Literature review on the bilateral occurrence of invasive lobular breast cancer.

Historically, it has been believed that invasive lobular carcinomas (ILC) occur more frequently bilaterally compared to other invasive subtypes, with estimates ranging between 20% and 29%. This study aims to determine if this historical perspective still holds true. A comprehensive literature review was conducted to examine the bilateral occurrence of lobular carcinoma using various imaging methods. Additionally, the role of magnetic resonance imaging (MRI) in detecting contralateral carcinomas was also investigated. A comprehensive search was conducted in the MedLine database on the PubMed platform, resulting in 307 articles published between January 1, 2014, and January 1, 2023. Various selection criteria were applied to identify articles relevant to the research question. After careful assessment, eight articles remained that met the eligibility criteria, all of which provided level-three evidence and were therefore included in the literature review. A total of 599 patients were included in this review, comprising a total of 602 cases of ILC. Six out of the eight articles reviewed provided information on the bilateral occurrence of ILC based on histopathology. A weighted average calculation yielded a bilaterality percentage of 4.95% (24 out of 485 cases). Four articles reported the number of bilateral cases identified through MRI, resulting in a weighted average of 10.2% (26 out of 255 cases). It is worth noting that 20.4% (100 out of 491) of the performed MRIs were found to be either useless or even harmful. Furthermore, MRI led to a change in the treatment plan in 27.7% (136 out of 491) of cases. Overall, it can be concluded that there is limited available data regarding the bilateral occurrence of ILC. The numbers found in the literature are also inconsistent and tend to vary. The literature review revealed a decrease in the percentage of bilaterality compared to historical beliefs. Based on this study, it can be concluded that a high number of MRI scans were found to be either useless or harmful. As a result of this conclusion and a higher sensitivity of other screening modalities, MRI may no longer be indicated as part of the standard workup for ILC. However, further research is necessary to validate these findings.

Retrospective cohort study on the bilateral occurrence of invasive lobular breast cancer.

OBJECTIVE: Invasive lobular carcinoma (ILC) is the second most common histological subtype of invasive breast cancer, following the no special type (NST) invasive carcinoma. It has historically been assumed that ILC occurs bilaterally in 20-29 % of cases, which has influenced the inclusion of MRI in the standard workup of ILC according to European guidelines. However, challenging this long-held belief regarding the bilateral occurrence of ILC opens up the possibility of revising the guidelines and using MRI only for more specific indications. This study aims to evaluate whether the previously reported high percentage of bilaterality still holds true and to question the added value of MRI in the standard workup of ILC. STUDY DESIGN: A retrospective cohort study was conducted following approval from the institutional review board (EC 21/18/249) at Antwerp University Hospital (UZA). The cohort comprised female patients of all ages who had been diagnosed with either ILC or NST invasive carcinoma and had sought consultation at the UZA breast clinic. A comprehensive database was established to collect information on patient characteristics, imaging, and pathology. RESULTS: A total of 271 patients with ILC were included in the study, with incidence dates ranging from 01/01/2007 to 01/01/2023. Among these patients, a synchronous bilateral ILC lesion was observed in 1.85 % (5/271) of cases. This proportion is significantly lower than the reported percentage of patients with a bilateral lesion in the literature population, which stands at 4.95 %. The reference group consisted of 809 patients with NST invasive carcinoma, with incidence dates ranging from 01/01/2017 to 01/01/2023. In the control group, a synchronous bilateral NST lesion was observed in 3.96 % (32/809) of cases. There is no significant difference in the bilaterality rates between the group of ILC patients and the group of NST patients. Furthermore, MRI did not detect any histopathologically confirmed contralateral ILC lesion that had not already been detected by mammography or ultrasound. CONCLUSIONS: The study results indicate a lower occurrence of bilateral ILC than previously assumed. Additionally, the incidence of synchronous bilateral lesions in ILC patients is not higher compared to patients with NST invasive carcinoma. Performing an MRI does not provide additional value in detecting bilateral carcinomas in ILC. Consequently, it is recommended that the current European guidelines be reassessed, and the indications for undergoing an MRI should be adjusted accordingly.

