Identification of Glandular (Acinar)/Tubule Formation in Invasive Carcinoma of the Breast: A Study to Determine Concordance Using the World Health Organization Definition.

CONTEXT.­: The Nottingham Grading System (NGS) developed by Elston and Ellis is used to grade invasive breast cancer (IBC). Glandular (acinar)/tubule formation is a component of NGS. OBJECTIVE.­: To investigate the ability of pathologists to identify individual structures that should be classified as glandular (acinar)/tubule formation. DESIGN.­: A total of 58 hematoxylin-eosin photographic images of IBC with 1 structure circled were classified as tubules (41 cases) or nontubules (17 cases) by Professor Ellis. Images were sent as a PowerPoint (Microsoft) file to breast pathologists, who were provided with the World Health Organization definition of a tubule and asked to determine if a circled structure represented a tubule. RESULTS.­: Among 35 pathologists, the κ statistic for assessing agreement in evaluating the 58 images was 0.324 (95% CI, 0.314-0.335). The median concordance rate between a participating pathologist and Professor Ellis was 94.1% for evaluating 17 nontubule cases and 53.7% for 41 tubule cases. A total of 41% of the tubule cases were classified correctly by less than 50% of pathologists. Structures classified as tubules by Professor Ellis but often not recognized as tubules by pathologists included glands with complex architecture, mucinous carcinoma, and the "inverted tubule" pattern of micropapillary carcinoma. A total of 80% of participants reported that they did not have clarity on what represented a tubule. CONCLUSIONS.­: We identified structures that should be included as tubules but that were not readily identified by pathologists. Greater concordance for identification of tubules might be obtained by providing more detailed images and descriptions of the types of structures included as tubules.

Breast Carcinoma With Tubulopapillary Features Has a Distinct Immunophenotypic and Molecular Signature: A Report of Two Tumors and Literature Review.

Breast carcinoma with tubulopapillary features is a newly described entity associated with poor prognosis with only 14 tumors reported in the literature. We report 2 additional tumors and identify novel immunohistochemical and molecular features of the tumor. The first tumor was from a 72-year-old woman with nonmetastatic breast carcinoma and the second was from a 32-year-old woman with metastatic breast carcinoma who received neoadjuvant therapy. Both tumors had high-grade nuclear features with a distinctive morphology characterized by infiltrating open glands with intratubular papillary and micropapillary projections in >90% of the invasive carcinoma. In addition to the usual predictors of aggressive behavior, both tumors showed a high expression of p16 and SOX10, which has not been previously described. Targeted tumor sequencing revealed pathogenic variants of TP53 in both tumors, in agreement with previous reports. Prior studies have shown a correlation between p16 and SOX10 expression with high-grade features and worse prognosis; typically seen in triple-negative carcinomas as demonstrated in both of our tumors. However, not all reported tumors of breast carcinoma with tubulopapillary features have demonstrated a triple-negative profile as there are a few reports of tumors with estrogen receptor and/or human epidermal growth factor 2 expression. Due to their distinct morphologic and molecular characteristics, breast carcinoma with tubulopapillary features may represent a new breast cancer histologic subtype.

Pathological response in mucinous carcinoma of breast after neoadjuvant therapy - a multi-institutional study.

