm was trained using ground truth (GT) annotations generated by 5 pathologists using 6157 square field of views (FOVs), 200-500 μm in size. These FOVs were collected from 850 whole slide images (WSI), spanning 9 commercial BC sample cohorts stained with different HER2 assays and scanned by several versions of the Aperio AT2 scanner. The samples included a mixture of biopsies and resections and covered different BC histologies and HER2 staining intensities. To evaluate the reproducibility of tumor area detection by human pathologists, an interpathologist comparison in detection of invasive tumor regions was performed using 225 FOVs annotated by multiple pathologists. Results Analysis generated an average Dice/F1 Score of 81.6% among different pathologists for invasive cancer. On the same sample set (independent of the ART training set), the invasive cancer detection by the ART algorithm was on par with human pathologists, achieving a similar average Dice/F1 score of 80.7%. Conclusions Novel deep learning-based ART algorithm provides accurate segmentation of invasive cancer on HER2-stained IHC images. The performance was verified against the GT annotations provided by multiple pathologists. Since the algorithm is trained using annotations from multiple pathologists, it is not possible to generate higher accuracy with computational pathology than is achievable between independent pathologists. Importantly, the same WSI read by the ART will consistently output the exact same tumor region identification result thus removing the inherent human subjectivity and variability, while improving the turnaround time for analysis. This development serves as the necessary foundation upon which a computational pathology-based diagnostic can be built. Citation Format: Ansh Kapil, Anatoliy Shumilov, Philipp Wortmann, Sihem Khelifa, Jessica Chan, Michel Vandenberghe, Craig Barker, Mark Gustavson, Danielle Carroll, Hadassah Sade, Günter Schmidt. ART: Automated Region segmentation of Tumor on HER2-stained breast cancer tissue [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-04-16.

Abstract P2-23-11: Quantitative gene expression by RT-PCR in histologic subtypes of invasive breast carcinoma: an update in nearly one million cases

Abstract Background: Invasive ductal carcinoma (IDC) accounts for ~80% of all invasive breast carcinomas (IBC) with several histologic subtypes comprising the remainder of cases. Some histologic subtypes of IDC (such as tubular carcinoma) have been associated with better prognosis, while other subtypes (such as metaplastic and micropapillary) have been associated with poorer prognosis. Prior studies have shown patients with early stage, hormone-receptor positive IBC that have low Recurrence Score® (RS), as measured by the 21-gene Oncotype DX® (ODX) assay, have little benefit from chemotherapy. Here, we report our experience with the histologic subtypes of IDC and associated patterns of observed gene expression using ODX. Methods: All US samples submitted for IBC ODX between 2005 to 2021 were reviewed. Ductal carcinoma NOS (DC), tubular carcinoma (TC), cribriform carcinoma (CC), mucinous carcinoma (MUC), lobular carcinoma classic, solid or alveolar type (ILC), pleomorphic lobular carcinoma (PL), medullary/medullary-like carcinoma (MED), metaplastic carcinoma (MET), micropapillary carcinoma (MP), papillary carcinoma (PC) and solid papillary carcinoma (SPC) were included. Quantitative expression of 16 cancer-related genes was measured on a scale from 2 to 15 (relative to reference genes) where 1 unit increment is associated with ~2-fold change in expression. RS was calculated as published. Descriptive statistics for the RS, individual genes (ER, PR, HER2), and gene groups [invasion gene group (IGG) and proliferation gene group (PGG)] were obtained. Results: A total of 957,624 samples were included in this analysis with 85.4% DC, 9.7% ILC, 2.8% MUC, 0.5% TC, 0.4% PL, 0.4% PC, 0.3% MP, 0.2% CC, 0.2% MED, 0.1% SPC, and 0.02% MET. For all types, a wide continuous range of RS was noted. MET had the highest median RS, followed in decreasing order by MED, PL, DC &amp; ILC, TC, MUC, MP, CC, SPC, and PC. ER and PR were highest among PC and SPC. ER and PR were lowest among MED and MET. HER2 was highest among PC and TC and lowest among MED and MET. IGG was highest in MET and lowest in SPC. PGG was lowest for TC and highest for MED and MET. ER+/PR-/HER2- phenotype occurred more often in MED and PL. ER-/PR+/HER2- phenotype rarely occurred, but was most frequent in MED and MET. ER+/PR+/HER2+ accounted for 0.4% of our total sample. Conclusions: Here, we demonstrate histologic subtypes of IDC have a wide continuous range of RS. ODX assay may be used to further stratify patients with IDC and its histologic subtypes; however, further studies are needed to better understand the predictive capability of ODX in the histologic subtypes. Table 1. Quantitative gene expression by RT-PCR in histologic subtypes of invasive breast carcinoma Table 2. Biomarker profile in histologic subtypes of invasive breast carcinoma Citation Format: Nhu Thuy Can, Cynthia A. Flannery, Jess Hoag, Alekhya Akkunuri, Helen Bailey, Frederick Baehner. Quantitative gene expression by RT-PCR in histologic subtypes of invasive breast carcinoma: an update in nearly one million cases [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-23-11.