Comparison of Clinical Breast Exam to Breast MRI Surveillance in Patients Following Nipple-Sparing Mastectomy.

BACKGROUND: Nipple sparing mastectomy (NSM) is increasingly being performed for patients with breast cancer. However, optimal postoperative surveillance has not been defined. METHODS: A prospectively maintained database identified patients with in-situ and invasive cancer who underwent NSM between 2007-2021. Clinical data on postoperative breast surveillance and interventions were collected. Patients who had MRI surveillance versus clinical breast exam (CBE) alone were compared with respect to tumor characteristics, recurrence, and survival. RESULTS: A total of 483 NSMs were performed on 399 patients. 255 (63.9%) patients had invasive ductal carcinoma, 31 (7.8%) invasive lobular carcinoma, 92 (23.1%) DCIS, 6 (1.5%) mixed ductal and lobular carcinoma, 9 (2.3%) others, and 6 (1.5%) unknown. Postoperatively, 265 (66.4%) patients were followed with CBE alone and 134 (33.6%) had surveillance MRIs. At a median follow-up of 33 months, 20 patients (5.0%) developed in-breast recurrence, 6 patients had (1.5%) an axillary recurrence, and 28 with (7.0%) distant recurrence. 14 (53.8%) LRR were detected in the CBE group and 12 (46.2%) were detected in the MRI group (P = .16). Overall survival (OS) was 99%, with no difference in OS between patients who had CBE alone versus MRI (P = .46). MRI was associated with higher biopsy rates compared to CBE alone (15.8% vs. 7.8%, P = .01). CONCLUSIONS: Compared to CBE alone, the use of screening MRI following NSM results in higher rate of biopsy and no difference in overall survival.

Differentiation of invasive ductal and lobular carcinoma of the breast using MRI radiomic features: a pilot study.

Background: Breast cancer (BC) is one of the main causes of cancer-related mortality among women. For clinical management to help patients survive longer and spend less time on treatment, early and precise cancer identification and differentiation of breast lesions are crucial. To investigate the accuracy of radiomic features (RF) extracted from dynamic contrast-enhanced Magnetic Resonance Imaging (DCE MRI) for differentiating invasive ductal carcinoma (IDC) from invasive lobular carcinoma (ILC). Methods: This is a retrospective study. The IDC of 30 and ILC of 28 patients from Dukes breast cancer MRI data set of The Cancer Imaging Archive (TCIA), were included. The RF categories such as shape based, Gray level dependence matrix (GLDM), Gray level co-occurrence matrix (GLCM), First order, Gray level run length matrix (GLRLM), Gray level size zone matrix (GLSZM), NGTDM (Neighbouring gray tone difference matrix) were extracted from the DCE-MRI sequence using a 3D slicer. The maximum relevance and minimum redundancy (mRMR) was applied using Google Colab for identifying the top fifteen relevant radiomic features. The Mann-Whitney U test was performed to identify significant RF for differentiating IDC and ILC. Receiver Operating Characteristic (ROC) curve analysis was performed to ascertain the accuracy of RF in distinguishing between IDC and ILC. Results: Ten DCE MRI-based RFs used in our study showed a significant difference (p <0.001) between IDC and ILC. We noticed that DCE RF, such as Gray level run length matrix (GLRLM) gray level variance (sensitivity (SN) 97.21%, specificity (SP) 96.2%, area under curve (AUC) 0.998), Gray level co-occurrence matrix (GLCM) difference average (SN 95.72%, SP 96.34%, AUC 0.983), GLCM interquartile range (SN 95.24%, SP 97.31%, AUC 0.968), had the strongest ability to differentiate IDC and ILC. Conclusions: MRI-based RF derived from DCE sequences can be used in clinical settings to differentiate malignant lesions of the breast, such as IDC and ILC, without requiring intrusive procedures.

Can 18F-FES PET Improve the Evaluation of 18F-FDG PET in Patients With Metastatic Invasive Lobular Carcinoma?