Although mucinous carcinoma (MC) is considered a favorable histologic subtype of invasive breast cancer (BC), a subset of MC is managed with neoadjuvant therapy (NAT). The clinical and pathologic features of MC following NAT are not well characterized. The aim of this study is to characterize pathologic response in patients with MC treated with NAT, including neoadjuvant endocrine therapy (NET), neoadjuvant chemotherapy (NCT), and Herceptin-targeted NCT (H-NCT). We conducted a retrospective cohort study of 28 patients with MC who received preoperative adjuvant therapy followed by resection from three institutions between 2010 and 2020. Demographic and clinical information were retrieved from the medical records. Pathologic review of the post NAT resection specimens was performed including tumor grading, tumor size, staging, residual tumor cellularity, estrogen receptor (ER) and HER2 status. Nine (32 %) patients with ER+/HER2- MC received NET, 8 (29 %) ER+/HER2- MC were treated with NCT only and 11 (39 %) HER2+ MC received HER2-targeted NCT (H-NCT). The HER2+ MC patients were younger (45 vs. 64 years; p = 0.006). The HER2+ MC were of higher grade (p = 0.03) and more likely to be multifocal (p = 0.008). Only 2 of 28 (7 %) MC (both HER2+) showed complete pathologic response with residual acellular mucin pools. Persistent mass-forming mucin pools were present in 26 (93 %) cases. The residual tumor cellularity was markedly reduced (≤5 %) in H-NCT treated MC (11/11, 100 %), followed by NET group (6/9, 67 %) and NCT only group (4/8, 50 %) (p = 0.011). Similarly, a higher rate of pathologic response (pCR/RCB-I) was observed in H-NCT (7/11, 64 %), followed by NET group (5/9, 56 %), and NCT only group (1/7, 13 %) (p = 0.053). Post-therapy, all HER2+ MC were smaller than 2 cm and ypT size was significantly smaller in H-NCT group (11/11, 100 %) versus combined NET (5/9, 55 %) and NCT only groups (4/8, 50 %) (p = 0.029). We conclude that ER-/HER2+ and ER+/HER2-mucinous carcinomas of the breast show robust pathological response to neoadjuvant HER2 targeted and endocrine therapy, respectively. Our findings suggest that MC may show good response to endocrine therapy.

Prognostic impact of reduced HER2 protein expression in post-neoadjuvant therapy resection specimens: A single institution experience and review of the literature.

BACKGROUND: Retesting for Human epidermal growth factor receptor-2 (HER2) in post-neoadjuvant therapy resection is variable, and data is conflicting regarding the prognostic significance of changes in HER2 expression pre and post therapy. METHODS: We identified 104 patients with localized HER2 IHC 3+ breast cancer who received neoadjuvant trastuzumab(T)/pertuzumab(P) containing chemotherapy at Yale Cancer Center between 2012 and 2022. Patients were divided into 3 cohorts by response and HER2 IHC in the residual disease: Cohort 1 pathologic complete response (pCR), Cohort 2 pre-treatment IHC 3+/post treatment IHC 1+/2+, and Cohort 3 pre-treatment IHC 3+/post-treatment IHC 3+. Kaplan-Meier survival analysis was performed to assess recurrence free survival at 36 months. RESULTS: The overall pCR rate was 62.5% (65/104), while 37.5% (39/104) of patients had residual disease (RD). Among patients with RD, 58.9% (23/39) remained IHC 3+ and 41.1% (16/39) had reduced HER2 expression IHC1+ or 2+. In patients with HER2 IHC 3+ RD, 26% (6/23) developed local recurrence or distant metastasis while none of patients with post NAT HER2 IHC 1+ or 2+ RD had relapse (p = 0.0309). In patients with pCR, 6.15% (4/65) had recurrence. Kaplan-Meier survival analysis revealed superior disease-free survival in patients with reduced HER2 IHC expression compared to those with remained IHC 3+ (log rank p = 0.004). CONCLUSION: We conclude that reduced HER2 expression by IHC following neoadjuvant treatment was associated with lower recurrence rates in HER2 IHC 3+ breast cancer. If confirmed, RD HER2 IHC expression could be used as a prognostic biomarker to stratify patients in adjuvant trials and identify patients who may benefit from more intensive adjuvant therapy and post therapy surveillance.

SARS-CoV-2 Infection in Unvaccinated High-Risk Pregnant Women in the Bronx, NY, USA Is Associated with Decreased Apgar Scores and Placental Villous Infarcts.

