A Nationwide Study on HER2-low Breast Cancer in South Korea: Its Incidence of 2022 Real World Data and the Importance of Immunohistochemical Staining Protocols.

Purpose: Notable effectiveness of trastuzumab deruxtecan (T-DXd) in patients with HER2-low advanced breast cancer (BC) has focused pathologists' attention. We studied the incidence and clinicopathologic characteristics of HER2-low BC, and the effects of immunohistochemistry (IHC) associated factors on HER2 IHC results. Materials and Methods: The Breast Pathology Study Group of the Korean Society of Pathologists conducted a nationwide study using real-world data on HER2 status generated between January 2022 and December 2022. Information on HER2 IHC protocols at each participating institution was also collected. Results: Total 11,416 patients from twenty-five institutions included in this study. Of these patients, 40.7% (range: 6.0%-76.3%) were classified as HER2-zero, 41.7% (range: 10.5%-69.1%) as HER2-low, and 17.5% (range: 6.7%-34.0%) as HER2-positive. HER2-low tumors were associated with positive ER and PR statuses (p<0.001 and p<0.001, respectively). Antigen retrieval times (≥ 36 min vs. < 36 min) and antibody incubation times (≥ 12 min vs. < 12 min) affected on the frequency of HER2 IHC 1+ BC at institutions using the PATHWAY HER2 (4B5) IHC assay and BenchMark XT or Ultra staining instruments. Furthermore, discordant results between core needle biopsy (CNB) and subsequent resection specimen HER2 statuses were observed in 24.1% (787/3259) of the patients. Conclusion: The overall incidence of HER2-low BC in South Korea concurs with those reported in previously published studies. Significant inter-institutional differences in HER2 IHC protocols were observed, and it may have impact on HER2-low status. Thus, we recommend standardizing HER2 IHC conditions to ensure precise patient selection for targeted therapy.

Uterine rupture due to adenomyosis in an adolescent: A case report and review of literature.

BACKGROUND: Uterine rupture is a fatal medical complication with a high mortality rate. Most cases of uterine rupture occur in late pregnancy or during labor and are mainly related to uterine scarring due to previous surgical procedures. Adenomyosis is a possible risk factor for uterine rupture. However, spontaneous uterine rupture due to severe adenomyosis in a non-gravida-teenaged female has not been reported in the literature to date. CASE SUMMARY: A 16-year-old girl was referred to our hospital for acute abdominal pain and hypovolemic shock with a blood pressure of 90/50 mmHg. Radiologic studies revealed a huge endometrial mass with multiple nodules in the lung, suggesting lung metastasis. The patient underwent an emergency total hysterectomy and wedge resection of the lung nodules. Histologically, the uterus showed diffuse adenomyosis with glandular and stromal dissociation. Lung nodules were endometrioma with massive hemorrhage. Immunohistochemistry demonstrated that the tumor cells were positive for PAX8, ER, and PR expression, leading to a final diagnosis of pulmonary endometriosis and uterine adenomyosis. Following surgery, the patient remains in good condition without recurrence. CONCLUSION: This is the first case of spontaneous uterine rupture due to adenomyosis in a non-gravida adolescent.

Metabolic coupling in phyllodes tumor of the breast and its association with tumor progression.

There are markers of metabolic coupling in breast cancer. Loss of caveolin-1 (Cav-1) and upregulation of monocarboxylate transporters (MCTs), especially MCT1 and MCT4, serve an important role in metabolic coupling necessary for release and uptake of metabolites. However, the occurrence of these phenomena in phyllodes tumors (PTs) of the breast is unclear. A total of 101 PTs (60 benign, 26 borderline and 15 malignant) and nine breast tissue samples with no pathological lesions were analyzed. Immunohistochemical staining for Cav-1, MCT1 and MCT4 was performed using tissue microarray and their expression in both stromal and epithelial components was assessed. Cav-1 expression in PTs demonstrated a significant decrease in the stromal component compared with that in the normal breast tissues (P<0.001). MCT1 expression in both epithelial and stromal components was significantly increased in PTs, compared with that in normal breast tissues (both P<0.001). Stromal MCT1 and MCT4 expression were different depending on tumor grade of PTs, and stromal MCT1 expression significantly increased with increasing tumor grade (P<0.001). Although not statistically significant, stromal Cav-1 expression notably decreased with increases in PT grade. High stromal MCT1 expression was significantly associated with lower disease-free survival rate in comparison with low stromal MCT1 expression (P<0.05). These results suggested that changes in protein expression of Cav-1, MCT1 and MCT4 may be associated with tumorigenesis and progression of PTs of the breast.