Abstract P2-21-07: Exploring spatial correlations in Breast invasive Lobular Carcinoma subtypes using a novel CAF multiplex immunofluorescence panel

Abstract Background: Recent advances in immunotherapy led to development of new technologies to identify topographical distributions and correlations in the tumor microenvironment, enabling a better understanding of the tumor immune landscape. Based on the 2019 WHO classification Invasive lobular carcinoma (ILC) has various histological presentations. The pleomorphic variant has been reported to be biologically different to the classical counterpart. Cancer associated fibroblasts (CAFs) secrete cytokines and growth factors aiding in tumor growth. CAFs have been shown to express alpha-smooth muscle actin (α-SMA), Thy1, fibroblast activation protein (FAP), S-100. IHC based studies have shown differences in CAFs subpopulation between ILC and IDC. Here, we explored different CAFs subpopulations between Pleomorphic and Classical ILC using multiplex immunofluorescence (mIF). Study design: Multiplex immunofluorescence (mIF) was performed on formalin-fixed paraffin-embedded (FFPE) tissue sections [(n=6, classic ILC; n=6 pleomorphic ILC)] stained with Opal 7-color Kit using an automated system. Sections were stained consecutively with Pancytokeratin, CD45, A-SMA, FAP, S100, Thy-1. Slides were scanned using the Vectra 3.0 spectral imaging system (PerkinElmer). Five tumor ROIs were examined with Phenochart (Akoya/PerkinElmer) viewer and subsequent images were analyzed to explore spatial distances of CK+ cells to the CAFs. Data was generated using InForm and Phenoptr softwares (Akoya Labs) as a median value. Statistical analysis data correlation was performed using SPSS version 24.0 (IBM Corp) Results: Twelve invasive lobular carcinomas cases were evaluated. All cases with classical features were nuclear grade 2 and all pleomorphic cases (n=6) were nuclear grade 3. Six were Luminal B, five were Luminal A and one case was triple negative invasive lobular carcinoma. We studied nineteen different phenotypes of CAFs in the tumor, stroma, and overall tissue compartments. We found statistically significant differences (p-value&amp;lt; 0.05) between the distances of CAFs from the tumor cells in classic and pleomorphic ILC in three phenotypes. The A-SMA+, A-SMA+/S100+ phenotypes were closer to the tumor cells in classic subtype and the S100 only phenotype was closer to the tumor cells in pleomorphic carcinomas. In addition, there were two other phenotypes namely A-SMA+/Thy-1+(closer to tumor cells in classic ILC) and FAP+/S-100+ (closer to tumor cells in pleomorphic ILC), which showed a trend of significance (Table 1) Discussion: TME studies in invasive breast lobular carcinoma have been primarily based on chromogenic IHC. Multiplex immunofluorescence quantifies cell phenotype’s densities and positions in different tissue compartments (tumor vs stroma vs total tissue). Knowing the proximity of an individual TME cells to the tumor cells, aids in pinpointing possible therapeutic targets. Fibroblast dysregulation in cancers, enhances their pro-tumorigenic and anti-tumorigenic potential. Due to their heterogeneity, they can express a wide array of markers. Identifying the full possibility of CAF subsets is one of the keys to discovering actionable targets. Our results showed Alpha- SMA positive, Alpha-SMA/S-100 positive, Alpha SMA/Thy-1 positive CAFs in closer proximity to the classic ILC tumor cells as compared to pleomorphic ILC. Additionally, S-100 positive and FAP/S-100 positive CAFs showed a closer proximity to tumor cells in the pleomorphic subtype. Based on these results we hypothesize that pleomorphic ILCs are closely associated with pro-tumorigenic CAFs as compared to classic ILCs. Larger datasets are needed to confirm this. In conclusion we utilized an objective approach to quantify, phenotype and spatially correlate each cell in the tumor microenvironment. This has helped identifying CAFs subsets that differs in the spatial correlation to tumor cells in ILC subtypes, which can be potential actionable targets. Table 1 Phenotypes of Cancer associated fibroblasts and their statistical correlation between classic vs pleomorphic invasive Lobular carcinomas. Citation Format: Harsh Batra, Renganayaki K. Pandurengan, Heladio P. Ibarguen, Salome A McAllen, Qingqing Ding, Aysegul Sahin, Ignacio Wistuba, Edwin Roger Parra, Maria Gabriela Raso. Exploring spatial correlations in Breast invasive Lobular Carcinoma subtypes using a novel CAF multiplex immunofluorescence panel [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-21-07.