Babies born to severe acute respiratory syndrome corona virus-2 (SARS-CoV-2)-infected mothers are at greater risk for perinatal morbidity and more likely to receive a neurodevelopmental diagnosis in the first year of life. However, the effect of maternal infection on placental function and neonatal outcomes varies depending upon the patient population. We set out to test our hypothesis that maternal SARS-CoV-2 infection in our underserved, socioeconomically disadvantaged, mostly unvaccinated, predominantly African American and Latina population in the Bronx, NY would have effects evident at birth. Under IRB approval, 56 SARS-CoV-2-positive patients infected during the "first wave" of the pandemic with alpha and beta strains of the virus, 48 patients infected during the "second wave" of the pandemic with delta and omicron strains and 61 negative third-trimester high-risk patients were randomly selected from Montefiore Medical Center (MMC), Bronx, NY. In addition, two positive cases from Yale New Haven Hospital, CT were included as controls. All 104 placentas delivered by SARS-CoV-2-positive mothers were uninfected by the virus, based on immunohistochemistry, in situ hybridization, and qPCR analysis. However, placental villous infarcts were significantly increased in first-wave cases compared to second-wave cases or negative controls. Significantly lower Apgar scores at 1 min and 5 min were observed in neonates born to infected mothers with severe symptoms. These findings suggest that even without entering the placenta, SARS-CoV-2 can affect various systemic pathways, culminating in altered placental development and function, which may adversely affect the fetus, especially in a high-risk patient population such as ours. These results underline the importance of vaccination among pregnant women, particularly in low-resource areas.

Intratumor spatial heterogeneity in programmed death-ligand 1 (PD-L1) protein expression in early-stage breast cancer.

PURPOSE: Programmed death-ligand 1 (PD-L1) expression is required for benefit from immune checkpoint inhibitors in metastatic triple negative breast cancer (TNBC). In contrast, in the neoadjuvant setting patients benefited regardless of PD-L1 expression. We hypothesized that, in stages II-III breast cancers, low levels of PD-L1 expression may be sufficient to confer sensitivity to therapy and focal expression could be missed by a biopsy. METHODS: In this study, we examined intratumor spatial heterogeneity of PD-L1 protein expression in multiple biopsies from different regions of breast cancers in 57 primary breast tumors (n = 33 TNBC, n = 19 estrogen receptor-positive [ER-positive], n = 5 human epidermal receptor 2-positive [HER2 +]). E1L3N antibody was used to assess PD-L1 status and staining was scored using the combined positivity score (CPS) with PD-L1 positive defined as CPS ≥ 10. RESULTS: Overall, 19% (11/57) of tumors were PD-L1 positive based on positivity in at least 1 biopsy. Among TNBC, PD-L1 positivity was 27% (9/33). The discordance rate, defined as the same tumor yielding PD-L1 positive and negative samples in different regions, was 16% (n = 9) in the whole study population and 23% (n = 7) in TNBC. Cohen's kappa coefficient of agreement was 0.214 for the whole study and 0.239 for TNBC, both of which falling into a non-statistically significant fair agreement range. Among all PD-L1 positive cases, 82% (n = 9/11) had positivity in only one of the tissue assessments. CONCLUSION: These results indicate that the overall 84% concordance is driven by concordant negative results. In PD-L1 positive cancers, within-tumor heterogeneity in PD-L1 expression exists.

The correlation of ESR1 genetic aberrations with estrogen receptor and progesterone receptor status in metastatic and primary estrogen receptor-positive breast carcinomas.

Genetic aberrations in the Estrogen Receptor 1 (ESR1) gene have been identified as an important mechanism of resistance to endocrine therapy in metastatic breast carcinoma. In this study, we aimed to correlate ESR1 genetic aberrations with the ER and PR status in paired metastatic and primary breast carcinomas. Patients with ER-positive breast cancer were divided into two groups: ESR1 genetic aberration (n = 26) and wild-type control (n = 29) based on genetic profiling of their metastatic tumors. Clinicopathological features and ER/PR status were analyzed in paired primary and metastatic tumors. Although there was no significant difference in ER expression between the ESR1 aberration and control groups in primary tumors, ER positivity rate in metastatic tumors was significantly higher in the ESR1 aberration group than in the control group (100% vs. 86%, P < .05). ESR1 aberrated cases were associated with more liver metastases than control tumors (46% vs. 10%, P < .01). The ER percentage and intensity slightly increased from primary to metastatic tumors in the ESR1 aberration group compared to a decrease in both in the wild-type group (percentage increase 2% vs. decrease 19%, P = .0594; intensity increase 0.04 vs. decrease 0.8, p < .05). Patients with ESR1 aberrated metastases were more likely than those with wild-type ESR1 metastases to have the following characteristics: 1) ER percentage ≥90% and intensity >2, as well as PR percentage ≥30% and intensity >1 in metastatic tumors; 2) ER percentage ≥90% and PR percentage ≥70% in primary tumors; and 3) slightly increase in ER percentage and intensity from primary to metastatic tumors. Based on the ER/PR parameters of paired primary and metastatic breast cancer, ESR1 aberration in metastasis may be predicted.