Prediction of Residual Axillary Nodal Metastasis Following Neoadjuvant Chemotherapy for Breast Cancer: Radiomics Analysis Based on Chest Computed Tomography.

OBJECTIVE: To evaluate the diagnostic performance of chest computed tomography (CT)-based qualitative and radiomics models for predicting residual axillary nodal metastasis after neoadjuvant chemotherapy (NAC) for patients with clinically node-positive breast cancer. MATERIALS AND METHODS: This retrospective study included 226 women (mean age, 51.4 years) with clinically node-positive breast cancer treated with NAC followed by surgery between January 2015 and July 2021. Patients were randomly divided into the training and test sets (4:1 ratio). The following predictive models were built: a qualitative CT feature model using logistic regression based on qualitative imaging features of axillary nodes from the pooled data obtained using the visual interpretations of three radiologists; three radiomics models using radiomics features from three (intranodal, perinodal, and combined) different regions of interest (ROIs) delineated on pre-NAC CT and post-NAC CT using a gradient-boosting classifier; and fusion models integrating clinicopathologic factors with the qualitative CT feature model (referred to as clinical-qualitative CT feature models) or with the combined ROI radiomics model (referred to as clinical-radiomics models). The area under the curve (AUC) was used to assess and compare the model performance. RESULTS: Clinical N stage, biological subtype, and primary tumor response indicated by imaging were associated with residual nodal metastasis during the multivariable analysis (all P < 0.05). The AUCs of the qualitative CT feature model and radiomics models (intranodal, perinodal, and combined ROI models) according to post-NAC CT were 0.642, 0.812, 0.762, and 0.832, respectively. The AUCs of the clinical-qualitative CT feature model and clinical-radiomics model according to post-NAC CT were 0.740 and 0.866, respectively. CONCLUSION: CT-based predictive models showed good diagnostic performance for predicting residual nodal metastasis after NAC. Quantitative radiomics analysis may provide a higher level of performance than qualitative CT features models. Larger multicenter studies should be conducted to confirm their performance.

Expression of Cav-1, MCT1, and MCT4 in Ductal Carcinoma In Situ of the Breast and Their Associations With Clinicopathologic Features.

Loss of caveolin-1 (Cav-1) and upregulation of monocarboxylate transporters (MCTs, especially MCT1 and MCT4) in respectively tumor-associated stromal cells and malignant epithelial cells of invasive carcinoma have been found to play an important role in the metabolic coupling. However, this phenomenon has only been scarcely described in pure ductal carcinoma in situ (DCIS) of the breast. mRNA and protein expression levels of Cav-1, MCT1, and MCT4 in nine pairs of DCIS tissues and matched normal tissues were examined by quantitative real-time polymerase chain reaction, RNAscope in situ hybridization, and immunohistochemistry. Immunohistochemical staining of Cav-1, MCT1, and MCT4 in 79 DCIS samples was also done using tissue microarray. Cav-1 mRNA expression was significantly lower in DCIS tissues than in their corresponding normal tissues. In contrast, MCT1 and MCT4 mRNA expression levels were higher in DCIS tissues than in corresponding normal tissues. Low stromal Cav-1 expression was significantly associated with high nuclear grade. High epithelial MCT4 expression was associated with larger tumor size and human epidermal growth factor 2 positivity. At a mean follow-up of 10 years, patients with high epithelial MCT1/high epithelial MCT4 expression showed shorter disease-free survival than those with other expressions. No significant association was observed between stromal Cav-1 expression and epithelial MCT 1 or MCT4 expression. Changes in Cav-1, MCT1, and MCT4 are associated with carcinogenesis of DCIS. A high epithelial MCT1/high epithelial MCT4 expression might be associated with a more aggressive phenotype.

Malignant Apocrine Lesions of the Breast: Multimodality Imaging Findings and Biologic Features.