PURPOSE: Invasive lobular carcinoma (ILC) exhibits a low affinity for 18F-FDG. The estrogen receptor (ER) is commonly expressed in ILCs, suggesting a potential benefit of targeting with the ER probe 18F-FES in this patient population. The objective of this study was to evaluate the diagnostic performance of 18F-FES imaging in patients with metastatic ILC and compare it with that of 18F-FDG. METHODS: We conducted a retrospective analysis of 20 ILC patients who underwent concurrent 18F-FES and 18F-FDG PET/CT examinations in our center. 18F-FES and 18F-FDG imaging were analyzed to determine the total count of tracer-avid lesions in nonbone sites and their corresponding organ systems, assess the extent of anatomical regions involved in bone metastases, and measure the SUVmax values for both tracers. RESULTS: Among 20 ILC patients, 65 nonbone lesions were found to be distributed in 13 patients, and 16 patients were diagnosed with bone metastasis, which was distributed in 54 skeletal anatomical regions. The detection rate of 18F-FDG in nonbone lesions was higher than that of 18F-FES (57 vs 37, P < 0.001). 18F-FES demonstrated a superior ability to detect nonbone lesions in 4 patients, whereas 18F-FDG was superior in 5 patients (P > 0.05). Among 9/16 patients with bone metastasis, 18F-FES demonstrated a significant advantage in the detection of bone lesions compared with 18F-FDG (P = 0.05). Furthermore, patients with only 18F-FES-positive lesions (12/12) were administered endocrine regimens, whereas patients lacking 18F-FES uptake (2/3) predominantly received chemotherapy. CONCLUSIONS: 18F-FES is more effective than 18F-FDG in detecting bone metastasis in ILC, but it does not demonstrate a significant advantage in nonbone lesions. Additionally, the results of examination with 18F-FES have the potential to guide patient treatment plans.

The Role of Magnetic Resonance Imaging in the Preoperative Staging and Treatment of Invasive Lobular Carcinoma.

INTRODUCTION: Invasive lobular carcinoma (ILC) is known for its diffuse growth pattern and its associated challenges in diagnosing. Magnetic resonance imaging (MRI) is the most accurate imaging modality and might aid in improving preoperative staging compared to full field digital mammography (FFDM) and ultrasound (US), however current literature is inconsistent. The aim of this paper is to evaluate the accuracy of MRI staging compared to FFDM/US and pathology results. METHODS: In this single-centre retrospective study, all patients diagnosed with ILC between 2014 and 2019 who underwent preoperative MRI were included. Specific parameters studied were: (1) the need for second-look targeted biopsies, (2) detection of new tumors (ie, contralateral or multifocal), (3) changes in cTNM-classification, and (4) impact on final treatment plan. Bland-Altman plots were used to compare the tumor sizes measured on MRI and FFDM/US with actual pathological tumor sizes. RESULTS: Ninety-nine patients were included. After performing preoperative MRI, 9 (9.1%) multifocal tumors were diagnosed after additional biopsies. Contralateral tumors were detected twice (2.0%) and cN classification was upgraded in 7 cases (7.1%). Surgical treatment or neoadjuvant treatment plans were changed in 16 patients (16.1%). Compared to histopathological results, FFDM/US underestimated tumor size with a mean of 0.4 cm (Limit of agreement (LoA): -2.8 cm to 2.0 cm) whereas MRI overestimated tumor size with a mean of 0.6 cm (LoA: -1.9 cm to 3.0 cm). CONCLUSIONS: In our study, mean differences in tumor size measurements using FFDM/US and MRI were comparable, with similar random errors. MRI correctly diagnosed multifocal and contralateral tumors more often and provided a better cN staging.

The role of contrast-enhanced mammography in the preoperative evaluation of invasive lobular carcinoma of the breast.