AI-Powered Biomolecular-Specific and Label-Free Multispectral Imaging Rapidly Detects Malignant Neoplasm in Surgically Excised Breast Tissue Specimens.

CONTEXT.­: Repeated surgery is necessary for 20% to 40% of breast conservation surgeries owing to the unavailability of any adjunctive, accurate, and objective tool in the surgeon's hand for real-time margin assessment to achieve the desired balance of oncologic and cosmetic outcomes. OBJECTIVE.­: To assess the feasibility of using a multispectral autofluorescence imaging device for discriminating malignant neoplasm from normal breast tissue in pathology as a critical step in the development of a device for intraoperative use, and to demonstrate the device's utility for use in processing and prioritizing specimens during frozen section and in the pathology grossing room. DESIGN.­: We performed a preliminary assessment of our device, called the TumorMAP system, on 172 fresh tissue blocks from 115 patients obtained from lumpectomy specimens at the time of initial gross examination and compared the device results with gold standard pathology evaluation. RESULTS.­: The preliminary results demonstrate the potential of our device in detecting breast cancer in fresh tissue samples with a sensitivity of 82%, a specificity of 91%, a positive predictive value of 84%, and a negative predictive value of 89%. CONCLUSIONS.­: Our results suggest that the TumorMAP system is suitable for the detection of malignant neoplasm in freshly excised breast specimens and has the potential to evaluate resection margins in real time.

Multi-institutional Assessment of Pathologist Scoring HER2 Immunohistochemistry.

The HercepTest was approved 20+ years ago as the companion diagnostic test for trastuzumab in human epidermal growth factor 2 (HER2) or ERBB2 gene-amplified/overexpressing breast cancers. Subsequent HER2 immunohistochemistry (IHC) assays followed, including the now most common Ventana 4B5 assay. Although this IHC assay has become the clinical standard, its reliability, reproducibility, and accuracy have largely been approved and accepted on the basis of concordance among small numbers of pathologists without validation in a real-world setting. In this study, we evaluated the concordance and interrater reliability of scoring HER2 IHC in 170 breast cancer biopsies by 18 breast cancer-specialized pathologists from 15 institutions. We used the Observers Needed to Evaluate Subjective Tests method to determine the plateau of concordance and the minimum number of pathologists needed to estimate interrater agreement values for large numbers of raters, as seen in the real-world setting. We report substantial discordance within the intermediate categories (<1% agreement for 1+ and 3.6% agreement for 2+) in the 4-category HER2 IHC scoring system. The discordance within the IHC 0 cases is also substantial with an overall percent agreement (OPA) of only 25% and poor interrater reliability metrics (0.49 Fleiss' kappa, 0.55 intraclass correlation coefficient). This discordance can be partially reduced by using a 3-category system (28.8% vs 46.5% OPA for 4-category and 3-category scoring systems, respectively). Observers Needed to Evaluate Subjective Tests plots suggest that the OPA for the task of determining a HER2 IHC score 0 from not 0 plateaus statistically around 59.4% at 10 raters. Conversely, at the task of scoring HER2 IHC as 3+ or not 3+ pathologists' concordance was much higher with an OPA that plateaus at 87.1% with 6 raters. This suggests that legacy HER2 IHC remains valuable for finding the patients in whom the ERBB2 gene is amplified but unacceptably discordant in assigning HER2-low or HER2-negative status for the emerging HER2-low therapies.

Breast implant-associated anaplastic large-cell lymphoma: A series of two case reports diagnosed by cytopathology.

Breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL) is a rare T-cell lymphoma with a good prognosis. It occurs in association with textured breast implants. Its most common presentation is a late-onset peri-implant effusion. We present two cases of BIA-ALCL diagnosed by cytopathological examination of the fluid collection and describe the cytopathologic findings. Both patients were disease free after implant removal. This report highlights the contribution of the cytopathologic analysis to early diagnosis and definite treatment of BIA-ALCL.

AMACR Expression is a Potential Diagnostic Marker in Apocrine Lesions of Breast, and is Associated with High Histologic Grade and Lymph Node Metastases in Some Invasive Apocrine Breast Cancers.

BACKGROUND: Carcinoma with apocrine differentiation (AC) is a subtype of breast carcinoma with apocrine features in >90% of the tumor. Molecular studies demonstrate AC has high expression of androgen receptor (AR) mRNA. Pure AC lack estrogen receptor (ER), progesterone receptor (PR), and express AR, with variable human epidermal growth factor 2 (HER2) status. Currently, in triple negative AC, no targetable therapies or specific diagnostic markers exist. MATERIALS AND METHODS: α-Methylacyl CoA racemase (AMACR) expression was investigated as a marker of apocrine differentiation using a single-plex immunoperoxidase stain, and a novel AMACR/p63 dual stain in a subset of cases, across 1) benign apocrine lesions (apocrine metaplasia, adenosis) 2) apocrine DCIS (ADCIS), 3) AC/ invasive ductal carcinoma (IDC) with apocrine features, 4) non-apocrine triple negative breast cancer (TNBC) and 5) IDC, no special type. A sub-set of cases were evaluated by tissue microarray. RESULTS: AMACR expression was increased in both AC and ADCIS, with minimal expression in benign breast tissue, TNBC and IDC, NST cases. In invasive cases, those with positive AMACR (>5% positivity) were significantly associated with higher histologic grade (P = .006), initial N stage (chi squared 0.044), and lack of ER or PR expression (both P < .001), with no correlation with overall survival. Analysis of TCGA breast cancer datasets revealed AMACR expression was significantly higher in molecularly defined apocrine carcinomas relative to basal and luminal subtypes. Moreover, high AMACR expression predicted worse relapse-free and distant-metastasis free survival, among both ER-/PR-/Her2- and ER-/PR-/Her2+ breast cancer cohorts (log-rank P = .081 and .00011, respectively). CONCLUSION: AMACR represents a promising diagnostic and prognostic marker in apocrine breast lesions. Further study is needed to determine the biologic and clinical significance of this protein in AC.

Increased Expression of LEF1 and ß-Catenin in Invasive Micropapillary Carcinoma of the Breast is Associated With Lymphovascular Invasion and Lymph Node Metastasis.

Invasive micropapillary breast carcinoma (IMPC) is a rare breast cancer subtype characterized by small tumor cell clusters with loss of stromal attachment, an inside-out growth appearance, and lymphotropism. IMPC is associated with high incidence of lymphovascular invasion (LVI) and lymph node metastasis. Activated Wnt signaling has been implicated in the metastasis of other aggressive breast tumors, including triple-negative and basal-like carcinomas. In this study, we tested whether activated Wnt signaling could be detected in IMPC. Upon ligand binding, the central mediator of the Wnt pathway, ß-catenin, accumulates in the cytosol and translocates to the nucleus where it forms a complex with lymphoid enhancer-binding factor 1 (LEF1) to regulate transcription. We performed immunostaining for ß-catenin and LEF1 on a well-annotated cohort of 40 breast tumors and nodal metastases displaying micropapillary histopathology. Strong nuclear accumulation of ß-catenin was not observed, however a dim cytosolic and/or nuclear accumulation of ß-catenin was sometimes seen in IMPC and this expression pattern was significantly associated with nodal metastasis. ß-catenin expression correlated with the upregulation of LEF1 in IMPC. LEF1 expression was detected in 26 of 40 (65%) cases and was specifically enriched at the invasive front of the tumor and in tumor clusters undergoing LVI. Detection of LEF1 expression in the primary tumor was associated with an increased rate of LVI, lymph node metastasis, and disease relapse. LEF1 and ß-catenin expression levels were significantly higher in metastases compared with primary tumors. In summary, this study demonstrates an association between the upregulation of ß-catenin/LEF1 and the metastasis of IMPC.