The apocrine morphology of the breast is observed in a broad pathological spectrum, ranging from benign cysts to invasive carcinomas. However, the number of clinical research investigating malignant apocrine lesions is limited. This study retrospectively reviewed the data of patients with malignant apocrine lesions admitted in a tertiary center between January 2004 and December 2021, based on the radiology-pathology correlation and the recent advances in their status to enhance the therapeutic implications of androgen receptor (AR). Among the 37 patients with lesions, 27 (73.0%) had triple-negative subtypes with predominant AR expression. The radiological features of malignant apocrine lesions did not differ from those of typical invasive ductal carcinoma or ductal carcinoma in situ. This study demonstrated that knowledge on the imaging features of malignant apocrine lesions and their histological basis could enhance the adoption of new targeted therapies in patients with this particular type of breast cancer.

Prostate-specific membrane antigen expression predicts recurrence of papillary thyroid carcinoma after total thyroidectomy.

BACKGROUND: Prostate-specific membrane antigen (PSMA) overexpression has been observed in the endothelial neovasculature of several solid malignancies. This study aimed to identify PSMA expression in the primary tumor of classical papillary thyroid carcinoma (PTC) and assess the correlation between the degree of PSMA expression and recurrence. METHODS: We reviewed the electronic medical records of patients who underwent total thyroidectomy and central neck dissection, with or without lateral neck dissection, for classical PTC between 2009 and 2014 at our institution. Recurrence was defined as a structural disease based on histological confirmation on follow-up. Fifty-one patients with the recurrent structural disease were matched, using a propensity score matching method, to patients with no disease evidence during follow-up. Clinicopathological and follow-up data were collected for 102 patients. The monoclonal mouse anti-human PSMA/FOLH1/NAALADase I antibody was used for staining the primary tumor. The score of PSMA expression was classified as negative (< 5% positivity), weak (5-10 % positivity), moderate (11-49% positivity), and strong (more than 50% positivity). Clinicopathological factors were compared between patients with low and high PSMA expression. Moreover, whether the degree of PSMA expression and clinicopathological factors could predict recurrence was investigated. Cox proportional hazard regression models were used to evaluate the risk of recurrence. RESULTS: There was no significant difference in clinicopathological factors between low (negative or weak) and high (moderate or strong) PSMA expression. Gross extrathyroidal extension (ETE), absence of chronic lymphocytic thyroiditis, and high PSMA expression were all associated with lower recurrence-free survival (RFS) rate in a univariate analysis. In multivariate analysis, gross ETE (hazard ratio [HR], 2.279; 95% confidence interval [CI], 1.257-4.132; p = 0.007) and high PSMA expression (HR, 1.895; 95% CI, 1.073-3.348; p = 0.028) were associated with poor RFS. CONCLUSIONS: High PSMA expression in the primary tumor was a significant factor in predicting recurrence in classic PTC. PSMA could be a potential biomarker for personalized management for PTC.

Prediction of the histologic upgrade of ductal carcinoma in situ using a combined radiomics and machine learning approach based on breast dynamic contrast-enhanced magnetic resonance imaging.

Objective: To investigate whether support vector machine (SVM) trained with radiomics features based on breast magnetic resonance imaging (MRI) could predict the upgrade of ductal carcinoma in situ (DCIS) diagnosed by core needle biopsy (CNB) after surgical excision. Materials and methods: This retrospective study included a total of 349 lesions from 346 female patients (mean age, 54 years) diagnosed with DCIS by CNB between January 2011 and December 2017. Based on histological confirmation after surgery, the patients were divided into pure (n = 198, 56.7%) and upgraded DCIS (n = 151, 43.3%). The entire dataset was randomly split to training (80%) and test sets (20%). Radiomics features were extracted from the intratumor region-of-interest, which was semi-automatically drawn by two radiologists, based on the first subtraction images from dynamic contrast-enhanced T1-weighted MRI. A least absolute shrinkage and selection operator (LASSO) was used for feature selection. A 4-fold cross validation was applied to the training set to determine the combination of features used to train SVM for classification between pure and upgraded DCIS. Sensitivity, specificity, accuracy, and area under the receiver-operating characteristic curve (AUC) were calculated to evaluate the model performance using the hold-out test set. Results: The model trained with 9 features (Energy, Skewness, Surface Area to Volume ratio, Gray Level Non Uniformity, Kurtosis, Dependence Variance, Maximum 2D diameter Column, Sphericity, and Large Area Emphasis) demonstrated the highest 4-fold mean validation accuracy and AUC of 0.724 (95% CI, 0.619-0.829) and 0.742 (0.623-0.860), respectively. Sensitivity, specificity, accuracy, and AUC using the test set were 0.733 (0.575-0.892) and 0.7 (0.558-0.842), 0.714 (0.608-0.820) and 0.767 (0.651-0.882), respectively. Conclusion: Our study suggested that the combined radiomics and machine learning approach based on preoperative breast MRI may provide an assisting tool to predict the histologic upgrade of DCIS.