Abstract B021: Use of wide field optical coherence tomography (WF-OCT) in margin assessment during breast conserving surgery (BCS) for ductal carcinoma in situ (DCIS)

Abstract Purpose: To assess the utility of a novel imaging technology for intraoperative margin assessment in breast conserving surgery (BCS) for ductal carcinoma in situ (DCIS). Background: The multi-focal nature of DCIS presents a challenge to ensuring negative margins during BCS. Routine methods for intraoperative margin assessment, such as specimen radiography, ultrasound, cavity margins, and touch prep cytology each have specific limitations, including operator skill, time delay, probe position, and specimen completeness. A more recent method, wide field optical coherence tomography (WF-OCT), enables real-time tissue visualization at up to 2 mm of depth with the ability to use image-based machine learning to identify regions of interest suspicious for residual malignancy. Methods: Two adult females with biopsy-proven DCIS and one with invasive carcinoma underwent BCS following routine surveillance mammography and were prospectively evaluated. Primary lesions were imaged intraoperatively with specimen radiography and a WF-OCT imaging device (OTIS, Perimeter Medical AI, Toronto, Canada); images from both modalities were read to identify potential residual malignancy, and additional tissue was excised as indicated. Permanent histopathology was compared to imaging results. Results: The first patient (76 y/o, BI-RADS 4B, 1.6 cm) underwent BCS and the excised sample was 4 x 3.7 x 3.2 cm. By radiography, the biopsy clip and localization reflector were within the specimen and margins appeared satisfactory; WF-OCT demonstrated residual disease at the inferior margin and additional tissue was excised. Permanent histology showed DCIS involvement of inferior primary margin; additional margin excision contained DCIS and was negative. The second patient (64 y/o, BI-RADS 4B, 1 cm) underwent BCS and the excised sample was 4 x 3.5 x 3.5. By radiography, the biopsy clip and reflector were within the specimen and margins appeared satisfactory; WF-OCT showed residual disease at the inferior and posterior margins and additional tissue was excised. Permanent histology demonstrated DCIS within 1 mm and pleomorphic lobular carcinoma in situ (LCIS) microns from primary inferior margin; the additional inferior sample was margin negative, and posterior sample contained pleomorphic LCIS and was margin negative. The last patient (76 y/o, BI-RADS 5, 1.9 x 1.9 x 1.7 cm) underwent BCS and the excised sample was 6.5 x 5.3 x 4.2 cm. By radiography, the biopsy clip and localization reflector were within the specimen and margins appeared satisfactory; WF-OCT showed residual disease at the lateral margin and also revealed occult DCIS not found on biopsy. Additional tissue was taken until margin clearance by WF-OCT. Permanent histology demonstrated DCIS to &amp;lt;1 mm of primary lateral margin; the additional excision contained DCIS and was margin negative. Conclusions: In this case series of 3 adult females undergoing BCS for breast carcinoma, WF-OCT was a beneficial adjunctive imaging modality to specimen radiography for margin assessment. Citation Format: Amelia B. Tower, Andrew Berkeley. Use of wide field optical coherence tomography (WF-OCT) in margin assessment during breast conserving surgery (BCS) for ductal carcinoma in situ (DCIS) [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr B021.

Clinical-Pathological Correlation of Breast Non-mass Enhancing Lesions

Abstract Introduction/Objective MRI imaging of breast is mainly reserved for screening high-risk individuals with occasional application in women bearing moderate or average risk. Areas showing enhancement in MRI without space-occupying mass are defined as non-mass enhancement (NME). As biopsy of NME lesion is rare encounter in clinical practice, thorough clinical-pathological investigation is warranted. Methods/Case Report 289 patients who underwent core biopsy for NME lesion(s) in our institution between 2011 to 2021 were included in this retrospective study. Pathological diagnoses were lumped into 3 categories, namely benign, precursor lesions (atypical ductal hyperplasia, atypical lobular hyperplasia, and lobular carcinoma in situ), and malignant lesions (ductal carcinoma in situ, pleomorphic lobular carcinoma in situ, and invasive carcinoma). The age distribution, MRI indications, and pathological diagnoses stratified by indications were studied. MRI patterns of NME lesions were compared between malignant versus benign lesions. Results (if a Case Study enter NA) Patient’s age ranges 25-79 yo (mean age 51.9 yo, median age 50 yo). Indications of MRI include high-risk screening (162 cases, 162/289, 56%), pre-operative staging (116 cases, 116/289, 40%), and problem-solving (11 cases, 11/289, 4%). There are 220 benign cases (220/289, 76%), 50 malignant cases (50/289, 17%), and 19 precursor lesions (19/289, 7%) in this study. There were 16 malignant cases identified in the high-risk group (16/162, 10%), 24 in the pre-operative staging group (24/116, 20.7%), and 2 in problem-solving group (2/11, 18.2%). Focal distribution is significantly associated with malignant lesions as compared to other patterns (linear, segmental, and regional) (Chi-square test, p&amp;lt;0.001). Conclusion High-risk screening is the major indication for biopsy NME lesions, followed by pre-operative staging, and problem-solving. Benign lesions are the predominant pathological findings of NME lesions, followed by malignant and then precursor lesions. Malignant lesions were mostly identified in high-risk group, followed by pre-operative staging and problem-solving group. Malignant lesions tend to assume the “focal distribution” than other MRI patterns.