AIM: To assess the performance of contrast-enhanced mammography (CEM) in the preoperative staging of invasive lobular carcinoma (ILC) of the breast. MATERIALS AND METHODS: The present study was a multicentre, multivendor, multinational retrospective study of women with a histological diagnosis of ILC who had undergone CEM from December 2013 to December 2021. Index lesion size and multifocality were recorded for two-dimensional (2D) mammography, CEM, and when available magnetic resonance imaging (MRI). Comparison with histological data was undertaken for women treated by primary surgical excision. Pearson correlation coefficients and Bland-Altman's analysis of agreement were used to assess differences with a significance level of 0.05. RESULTS: One hundred and fifteen ILC lesions were included, 46 (40%) presented symptomatically and 69 were screening detected. CEM demonstrated superior sensitivity when compared to standard mammography. The correlation between the histological size measured on the surgical excision specimen size was greater than with standard mammography (r=0.626 and 0.295 respectively, p=0.001), with 19% of lobular carcinomas not visible without a contrast agent. The sensitivity of CEM for multifocal disease was greater than standard mammography (70% and 20% respectively, p<0.0001). CEM overestimated tumour size by an average of 1.5 times, with the size difference increasing for larger tumour. When MRI was performed (n=22), tumour size was also overestimated by an average of 1.3 times. The degree of size overestimation was similar for both techniques, with the tumour size on CEM being on average 0.5 cm larger than MRI. CONCLUSION: CEM is a useful tool for the local staging of lobular carcinomas and could be an alternative to breast MRI.

Gastric Metastasis from Invasive Lobular Breast Cancer, Resembling Primary Gastric Cancer.

Invasive lobular carcinoma (ILC) is the second most common subtype of invasive breast cancer and sometimes presents with an unusual metastatic pattern. Its gastric metastasis is difficult to differentiate from primary adenocarcinoma. This report presents a case of breast ILC for which the initial presentation was gastric metastasis. A 62-y-old woman presented with gastric outlet obstruction secondary to a gastric mass that had been diagnosed on upper gastrointestinal endoscopy and biopsy. The patient had been referred for 18F-FDG PET/CT for staging. The baseline 18F-FDG PET/CT scan demonstrated extensive axillary nodal and gastric metastases with a breast mass, which raised suspicion of a primary breast carcinoma. Distinguishing primary gastric adenocarcinoma from metastatic breast ILC is essential, considering that the 2 diagnoses lead to divergent treatments. Therefore, this entity needs to be considered in the differential diagnosis in clinical practice.

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

OBJECTIVE: 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. METHOD: 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. RESULTS: Ninety-four MRI biopsies diagnosing LN were included. Median age was 57 years (range 37-78 years). 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. CONCLUSIONS: 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.

Impact of pre-operative MRI on surgical management of screening digital breast tomosynthesis-detected invasive lobular carcinoma.

PURPOSE: The purpose of this study is to determine the impact of pre-operative MRI on surgical management of screening digital breast tomosynthesis (DBT)-detected invasive lobular carcinoma (ILC). METHODS: A retrospective medical record analysis was conducted of women with screening DBT-detected ILC and subsequent surgery from 2017-2021. Clinical, imaging, and pathological features were compared between women who did and did not undergo MRI, and between women with and without additional disease detected on MRI, using the Pearson's chi-squared test and Wilcoxon signed-rank test. Concordance between imaging and surgical pathology sizes was also evaluated. RESULTS: Of 125 women (mean age 67 years, range 44-90) with screening-detected ILC, MRI was obtained in 62 women (49.6%) with a mean age of 63 years (range 45-80). Compared to women without MRI, women who had MRI examinations were younger, more likely to have dense breast tissue, and more likely to undergo mastectomy initially rather than lumpectomy (p < 0.001-0.01). Eighteen biopsies were performed based on MRI findings, of which 55.6% (10/18) were malignant. Conventional imaging more frequently underestimated ILC span at the biopsy site than MRI, using a 25% threshold difference (17.5% [7/40] versus 58.5% [24/41], p < 0.001). MRI detected more extensive disease at the biopsy site in six patients (9.7%, 6/62), additional ipsilateral disease in six patients (9.7%, 6/62), and contralateral disease in one patient (1.6%, 1/62). MRI therefore impacted surgical management in 21.0% (13/62) of patients. CONCLUSION: MRI led to the detection of additional disease, thus impacting surgical management, in one-fifth of patients with ILC.