DCLK1 promotes colorectal cancer stemness and aggressiveness via the XRCC5/COX2 axis.

Rationale: Doublecortin-like kinase 1 (DCLK1) is a serine/threonine kinase that selectively marks cancer stem-like cells (CSCs) and promotes malignant progression in colorectal cancer (CRC). However, the exact molecular mechanism by which DCLK1 drives the aggressive phenotype of cancer cells is incompletely determined. Methods: Here, we performed comprehensive genomics and proteomics analyses to identify binding proteins of DCLK1 and discovered X-ray repair cross-complementing 5 (XRCC5). Thus, we explored the biological role and downstream events of the DCLK1/XRCC5 axis in human CRC cells and CRC mouse models. Results: The results of comprehensive bioinformatics analyses suggested that DCLK1-driven CRC aggressiveness is linked to inflammation. Mechanistically, DCLK1 bound and phosphorylated XRCC5, which in turn transcriptionally activated cyclooxygenase-2 expression and enhanced prostaglandin E2 production; these events collectively generated the inflammatory tumor microenvironment and enhanced the aggressive behavior of CRC cells. Consistent with the discovered mechanism, inhibition of DCLK1 kinase activity strongly impaired the tumor seeding and growth capabilities in CRC mouse models. Conclusion: Our study illuminates a novel mechanism that mediates the pro-inflammatory function of CSCs in driving the aggressive phenotype of CRC, broadening the biological function of DCLK1 in CRC.

Dysadherin awakens mechanical forces and promotes colorectal cancer progression.

Rationale: Dysadherin is a tumor-associated, membrane-embedded antigen found in multiple types of cancer cells, and associated with malignant behavior of cancer cells; however, the fundamental molecular mechanism by which dysadherin drives aggressive phenotypes of cancer is not yet fully determined. Methods: To get a mechanistic insight, we explored the physiological relevance of dysadherin on intestinal tumorigenesis using dysadherin knockout mice and investigated its impact on clinicopathological features in patients with advanced colorectal cancer (CRC). Next, to discover the downstream signaling pathways of dysadherin, we applied bioinformatic analysis using gene expression data of CRC patient tumors and dysadherin knockout cancer cells. Additionally, comprehensive proteomic and molecular analyses were performed to identify dysadherin-interacting proteins and their functions. Results: Dysadherin deficiency suppressed intestinal tumorigenesis in both genetic and chemical mouse models. Moreover, increased dysadherin expression in cancer cells accounted for shorter survival in CRC patients. Comprehensive bioinformatics analyses suggested that the effect of dysadherin deletion is linked to a reduction in the extracellular matrix receptor signaling pathway. Mechanistically, the extracellular domain of dysadherin bound fibronectin and enhanced cancer cell adhesion to fibronectin, facilitating the activation of integrin-mediated mechanotransduction and leading to yes-associated protein 1 activation. Dysadherin-fibronectin interaction promoted cancer cell growth, survival, migration, and invasion, effects collectively mediated the protumor activity of dysadherin. Conclusion: Our results highlight a novel function of dysadherin as a driver of mechanotransduction that stimulates CRC progression, providing a potential therapy strategy for CRC.

Chondroid syringoma of the axilla: A potential for misdiagnosis as metastatic carcinoma on fine needle aspiration cytology.

Chondroid syringoma is a rare benign adnexal tumor and tends to occur in the head and neck region. Involvement in the axilla is very unusual, and the differential diagnosis of such presentations includes lymphadenopathy and cyst. Fine needle aspiration cytology (FNAC) is a very useful tool for the diagnosis of chondroid syringoma. The characteristic feature of chondroid syringoma in cytology is the presence of distinct biphasic cell populations of epithelial and myoepithelial cells in the chondromyxoid stroma. If the typical biphasic cellular and chondromyxoid stromal elements are not visible in smears, it may be misdiagnosed in cytology. Here, we describe a case of axillary chondroid syringoma that was initially misdiagnosed as a metastatic carcinoma by FNAC. Although chondroid syringoma rarely occurs in the axilla, it should be included among the differential diagnoses of an axillary mass. Cytopathologists need to discern the unique cytological features of chondroid syringoma and avoid misdiagnosis for prompt management of the patient.