The Clinicopathologic Features of 22 Cases With Primary Invasive Papillary Carcinoma of the Breast Identified in 1153 Cases With Invasive Breast Carcinoma: Single-Center Experience.

Invasive papillary carcinoma (IPC) of the breast is an uncommon histologic subtype with limited data in the literature. The aim of this study was to increase the evidence base by presenting clinicopathological findings of cases diagnosed as IPC. Hematoxylin and eosin sections and immunostaining of surgical excision specimens diagnosed as invasive breast carcinoma were re-evaluated, retrospectively. IPC was detected in 22 cases (1.9%), of which 7 (0.6%) had pure and 15 (1.3%) had mixed morphology. Histologic types accompanying IPC were: Invasive ductal carcinoma (IDC) (15/15); invasive micropapillary carcinoma (3/15); and pleomorphic lobular carcinoma (1/15). Patient ages ranged between 36 and 89 (median 56.5) and the tumor size from 8 to 70 mm (median 19 mm). The histologic grade was 3 in five cases, 2 in 13, and 1 in four cases. The nuclear grade was 3 in 10 cases and 2 in 12. The values of positivity for estrogen receptor, progesterone receptor, human epidermal growth factor receptor-2, and Ki-67 index indicated Luminal B phenotype in 16 (72.7%), triple-negative in 5 (22.7%), and Luminal A in 1 case (4.6%). Ductal carcinoma in situ was noted in 19 cases (86.4%). IPC was mostly detected as an accompanying carcinoma to IDC at postmenopausal ages and was mostly Luminal B phenotype with intermediate-to-high grade features.

Biomarker profile of invasive lobular carcinoma: pleomorphic versus classic subtypes, clinicopathological characteristics and prognosis analyses.

To compare the clinicopathologic features and prognosis of pleomorphic invasive lobular carcinoma (P-ILC) and classic ILC (C-ILC) according to the biomarker profile. A total of 667 C-ILCs and 133 P-ILCs between 2011 and 2021 were included. Clinicopathologic features and stromal tumor-infiltrating lymphocytes (sTILs) status were evaluated. P-ILCs were divided into subtypes based on ER/PR and HER2 expression. The overall survival and disease-free survival (DFS) of patients were compared among matched P-ILCs, C-ILCs, and invasive ductal carcinomas (IDCs) with biomarker subtypes. Compared to C-ILCs, P-ILCs had greater tumor sizes and stages, fewer ER-positive, more HER2-positive, triple negative (TN), and Ki-67 > 20% tumors (P < 0.05). P-ILCs were subdivided into ER+ (63.1%), HER2+ (21.1%) and TN (15.8%). ER+ P-ILCs were mainlyshowed trabecular and solidgrowth patterns. Apocrine and solid featureswere more strongly associated with HER2+ P-ILCs and TN-P-ILCs, respectively.The prognosis of each biomarker group (ER+, HER2+ and TN) differed by subtype. The P-ILC biomarker subtypes hadworse prognosis than the same subtypes in the IDC group, while there wasno difference between the P-ILC and the C-ILC counterparts. Solid variants of P-ILChad the worst prognosis. Bone was the most common metastatic site in ER+ P-ILCs and TN-P-ILCs. HER2+ P-ILCs tended to metastasize to the brain and liver. DFS of HER2+ P-ILCs and TN-P-ILCs were worse than that of ER+ P-ILCs. Lacking lobular carcinoma in situ and sTILs ≤ 10% were associated with worse survival of ER+ P-ILCs and TN-P-ILCs, respectively. For HER2+ P-ILCs, Ki-67 > 20% and sTILs ≤ 10% were significant factors for lower DFS. P-ILCs is an aggressive subtype of ILCs. Analyzing the prognostic factors of P-ILCs with heterogeneous morphological and biomarker characteristics is helpful for creating an individualized treatment.