The term "classic invasive lobular carcinoma" of the breast defines breast malignancies of vastly different nature.

PURPOSE: To describe in detail the special features of a previously unappreciated "classic invasive lobular carcinoma" which is confined to the terminal ductal lobular units (TDLUs) and differs considerably from the extensive classic invasive lobular carcinoma, and to suggest specific terminology. METHOD: All invasive breast cancer cases without associated microcalcifications diagnosed in our Institution with the histopathologic diagnosis of classic invasive lobular carcinoma during the years 1996-2019 (n = 560) formed the basis of this study. The cases were prospectively classified according to their imaging biomarkers (mammographic features) and followed up to Dec 31, 2021, to determine long-term patient outcome. An additional 2600 invasive breast cancer cases (diagnosed other than invasive lobular carcinoma) without associated microcalcifications served as a reference group. Detailed histopathologic analysis used large format (10x8 cm) thin section technique and staining methods including hematoxylin-eosin (H&E), E-cadherin, cytokeratin CK 5/6, a transmembrane glycoprotein (CD44) and anti-actin or anti-smooth muscle myosin heavy chain. RESULTS: The imaging biomarkers differentiated two separate disease subgroups, having the same histopathologic diagnosis, classic invasive lobular carcinoma. One of these has the imaging biomarker of extensive architectural distortion with no central tumour mass, occupies the extralobular mesenchyme and has a long-term survival of 56%. The other subgroup forms stellate or circular non-calcified tumour masses usually smaller than 20 mm, which appear to arise in the intralobular mesenchyme, and has a significantly better long-term survival of 84%. CONCLUSIONS: There is a striking difference between the subgross histopathology and the mammographic appearance (imaging biomarkers) of two breast malignancies having the same histopathologic diagnosis, "classic invasive lobular carcinoma". The large difference in the long-term outcome of these two tumour types is even more striking. Using the same specific term, "classic invasive lobular carcinoma", to describe these two separate entities can adversely affect management decisions.

Management of screening-detected lobular neoplasia in the era of digital breast tomosynthesis: A preliminary study.

PURPOSE: The purpose of this study is to determine upgrade rates of lobular neoplasia detected by screening digital breast tomosynthesis (DBT) and to determine imaging and clinicopathological features that may influence risk of upgrade. METHODS: Medical records were reviewed of consecutive women who presented with screening DBT-detected atypical lobular hyperplasia (ALH) and/or lobular carcinoma in situ (LCIS) from January 1, 2013, to June 30, 2020. Included patients underwent needle biopsy and had surgery or at least two-year imaging follow-up. Imaging and clinicopathological features were compared between upgraded and nonupgraded cases of lobular neoplasia using the Pearson's chi-squared test and the Wilcoxon signed-rank test. RESULTS: During the study period, 107 women (mean age 55 years, range 40-88 years) with 110 cases of ALH and/or LCIS underwent surgery (80.9%, n = 89) or at least two-year imaging follow-up (19.1%, n = 21). The overall upgrade rate to cancer was 5.5% (6/110), and the upgrade rate to invasive cancer was 3.6% (4/110). The upgrade rate of ALH to cancer was 4.1% (3/74), whereas the upgrade rate of LCIS to cancer was 9.4% (3/32) (p = .28). The upgrade rate of cases presenting as calcifications was 4.2% (3/71), whereas the upgrade rates of cases presenting as noncalcified findings was 7.7% (3/39) (p = .44). CONCLUSIONS: The upgrade rate of screening DBT-detected lobular neoplasia is less than 6%. Surveillance rather than surgery can be considered for lobular neoplasia, particularly in patients with ALH and in those with screening-detected calcifications leading to the diagnosis.

A role for breast ultrasound Artificial Intelligence decision support in the evaluation of small invasive lobular carcinomas.