PD-L1 protein expression in relation to recurrence score values in early-stage ER + breast cancer.

PURPOSE: We assessed associations between PD-L1 protein expression, RS, tumor grade, and stromal tumor-infiltrating lymphocyte (TIL) count in early-stage ER + cancers. METHODS: FFPE tissue blocks of 213 patients with RS in 2012-2017 were identified. PD-L1 immunohistochemistry was performed with SP142 assay, cases with ≥ 1% tumor-infiltrating immune cell positivity in the tumor area were considered PD-L1 + . TIL scores were determined following the international TIL counting guidelines. PD-L1 expression positivity rates were compared across RS (< 11, 11-25, > 25) and TIL categories (< 10%, 10-29%, > 30%), and tumor grade using Wilcoxon and Chi-square tests. Multivariate analysis was performed using logistic regression. RESULTS: PD-L1 and TIL results were available for 201 and 203 patients. Overall, 53% of cases were PD-L1 +. PD-L1 expression was higher among cases with RS > 25, versus RS < 11 (p = 0.00019) and RS 11-25 (p = 0.0017). PD-L1 positivity also correlated with TIL score, tumor grade, and tumor size. Among cancers with TIL > 30%, 92% were PD-L1 + versus 44% PD-L1 + among TIL < 10% (p = 2.8 × 10-6). Grade 3 cancers had higher PD-L1 positivity (79% PD-L1 +) versus grade 2 (49% PD-L1 +) or 1 tumors (48% PD-L1 +) (p = 0.00047). T2 and T3 tumors had more frequent PD-L1 positivity (67% and 83%, respectively) versus T1 cancers (46%) (p = 0.008). In multivariate analysis, only TIL and RS remained as independent predictors of PD-L1 positivity. CONCLUSION: PD-L1 expression is significantly more frequent and higher in larger tumors (T2, T3), grade 3 cancers, and in cancers with RS > 25. PD-L1 expression also correlates with TIL score.

Further Characterization of Clinicopathologic Features of Cystic Neutrophilic Granulomatous Mastitis.

OBJECTIVES: Clinical and demographic features of cystic neutrophilic granulomatous mastitis (CNGM) have not been fully explored due to the rarity of the disease. Herein we studied clinicopathologic characteristics of CNGM in a sizable hospital-based cohort. METHODS: A case-control study was performed to compare clinicopathologic characteristics between patients with CNGM and granulomatous mastitis other than CNGM and between CNGM with and without Corynebacterium identification. RESULTS: Cases of CNGM (n = 31) and non-CNGM (n = 30) were included. Compared with the non-CNGM group, patients with CNGM were statistically significantly younger (median age: 38 vs 43 years), were less likely to be smokers (9% vs 40%), were more likely to have a painful lesion (97% vs 77%) or a larger mass-like lesion (median size: 4.6 vs 1.9 cm), and tended to have a higher Breast Imaging Reporting and Data System score in radiologic studies (score ≥4: 81% vs 53%), positive Corynebacterium identification results (36% vs 0%), and a longer resolving time (12 vs 6 months; all P values for above comparisons <.05). Among CNGM cases, patients with and without Corynebacterium identification shared a similar clinicopathologic profile. CONCLUSIONS: Our study further demonstrated that CNGM is a unique infectious disease with distinct clinicopathologic features.

Detection of SARS-CoV-2 in tissue: the comparative roles of RT-qPCR, in situ RNA hybridization, and immunohistochemistry.

INTRODUCTION: The emergence of SARS-CoV-2, the causative agent the COVID-19 pandemic, has led to a rapidly expanding arsenal of molecular diagnostic assays for the detection of viral material in tissue specimens. AREAS COVERED: We review the value and shortcomings of available tissue-based assays for SARS-CoV-2 detection in formalin-fixed paraffin-embedded (FFPE) tissue, including immunohistochemistry, in situ hybridization, and quantitative reverse transcription PCR (RT-qPCR). The validation, accuracy, and comparative utility of each method is discussed. Subsequently, we identify commercially available antibodies which render the greatest specificity and reproducibility of staining in FFPE specimens. EXPERT OPINION: We offer expert opinion on the efficacy of such techniques and guidance for future implementation, both clinical and experimental.