Comparison of the Clinicopathologic Features and T-Cell Infiltration of B7-H3 and B7-H4 Expression in Triple-negative Breast Cancer Subtypes.

Previously we revealed an upregulated expression of B7-H3 and B7-H4 mRNA and protein in breast cancer, including triple-negative breast cancer (TNBC). However, little is known regarding the clinical impact and value of B7-H3 and B7-H4 in TNBC subtypes. Thus, this study evaluated the clinicopathologic effects of B7-H3 and B7-H4 mRNA and protein expression according to the TNBC subtypes. RNAscope in situ hybridization and immunohistochemistry of B7-H3 and B7-H4 was done for 186 TNBC samples using tissue microarray. Immunohistochemistry was also performed for TNBC molecular subtype-surrogate markers, CD3, and CD8. TNBCs were classified into basal-like (BL) (64.5%), luminal androgen receptor (10.8%), and unclassifiable (24.7%) subtypes. Tumor B7-H4 mRNA expression was associated with younger age at the initial diagnosis and with molecular TNBC subtypes. Expression of B7-H3 mRNA and protein in the tumor cells was negatively correlated with CD3+ and CD8+ T-cell infiltration density in the tumor and/or stromal region of TNBCs and their subtypes. High stromal B7-H3 mRNA expression was associated with poor disease-free and overall survival in the TNBCs and with overall survival in the unclassifiable subtype. Stromal B7-H3 mRNA expression was independently associated with overall survival and disease-free survival in the TNBCs and BL subtype, respectively. Our results indicate the importance of the stromal expression of B7-H3 mRNA as a prognostic factor in the TNBCs and BL subtype. The inverse relationship between B7-H3 expression and CD3+ and CD8+ T-lymphocyte infiltration represents a promising target for immunotherapy for the TNBCs, especially the BL subtype.

Primary duodenal dedifferentiated liposarcoma: A case report and literature review.

BACKGROUND: Dedifferentiated liposarcoma (DDLPS) is an extremely rare neoplasm that exhibits various morphologies. The tumor is characterized by immunoreactivity to MDM2 and CDK4 and can be confirmed by detecting MDM2 amplification via fluorescence in situ hybridization (FISH). Herein, we report an unusual case of DDLPS arising from the duodenum. CASE SUMMARY: A 64-year-old man presented with repeated abdominal pain and weight loss. Radiologic studies revealed a mass of the duodenum involving the pancreas. The patient was treated with pylorus-preserving pancreaticoduodenectomy. Histologically, the tumor showed a high-grade sarcoma. Immunohistochemistry demonstrated that the tumor cells were positive for MDM2 and CDK4 expression. MDM2 amplification was detected via FISH, leading to the final diagnosis of DDLPS. Following surgery, the patient was treated in the intensive care unit due to peritonitis, and died 60 d after surgery. CONCLUSION: To the best of the authors' knowledge, this is the first case of primary duodenal DDLPS in Korea and the third case in the English-language literature. Care must be taken not to misdiagnose DDLPS as another high-grade tumor. Liposarcoma should be in the differential diagnosis list.

HER2-Positive Breast Cancer: Association of MRI and Clinicopathologic Features With Tumor-Infiltrating Lymphocytes.