OBJECTIVE: To evaluate the diagnostic performance of an Artificial Intelligence (AI) decision support (DS) system in the ultrasound (US) assessment of invasive lobular carcinoma (ILC) of the breast, a cancer that can demonstrate variable appearance and present insidiously. METHODS: Retrospective review was performed of 75 patients with 83 ILC diagnosed by core biopsy or surgery between November 2017 and November 2019. ILC characteristics (size, shape, echogenicity) were recorded. AI DS output (lesion characteristics, likelihood of malignancy) was compared to radiologist assessment. RESULTS: The AI DS system interpreted 100% of ILCs as suspicious or probably malignant (100% sensitivity, and 0% false negative rate). 99% (82/83) of detected ILCs were initially recommended for biopsy by the interpreting breast radiologist, and 100% (83/83) were recommended for biopsy after one additional ILC was identified on same-day repeat diagnostic ultrasound. For lesions in which the AI DS output was probably malignant, but assigned a BI-RADS 4 assessment by the radiologist, the median lesion size was 1 cm, compared with a median lesion size of 1.4 cm for those given a BI-RADS 5 assessment (p = 0.006). These results suggest that AI may offer more useful DS in smaller sub-centimeter lesions in which shape, margin status, or vascularity is more difficult to discern. Only 20% of patients with ILC were assigned a BI-RADS 5 assessment by the radiologist. CONCLUSION: The AI DS accurately characterized 100% of detected ILC lesions as suspicious or probably malignant. AI DS may be helpful in increasing radiologist confidence when assessing ILC on ultrasound.

[A case of extensive digestive tract metastasis from invasive lobular carcinoma of the breast].

A 59-year-old female patient underwent surgery for invasive lobular carcinoma of the right breast 12 years ago. The final diagnosis was invasive lobular carcinoma (T4N1M0 stage IIIB). She underwent chemotherapy, radiotherapy, and hormonal therapy after surgery. She had abdominal bloating and vomiting 12 years after surgery. Contrast-enhanced computed tomography (CECT) and esophagogastroduodenoscopy showed edematous thickening from the stomach to the duodenum and moderate amounts of ascites. Lymph node metastasis was not observed. Biopsy specimens of the stomach revealed signet ring cell carcinoma. Immunochemical studies (ER, GCDFP-15, MUC1, MUC5AC, and MUC6) confirmed gastroduodenal metastasis of invasive lobular carcinoma. Ascites disappeared after she underwent chemotherapy with paclitaxel and bevacizumab; however, wall thickening had spread from the lower esophagus to the stomach, small intestine, colon, and rectum on the CECT. She died 7 months after the diagnosis of gastroduodenal metastasis. Herein, we report a case of invasive lobular carcinoma of the breast with extensive digestive tract metastasis.

The performance of contrast-enhanced mammography and breast MRI in local preoperative staging of invasive lobular breast cancer.

PURPOSE: Breast MRI is considered the best modality for preoperative staging of invasive lobular carcinoma (ILC). However, contrast-enhanced mammography (CEM) shows comparable diagnostic performance to MRI, but evidence of CEM's accuracy in women diagnosed with ILC is scant. We aimed to retrospectively evaluate CEM and MRI accuracy in preoperative staging of ILC. METHODS: ILC cases diagnosed between 2013 and 2021 were collected. For both modalities, tumour diameter was extracted from the reports. Bland-Altman plots were used to assess discrepancies between size measurements according to imaging and histopathological findings. CEM and MRI's ability to detect multifocal/contralateral cancer was expressed as sensitivity, specificity, and diagnostic odds ratios (DORs). Pairwise comparison of women undergoing both CEM and MRI was not performed. RESULTS: 305 ILC-cases fulfilled preset inclusion criteria. Mean age was 63.7 years. Preoperative staging was performed using MRI or CEM in 266 (87.2%) and 77 (25.2%) cases, respectively. MRI and CEM overestimated tumour size by 1.5 and 2.1 mm, respectively. Sensitivity to detect multifocal disease was higher for MRI than for CEM (86% versus 78%), but specificity was lower for MRI (79% versus 92%). For detection of contralateral breast cancer, sensitivity for MRI was 96% versus 88% for CEM, and specificity was 92% and 99%, respectively. For both indications, DOR was higher for CEM, but differences were non-significant (p = 0.56 and p = 0.78). CONCLUSION: CEM and MRI overestimate ILC size with comparable systematic and random errors. MRI's higher sensitivity for detection of multifocal/contralateral cancers is accompanied by lower specificity, but discriminative ability for both modalities was non-significant.

