TRPS1 is a promising marker for all subtypes of breast cancer.

AIMS: Trichorhinophalangeal syndrome-1 (TRPS1) has been proposed as a novel breast marker with equally high expression in breast cancer (BC) subtypes, making it a useful diagnostic tool. Here, its expression was evaluated alongside other commonly used markers [GATA3, GCDFP15, mammaglobin (MGB) and SOX10] in a large cohort of BCs (n = 1852) and their corresponding nodal metastases. Its usefulness as a diagnostic tool and its correlation with clinicopathological features were assessed. METHODS AND RESULTS: TRPS1 was expressed at 75.8% overall in the BC cohort, with at least 58% expression among BC subtypes. It was less sensitive than GATA3 for luminal and HER2-overexpressing (HER2-OE) cancers (luminal A: 82 versus 97%; luminal B: 80 versus 95%; HER2-OE: 62 versus 76%), but it was the most sensitive for TNBC (60 versus ≤ 41%). It showed a stable expression in nodal metastases (primary tumour 76 versus nodal metastasis 78%), unlike a reduced nodal expression for GATA3 (86 versus 77%). TRPS1 outperformed GATA3 in detecting non-luminal cancers when paired with other breast markers. TRPS1 and GCDFP15 was the most sensitive combination in TNBC detection, with a 76% detection rate. For TRPS1-negative and GCDFP15-negative TNBCs, SOX10 was more sensitive than GATA3 (29 versus 24%). CONCLUSIONS: TRPS1 is a highly sensitive marker for all breast cancer subtypes, outperforming GATA3 in non-luminal cancers and displaying the highest sensitivity for TNBC detection when combined with GCDFP15. It is a valuable addition to the breast marker panel for accurate identification of BC.

Neutrophil-lymphocyte ratio reflects tumour-infiltrating lymphocytes and tumour-associated macrophages and independently predicts poor outcome in breast cancers with neoadjuvant chemotherapy.

AIMS: The neutrophil-lymphocyte ratio (NLR) is a systemic reflection of cancer-associated inflammation and a prognostic marker for breast cancer. For the local tumour microenvironment, tumour-infiltrating lymphocytes (TILs) and tumour-associated macrophages (TAMs) are also highly correlated with breast cancer survival. This study aimed to explore the relationship between the circulating and local immune microenvironment, and to further delineate the prognostic role of NLR in breast cancer patients receiving neoadjuvant chemotherapy (NAC). METHODS: A cohort of breast cancer patients receiving NAC with subsequent surgery was retrieved. Clinical data were reviewed. Histological slides and CD8 immunohistochemistry from biopsy (pre-chemotherapy) and excision (postchemotherapy) specimens were assessed for TILs and TAMs. RESULTS: A total of 146 patients were included. There was a significant positive correlation between pre- and postsurgery NLR at a cut-off of 2.6 (median pre-chemotherapy NLR) (P < 0.001). NLR pre-chemotherapy was associated positively with necrosis on biopsy (P = 0.027) and excision (P = 0.021) and TAMs on excision (P = 0.049). NLR 1 year postsurgery was associated with high tumour stage (P = 0.050) and low histological grade (P = 0.008). TIL count was lower in NLR-high cases at almost all time-points by histological assessment and CD8 immunostaining (P < 0.050). In multivariate analysis, postsurgery NLR is an independent predictor for overall survival [OS; hazard ratio (HR) = 9.524, P < 0.001], breast cancer-specific survival (BCSS) (HR = 10.059, P = 0.001) and disease-free survival (DFS; HR = 2.824, P = 0.016). CONCLUSIONS: The association between NLR with tumour necrosis, TAMs and TILs illustrates an interaction between the circulating and local immune microenvironment. Late NLR is a strong indicator of outcome and may be useful for prognostication and disease monitoring.

Predictors of an informative or actionable cytological diagnosis on repeat breast aspiration after an insufficient aspirate: a multicentre retrospective review.

An insufficient/inadequate diagnosis on fine-needle aspiration cytology (FNAC) of the breast is not an uncommon diagnostic dilemma. This study aims to review the rate and clinical features predicting an informative or actionable diagnosis on repeating breast aspiration after an insufficient aspirate. METHODS: Unsatisfactory/insufficient/inadequate or equivalent breast aspirates were retrieved from the involved institutions, and those with a repeat aspiration performed within 365 days were included. Clinical and radiological information were retrieved. Available cytological slides were reviewed. RESULTS: Totally 539 paired aspirates were retrieved, with 61.2% (n=330/539) and 10.9% (n=59/539) cytological diagnosis being informative (not insufficient) and actionable (not insufficient nor benign) on repeat aspiration. Younger age (p=0.005) was associated with an informative diagnosis and prior radiotherapy (p=0.097) and insufficient aspirates performed under free-hand (p=0.097) trended with an actionable diagnosis. Radiological findings of calcification (p=0.026) and hyperechogenicity (p=0.045), a small lesion size on initial (p=0.037) and repeat (p=0.059) radiological assessment and interval size increment (p=0.019) correlated with informative/actionable diagnoses. Cytomorphological parameters, except for a trend with crushing artefact (p=0.063), do not correlate with the cytologic diagnosis of the repeat aspirate. CONCLUSIONS: Repeating breast FNAC on patients after an insufficient diagnosis yields an informative ('sufficient') result in over 60% of cases. Small lesions with calcification, hyperechogenicity and/or interval size increment are more likely to yield diagnostic results on repeat aspiration and indicate select patients suitable for repeat FNAC over more invasive procedures. The lack of associations with cytomorphological parameters cautions against overinterpretation of insufficient breast aspirates.