BACKGROUND. Tumor-infiltrating lymphocytes (TILs) are associated with therapeutic outcomes and prognosis in patients with human epidermal growth factor receptor type 2 (HER2)-positive breast cancer. Identification of TIL levels is clinically relevant. OBJECTIVE. The purpose of our study was to explore associations of clinicopathologic and MRI features with TIL levels in patients with HER2-positive breast cancer. METHODS. A total of 212 consecutive women (mean age, 54.0 years) diagnosed with HER2-positive breast cancer between January 2017 and December 2019 were included in this retrospective study. Patients were divided into low-TIL (< 10%) and high-TIL (≥ 10%) groups. Three breast radiologists independently reviewed images; interreader agreement was assessed, and the first reader's findings were used for further analysis. Associations of clinicopathologic and MRI features with TIL levels were evaluated using multivariable logistic regression analysis. Subanalysis of TIL levels by hormone receptor (HR) status was also performed. RESULTS. A total of 115 (54.2%) patients had low TIL levels, and 97 (45.8%) patients had high TIL levels. A high TIL level was associated (all, p < .05) with histologic grade 3 (odds ratio [OR] = 3.98; frequency, 78.4% vs 52.2% in high- vs low-TIL groups, respectively), high tumor cellularity (OR = 4.59; median cellularity, 60% vs 50%), lower frequency of associated ductal carcinoma in situ (OR = 0.16; frequency, 86.6% vs 94.8%), and higher frequency of peritumoral edema on T2-weighted images (OR = 2.83; 71.1% vs 50.4%). In subgroup analysis by HR status, histologic grade 3 (OR = 5.03, p = .002) was a significant independent predictor of high TIL level in the HR-positive/HER2-positive group, whereas high tumor cellularity (OR = 9.06, p = .002), peritumoral edema (OR = 5.23, p = .03), and low ADC (OR = 11.69, p = .047) were independent predictors of high TIL level in the HR-negative/HER2-positive group. Interreader agreement for peritumoral edema was moderate among the three radiologists (к = 0.432-0.539). CONCLUSION. Peritumoral edema on MRI and the histopathologic feature of tumor aggressiveness help predict high TIL levels in patients with HER2-positive breast cancer. CLINICAL IMPACT. Pretreatment MRI features may serve as a useful tool for assessing TIL levels in patients with HER2-positive breast cancer and for helping to classify patients with variable clinical outcomes related to immune activity and to guide selection among neoadjuvant chemotherapy or HER2-targeted therapy or immunotherapy.

Classification of MR-Detected Additional Lesions in Patients With Breast Cancer Using a Combination of Radiomics Analysis and Machine Learning.

OBJECTIVE: This study was conducted in order to investigate the feasibility of using radiomics analysis (RA) with machine learning algorithms based on breast magnetic resonance (MR) images for discriminating malignant from benign MR-detected additional lesions in patients with primary breast cancer. MATERIALS AND METHODS: One hundred seventy-four MR-detected additional lesions (benign, n = 86; malignancy, n = 88) from 158 patients with ipsilateral primary breast cancer from a tertiary medical center were included in this retrospective study. The entire data were randomly split to training (80%) and independent test sets (20%). In addition, 25 patients (benign, n = 21; malignancy, n = 15) from another tertiary medical center were included for the external test. Radiomics features that were extracted from three regions-of-interest (ROIs; intratumor, peritumor, combined) using fat-saturated T1-weighted images obtained by subtracting pre- from postcontrast images (SUB) and T2-weighted image (T2) were utilized to train the support vector machine for the binary classification. A decision tree method was utilized to build a classifier model using clinical imaging interpretation (CII) features assessed by radiologists. Area under the receiver operating characteristic curve (AUROC), accuracy, sensitivity, and specificity were used to compare the diagnostic performance. RESULTS: The RA models trained using radiomics features from the intratumor-ROI showed comparable performance to the CII model (accuracy, AUROC: 73.3%, 69.6% for the SUB RA model; 70.0%, 75.1% for the T2 RA model; 73.3%, 72.0% for the CII model). The diagnostic performance increased when the radiomics and CII features were combined to build a fusion model. The fusion model that combines the CII features and radiomics features from multiparametric MRI data demonstrated the highest performance with an accuracy of 86.7% and an AUROC of 91.1%. The external test showed a similar pattern where the fusion models demonstrated higher levels of performance compared with the RA- or CII-only models. The accuracy and AUROC of the SUB+T2 RA+CII model in the external test were 80.6% and 91.4%, respectively. CONCLUSION: Our study demonstrated the feasibility of using RA with machine learning approach based on multiparametric MRI for quantitatively characterizing MR-detected additional lesions. The fusion model demonstrated an improved diagnostic performance over the models trained with either RA or CII alone.

Axillary metastasis from occult breast cancer and synchronous contralateral breast cancer initially suspected to be cancer with contralateral axillary metastasis: a case report.