Pathologic Tumor Size versus Mammography, Sonography, and MRI in Breast Cancer Based on Pathologic Subtypes.

INTRODUCTION: The standard of care for imaging of breast pathology has historically been mammography and sonography. MRI is a modern adjunct in the surgeon's toolkit. We looked to examine the differences in imaging modalities and their ability to predict the size in relation to the pathologic size after excision with focus on pathologic subtypes. METHODS: We analyzed patient records across a 4-year period from 2017 to 2021 who were treated surgically for breast cancer at our facility. We used a retrospective chart review to collect measurements that were recorded of the tumors by the radiologist for available mammography, ultrasound, and MRI which were compared to pathology report measurements of the final specimens. We subdivided the results by pathologic subtypes including invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), and ductal carcinoma in situ (DCIS). RESULTS: 658 total patients met criteria for analysis. Mammography overestimated specimens with DCIS by 1.93 mm (P = .15), US underestimated by .56 (.55), and MRI overestimated by 5.77 mm (P < .01). There was no statistically significant difference in any modalities with IDC. With specimens of ILC, all 3 imaging modalities underestimated tumor size, with only US being significant. DISCUSSION: Mammography and MRI consistently overestimated tumor size with the exception of ILC while US underestimated tumor size on all pathologic subtypes. MRI significantly overestimated tumor size in DCIS by 5.77 mm. Mammography was the most accurate imaging modality for all pathologic subtypes and never had a statistically significant difference from actual tumor size.

Management of Lobular Neoplasia Diagnosed by Core Biopsy.

Lobular neoplasia (LN) involves proliferative changes within the breast lobules. LN is divided into lobular carcinoma in situ (LCIS) and atypical lobular hyperplasia (ALH). LCIS can be further subdivided into three subtypes: classic LCIS, pleomorphic LCIS, and LCIS with necrosis (florid type). Because classic LCIS is now considered as a benign etiology, current guidelines recommend close follow-up with imaging versus surgical excision. The goal of our study was to determine if the diagnosis of classic LN on core needle biopsy (CNB) merits surgical excision. This is a retrospective, observational study conducted at Mount Auburn Hospital, Cambridge, MA, from May 17, 2017, through June 30, 2020. We reviewed the data of breast biopsies conducted at our hospital over this period and included patients who were diagnosed with classic LN (LCIS and/or ALH) and excluded patients having any other atypical lesions on CNB. All known cancer patients were excluded. Of the 2707 CNBs performed during the study period, we identified 68 women who were diagnosed with ALH or LCIS on CNB. CNB was performed for an abnormal mammogram in the majority of patients (60; 88%) while 7(10.3%) had an abnormal breast magnetic resonance imaging study (MRI), and 1 had an abnormal ultrasound (US). A total of 58 patients (85%) underwent excisional biopsy, of which 3 (5.2%) showed malignancy, including 2 cases of DCIS and 1 invasive carcinoma. In addition, there was 1 case (1.7%) with pleomorphic LCIS and 11 cases with ADH (15.5%). The management of LN found on core biopsy is evolving, with some advocating surgical excision and others recommending observation. Our data show a change in diagnosis with excisional biopsy in 13 (22.4%) of patients with 2 cases of DCIS, 1 invasive carcinoma, 1 pleomorphic LCIS, and 9 cases of ADH, diagnosed on excisional biopsy. While ALH and classic LCIS are considered benign, the choice of ongoing surveillance versus excisional biopsy should be made with shared decision making with the patient, with consideration of personal and family history, as well as patient preferences.

High-accuracy prediction of axillary lymph node metastasis in invasive lobular carcinoma using focal cortical thickening on magnetic resonance imaging.