Evaluation of TRPS1 Expression in Pleural Effusion Cytology Specimens With Metastatic Breast Carcinoma.

OBJECTIVES: Recent studies have shown that trichorhinophalangeal syndrome type 1 (TRPS1) is a sensitive and specific marker that shows positive staining in breast carcinoma. We conducted this study to evaluate the role of TRPS1 immunohistochemistry (IHC) in differentiating breast primary vs tumors from other primary sites in malignant pleural effusion cytology specimens (MPECSs). METHODS: We selected 61 MPECS cases with cell block material available to analyze TRPS1 IHC staining. Of these 61 cases, 38 cases were metastatic carcinoma (MC) from a breast primary. We primarily selected MC cases confirmed as breast origin based on GATA binding protein 3 IHC positivity, except in two of the cases. The remaining 23 MPECS cases were from various primary sites, including urothelial (n = 6), Müllerian (n = 6), lung adenocarcinoma (n = 6), malignant melanoma (MM; n = 3), and squamous cell carcinoma (SqCC; n = 2). RESULTS: TRPS1 expression was observed in 35 (92%) of 38 MCs of breast origin. The staining intensity was variable, with 18 (47%) cases showing strong nuclear expression. In comparison, no TRPS1 expression was seen in any cases of urothelial carcinoma, MM, and SqCC. However, four of six Müllerian MC cases demonstrated TRPS1 expression. CONCLUSIONS: TRPS1 is a new marker that can be used in an IHC panel to investigate breast origin in MPECS.

COVID-19 & differential effects in twins: Insights from Placenta Pathology.

INTRODUCTION: COVID-19 has been associated with several adverse pregnancy outcomes, including perinatal loss. Differential effects of COVID-19 in a twin pregnancy may provide unique insights into virus-placental interactions. We present a case of perinatal loss of a female fetus with survival of the male co-twin in a pregnancy complicated by COVID-19 and premature delivery. METHODS: Viral detection methods recommended by the NICHD task force were used to identify SARS-CoV-2 and its viral receptors in the placentas and fetal tissue (Antoun et al., 2020) [1] RESULTS: Compared with the surviving twin, we found a more severe intervillous necrosis and a relatively low detection of ACE2 membranous expression in the syncytiotrophoblasts of the female twin that succumbed. DISCUSSION: The interactions of SARS-CoV-2 and ACE2 at the maternal fetal interface within the placenta may play a significant role in perinatal loss, and the effects of fetal sex and gestational age at time of infection need to be explored further.

Cytomorphologic features of SMARCA4-deficient non-small cell lung carcinoma and correlation with immunohistochemical and molecular features.

BACKGROUND: SMARCA4/BRG1-deficient tumors and those that have loss of SMARCA/BRG1 have been described as various aggressive carcinomas and sarcomas, including a subset of non-small cell lung carcinoma (NSCLC). Cytomorphologic features of NSCLCs are yet to be described. The objective of this study was to evaluate the cytomorphologic features, immunohistochemical profile, and molecular profile of SMARCA4/BRG1-deficient NSCLC (SMARCA4-dNSCLC). METHODS: The authors retrospectively searched for cases with SMARCA4/BRG1 functional loss alterations, which were identified in molecular studies and further confirmed by immunocytochemistry, and they reviewed the cytomorphologic features. Tumors with BRG1 loss were also stained with an extensive antibody panel. Molecular profiling and clinical information of the identified cases were scrutinized. RESULTS: In total, 12 cytopathology cases from different anatomic sites were included. All cases showed variable expression of cytokeratin irrespective of type. One-half of cases had glandular features, followed by squamoid features, and poorly differentiated features. The most common cytologic features included sheets or papillary architecture, round or oval cell shapes, nuclear enlargement, moderate-to-marked pleomorphism, and coarse chromatin. Two cases with poorly differentiated cytomorphology had a predominance of single cells, scant cytoplasm, and macronucleoli. Variable expression of epithelial markers was noted in all cases. TP53 was the most frequently co-mutated gene in SMARCA4-dNSLCs. CONCLUSIONS: This study demonstrates that SMARCA4-dNSCLCs can have a wide spectrum of cytomorphologic features, ranging from a relatively well differentiated adenocarcinoma to a poorly differentiated/undifferentiated carcinoma, with the majority of cases exhibiting some high-grade features, such as mitosis, apoptosis, necrosis, and marked pleomorphism.