BACKGROUND: Initial detection of axillary metastasis without known ipsilateral breast cancer could be a challenging diagnostic problem. Four options could be considered for the primary site of the malignancy: ipsilateral occult breast cancer, contralateral breast cancer, tumors in other distant organs, and primary axillary malignancy itself. Although breast cancer is known as the most common primary cancer of axillary metastasis, both occult breast cancer and breast cancer with contralateral axillary metastasis (CAM) are rare. CASE PRESENTATION: A 63-year-old woman presented with palpable right axillary metastasis, and a tiny contralateral breast cancer was detected by breast magnetic resonance imaging. No lesion was found in the ipsilateral right breast and contralateral left axillary region. Both right axillary metastasis and contralateral breast cancer were positive for estrogen receptor. The diagnostic issue was to determine whether the axillary metastasis was derived from the contralateral breast cancer or not. Right axillary dissection and left breast conserving surgery were performed. The final diagnosis was occult breast cancer that presented with axillary lymph node metastasis and early-stage synchronous contralateral breast cancer, based on clinical evidence and postoperative pathologic results. After surgery, systemic treatment and whole breast irradiation were administered. No recurrence or metastasis was observed 15 months postoperatively. CONCLUSION: For accurate diagnosis of axillary metastasis without detectable ipsilateral breast cancer, multifaceted diagnostic approach considering clinical, radiological, and pathological evidences is required.

Evolution of the Tumor Microenvironment toward Immune-Suppressive Seclusion during Brain Metastasis of Breast Cancer: Implications for Targeted Therapy.

Breast cancer (BC) is the second most common solid malignant tumor that metastasizes to the brain. Despite emerging therapies such as immunotherapy, whether the tumor microenvironment (TME) in breast cancer brain metastasis (BCBM) has potential as a target of new treatments is unclear. Expression profiling of 770 genes in 12 pairs of primary BC and matched brain metastasis (BM) samples was performed using the NanoString nCounter PanCancer IO360TM Panel. Immune cell profiles were validated by immunohistochemistry (IHC) in samples from 50 patients with BCBM. Pathway analysis revealed that immune-related pathways were downregulated. Immune cell profiling showed that CD8+ T cells and M1 macrophages were significantly decreased, and M2 macrophages were significantly increased, in BM compared to primary BC samples (p = 0.001, p = 0.021 and p = 0.007, respectively). CCL19 and CCL21, the top differentially expressed genes, were decreased significantly in BM compared to primary BC (p < 0.001, both). IHC showed that the CD8+ count was significantly lower (p = 0.027), and the CD163+ and CD206+ counts were higher, in BM than primary BC (p < 0.001, both). A low CD8+ T cell count, low CD86+ M1 macrophage count, and high M2/M1 macrophage ratio were related to unfavorable clinical outcomes. BC exhibits an immunosuppressive characteristic after metastasis to the brain. These findings will facilitate establishment of a treatment strategy for BCBM based on the TME of metastatic cancer.

A multicenter study of interobserver variability in pathologic diagnosis of papillary breast lesions on core needle biopsy with WHO classification.

BACKGROUND: Papillary breast lesions (PBLs) comprise diverse entities from benign and atypical lesions to malignant tumors. Although PBLs are characterized by a papillary growth pattern, it is challenging to achieve high diagnostic accuracy and reproducibility. Thus, we investigated the diagnostic reproducibility of PBLs in core needle biopsy (CNB) specimens with World Health Organization (WHO) classification. METHODS: Diagnostic reproducibility was assessed using interobserver variability (kappa value, κ) and agreement rate in the pathologic diagnosis of 60 PBL cases on CNB among 20 breast pathologists affiliated with 20 medical institutions in Korea. This analysis was performed using hematoxylin and eosin (H&E) staining and immunohistochemical (IHC) staining for cytokeratin 5 (CK5) and p63. The pathologic diagnosis of PBLs was based on WHO classification, which was used to establish simple classifications (4-tier, 3-tier, and 2-tier). RESULTS: On WHO classification, H&E staining exhibited 'fair agreement' (κ = 0.21) with a 47.0% agreement rate. Simple classifications presented improvement in interobserver variability and agreement rate. IHC staining increased the kappa value and agreement rate in all the classifications. Despite IHC staining, the encapsulated/solid papillary carcinoma (EPC/SPC) subgroup (κ = 0.16) exhibited lower agreement compared to the non-EPC/SPC subgroup (κ = 0.35) with WHO classification, which was similar to the results of any other classification systems. CONCLUSIONS: Although the use of IHC staining for CK5 and p63 increased the diagnostic agreement of PBLs in CNB specimens, WHO classification exhibited a higher discordance rate compared to any other classifications. Therefore, this result warrants further intensive consensus studies to improve the diagnostic reproducibility of PBLs with WHO classification.