BACKGROUND: Invasive lobular carcinoma (ILC) grows diffusely in a single-cell fashion, sometimes presenting only subtle changes in preoperative imaging; therefore, axillary lymph node (ALN) metastases of ILC are difficult to detect using magnetic resonance imaging (MRI). Preoperative underestimation of nodal burden occurs more frequently in ILC than in invasive ductal carcinoma (IDC), however, the morphological assessment for metastatic ALNs of ILC have not fully been investigated. We hypothesized that the high false-negative rate in ILC is caused by the discrepancy in the MRI findings of ALN metastases between ILC and IDC and aimed to identify the MRI finding with a strong correlation with ALN metastasis of ILC. METHOD: This retrospective analysis included 120 female patients (mean ± standard deviation age, 57.2 ± 11.2 years) who underwent upfront surgery for ILC at a single center between April 2011 and June 2022. Of the 120 patients, 35 (29%) had ALN metastasis. Using logistic regression, we constructed prediction models based on MRI findings: primary tumor size, focal cortical thickening (FCT), cortical thickness, long-axis diameter (LAD), and loss of hilum (LOH). RESULTS: The area under the curves were 0.917 (95% confidence interval [CI] 0.869-0.968), 0.827 (95% CI 0.758-0.896), 0.754 (95% CI 0.671-0.837), and 0.621 (95% CI 0.531-0.711) for the FCT, cortical thickness, LAD, and LOH models, respectively. CONCLUSIONS: FCT may be the most relevant MRI finding for ALN metastasis of ILC, and although its prediction model may lead to less underestimation of the nodal burden, rigorous external validation is required.

Prospective Pilot Study of 18F-Fluoroestradiol PET/CT in Patients With Invasive Lobular Carcinomas.

BACKGROUND. PET/CT with 18F-fluoroestradiol (FES) (FDA-approved in 2020) depicts tissues expressing estrogen receptor (ER). Invasive lobular carcinoma (ILC) is commonly ER positive. OBJECTIVE. The primary aim of this study was to assess the frequency with which sites of histologically proven ILC have abnormal uptake on FES PET/CT. METHODS. This prospective single-center pilot study, conducted from December 2020 to August 2021, enrolled patients with histologically confirmed ILC to undergo FES PET/CT; patients optionally underwent FDG PET/CT. Two nuclear radiologists assessed FES PET/CT and FDG PET/CT studies for abnormal uptake corresponding to known ILC sites at enrollment and for additional sites of abnormal uptake, resolving differences by consensus. The primary endpoint was percentage of known ILC sites showing abnormal FES uptake. The alternative to the null hypothesis was that more than 60% of sites would have abnormal FES uptake, exceeding the percentage of ILC with abnormal FDG uptake described in prior literature. A sample size of 24 biopsied lesions was preselected to provide 81% power for the alternative hypothesis (one-sided α = .10). Findings on FES PET/CT and FDG PET/CT were summarized for additional secondary endpoints. RESULTS. The final analysis included 17 patients (mean age, 59.1 ± 13.2 years) with 25 sites of histologically confirmed ILC at enrollment (22 breast lesions, two axillary lymph nodes, one distant metastasis). FES PET/CT showed abnormal uptake in 22 of 25 (88%) lesions, sufficient to reject the null hypothesis (p = .002). Thirteen patients underwent FDG PET/CT. Four of 23 (17%) sites of histologically confirmed ILC, including additional sites detected and confirmed after enrollment, were identified with FES PET/CT only, and 1 of 23 (4%) was identified only with FDG PET/CT (p = .18). FES PET/CT depicted additional lesions not detected with standard-of-care evaluation in 4 of 17 (24%) patients (two contralateral breast cancers and two metastatic axillary lymph nodes, all with subsequent histologic confirmation). Use of FES PET/CT resulted in changes in clinical stage with respect to standard-of-care evaluation in 3 of 17 (18%) patients. CONCLUSION. The primary endpoint of the trial was met. The frequency of abnormal FES uptake among sites of histologically known ILC was found to be to be significantly greater than 60%. CLINICAL IMPACT. This pilot study shows a potential role of FES PET/CT in evaluation of patients with ILC. TRIAL REGISTRATION. ClinicalTrials.gov NCT04252859.