Concordance in Breast Cancer Grading by Artificial Intelligence on Whole Slide Images Compares With a Multi-Institutional Cohort of Breast Pathologists.

CONTEXT.­: Breast carcinoma grade, as determined by the Nottingham Grading System (NGS), is an important criterion for determining prognosis. The NGS is based on 3 parameters: tubule formation (TF), nuclear pleomorphism (NP), and mitotic count (MC). The advent of digital pathology and artificial intelligence (AI) have increased interest in virtual microscopy using digital whole slide imaging (WSI) more broadly. OBJECTIVE.­: To compare concordance in breast carcinoma grading between AI and a multi-institutional group of breast pathologists using digital WSI. DESIGN.­: We have developed an automated NGS framework using deep learning. Six pathologists and AI independently reviewed a digitally scanned slide from 137 invasive carcinomas and assigned a grade based on scoring of the TF, NP, and MC. RESULTS.­: Interobserver agreement for the pathologists and AI for overall grade was moderate (κ = 0.471). Agreement was good (κ = 0.681), moderate (κ = 0.442), and fair (κ = 0.368) for grades 1, 3, and 2, respectively. Observer pair concordance for AI and individual pathologists ranged from fair to good (κ = 0.313-0.606). Perfect agreement was observed in 25 cases (27.4%). Interobserver agreement for the individual components was best for TF (κ = 0.471 each) followed by NP (κ = 0.342) and was worst for MC (κ = 0.233). There were no observed differences in concordance amongst pathologists alone versus pathologists + AI. CONCLUSIONS.­: Ours is the first study comparing concordance in breast carcinoma grading between a multi-institutional group of pathologists using virtual microscopy to a newly developed WSI AI methodology. Using explainable methods, AI demonstrated similar concordance to pathologists alone.

EZH2 Protein Expression in Triple-negative Breast Cancer Treated With Neoadjuvant Chemotherapy: An Exploratory Study of Association With Tumor Response and Prognosis.

INTRODUCTION: Neaodjuvant chemotherapy is used to treat high risk triple-negative breast cancer (TNBC). Residual cancer burden (RCB) is used to predict risk of relapse after neoadjuvant chemotherapy (NAC); however, it cannot predict disease recurrence with certainty. EZH2 is a targetable oncogenic protein overexpressed in TNBC and associated with metastasis and stem cell expansion. We quantified EZH2 protein expression in TNBC before NAC to examine potential utility as a predictive and prognostic biomarker. MATERIALS AND METHODS: We retrospectively identified 63 patients with localized TNBC treated with NAC. We quantified EZH2 nuclear expression in pretherapy biopsies using a score which included intensity and percent of positive cells at each intensity. EZH2 expression was evaluated as a continuous variable and dichotomized at a score of 210. Logistic regression analysis was used to determine association between EZH2 expression and RCB, tumor-infiltrating lymphocytes, clinicopathologic features and disease-free survival. RESULTS: There was no significant association between EZH2 score and posttreatment RCB class evaluated as a continuous variable (P=0.831) or dichotomized at 210 (P=0.546). On multivariable logistic regression, adjusted for covariates including RCB, EZH2 >210 was associated with development of metastasis (odds ratio=14.35, 95% confidence interval: 2.69-76.66; P=0.002). Logistic regression was run with EZH2 scores as a continuous variable and increased EZH2 score was associated with metastasis (odds ratio=1.10, 95% confidence interval: 1.00-1.03; P=0.047). CONCLUSION: In our study of TNBC treated with NAC, high EZH2 expression in pretherapy core biopsies was significantly associated with metastatic recurrence independent of RCB. The potential value of EZH2 as a biomarker to improve stratification of outcome after NAC should be explored further.