Programmed Death Ligand 1 Immunohistochemistry in Triple-Negative Breast Cancer: Evaluation of Inter-Pathologist Concordance and Inter-Assay Variability.

PURPOSE: The programmed death ligand 1 (PD-L1) SP142 assay with a 1% immune cell (IC) cutoff is approved for the selection of advanced triple-negative breast cancer (TNBC) patients for atezolizumab treatment. We aimed to evaluate the interobserver concordance of PD-L1 scoring and inter-assay variability of various PD-L1 assays in TNBC. METHODS: Thirty patients with primary TNBC were selected, and SP142, SP263, 22C3, and E1L3N assays were performed. PD-L1 staining in ICs and tumor cells (TCs) was scored by 10 pathologists who were blinded to the assay. The interobserver concordance among pathologists and the inter-assay variability of the four PD-L1 assays were analyzed. For SP142, the intraobserver concordance among the six pathologists was analyzed after training. RESULTS: The adjusted means of PD-L1 IC scoring ranged from 6.2% to 12.9% for the four assays; the intraclass correlations showed moderate (0.584-0.649) reader concordance. The PD-L1 IC scoring with a 1% cutoff resulted in identical scoring in 40.0%-66.7% of cases and a poor to moderate agreement (Fleiss κ statistic [FKS] = 0.345-0.534) for the four assays. The SP142 assay had the widest range of positive rate (56.5%-100.0%), lowest number of cases with identical scoring, and lowest FKS at 1% cutoff. Pairwise comparison of adjusted means showed significantly decreased PD-L1 staining in SP142 compared with the other assays in both ICs and TCs. As for the intraobserver concordance in the SP142 assay, the overall percent agreement was 87.8% with a 1% IC cutoff. After training, the proportion of cases with identical scoring at a 1% IC cutoff increased to 70.0%; the FKS also increased to 0.610. CONCLUSION: The concordance of PD-L1 IC scoring among pathologists was low, at the 1% cutoff for the SP142 assay without training. SP142 showed the lowest PD-L1 expression in both IC and TC.

Squalene epoxidase expression is associated with breast tumor progression and with a poor prognosis in breast cancer.

Differentially expressed genes (DEGs) have been previously identified using massive parallel RNA sequencing in matched normal, breast cancer (BC) and nodal metastatic tissues. Squalene epoxidase (SQLE), one of these DEGs, is a key enzyme in cholesterol synthesis. The aim of the present study was to investigate the potential involvement of SQLE in the tumorigenic process of BC and to determine its association with the clinical outcome of BC. SQLE mRNA expression was measured using reverse transcription-quantitative PCR in 10 pairs of ductal carcinoma in situ (DCIS) and BC tissues and their adjacent normal tissues. Immunohistochemical staining of SQLE on tissue microarray was performed in 26 normal breast, 79 DCIS and 198 BC samples. The role of SQLE as a prognostic biomarker in patients with BC has been verified using BreastMark. SQLE mRNA expression was significantly increased in DCIS and BC tissues compared with that in their adjacent normal tissues. High SQLE expression was detected in 0, 48.1 and 40.4% of normal breast, DCIS and BC tissues, respectively. SQLE expression in DCIS and BC tissues was significantly higher than that in normal breast tissues. High SQLE expression was observed in DCIS with higher nuclear grade, comedo-type necrosis and HER2 positivity. High SQLE expression in BC was associated with larger tumor size, nodal metastases, higher stage, HER2 subtype and distant metastatic relapse. High SQLE expression was associated with poor disease-free and overall survival, and independently predicted poor disease-free survival in patients with BC. Following BreastMark analysis, high SQLE mRNA expression in BC was significantly associated with a poor prognosis in the 'all', lymph node negative, lymph node positive, luminal A subtype and luminal B subtype groups. Therefore, SQLE expression may be upregulated during the tumorigenic process of BC, and high SQLE expression may be a useful biomarker for predicting a poor prognosis in patients with BC.