Spatial Distribution and Densities of CD103+ and FoxP3+ Tumor Infiltrating Lymphocytes by Digital Analysis for Outcome Prediction in Breast Cancer.

BACKGROUND: The evaluation of tumor-infiltrating lymphocytes (TILs) for breast cancer prognosis is now established. However, the clinical value for their spatial distributions of specific immune subsets, namely CD103+ tissue-resident memory T cells FoxP3+ regulatory T ells, have not been thoroughly examined. METHOD: Representative whole sections of breast cancers were subjected to CD103 and FoxP3 double staining. Their density, ratio, and spatial features were analyzed in tumor area and tumor-stromal interface. Their associations with clinicopathological parameters and patient's prognosis were analyzed. RESULTS: CD103 TILs were closer to tumor nests than FoxP3 TILs in the tumor-stromal interface. Their densities were associated with high-grade disease, TNBC, and stromal TILs. High stromal FoxP3 (sFoxP3) TILs and close proximity of sCD103 TILs to tumor were independently associated with better survival at multivariate analysis. Subgroup analysis showed the high FoxP3 TILs density associated better survival was seen in HER2-OE and TNBC subtypes while the proximity of CD103 TILs to tumor nests associated better survival was seen in luminal cancers. CONCLUSION: The prognostic impact of CD103 and FoxP3 TILs in breast cancer depends on their spatial localization. High sFoxP3 TIL density and the lower distance of CD103 TILs from the tumor nests had independent favorable prognostic values.

Cytomorphological Assessment in Aspirates of Ductal Carcinoma in situ: Correlations with Histopathologic Grade, Architectural Pattern, and Invasion.

INTRODUCTION: Fine-needle aspiration biopsy (FNAB) of the breast is an effective and widely adopted diagnostic technique. Histopathologic grading of ductal carcinoma in situ (DCIS) has prognostic significance. In this current study, FNAB of DCIS was reviewed to identify parameters that predict grading, histopathologic architecture, and presence of invasion in DCIS. METHODS: Aspirates from histopathology-proven cases of DCIS were retrieved and reviewed for cytomorphologic parameters including cellularity, composition, epithelial fragment architecture cellular/nuclear features. RESULTS: In total 104 aspirates were reviewed. Cytopathologic cellular features - large nuclear size (p = 0.005), prominent nucleoli (p = 0.011), increased nuclear membrane irregularity (p = 0.043), high variation in nuclear size (p = 0.025), and presence of apoptotic figures in epithelial structures (p < 0.001); and background debris (p = 0.033) correlated with a high-grade diagnosis. Cytoplasmic vacuolation (p = 0.034) was seen exclusively in non-high-grade aspirates. Epithelial fragment architecture did not correlate with grading. A predominance (≥50%) of solid aggregates and papillary fragments on FNAB correlated with histopathologically solid (p = 0.039, p = 0.005) and papillary (p = 0.029, < p = 0.001) patterns. No parameter showed correlation with invasion. CONCLUSION: FNAB is effective in predicting DCIS grading. Epithelial fragment architecture assessment is limited to papillary or solid types, and FNAB cannot predict focal invasion in DCIS.

Comprehensive characterization of HER2-low breast cancers: implications in prognosis and treatment.

BACKGROUND: HER2-low cancers are heterogeneous with different degrees of HER2 expression and hormone receptor (HR) status. Currently, its analysis is mostly focused on the standard clinic-pathologic features or common biomarkers expression, without considering the heterogeneity within the category. A further characterization and understanding of this cancer subgroup will facilitate its management. METHODS: A large cohort of HER2-negative cancers (N = 1464) was included. The HER2-low (N = 412) and HER2-zero cancers (N = 1052) were compared and correlated with a comprehensive panel of clinico-pathologic features and biomarker expression according to different HER2 expressions and HR statuses. The prognostic values of these features in HER2-low cancers were also evaluated. FINDINGS: The characteristics of HER2-low breast cancers, as compared to HER2-zero, varied with the HR status. HER2-low luminal cancers were associated with younger age, larger tumor, high pAKT and high HLA expression. Among TNBCs, opposite trends in age and tumor size were found. Additionally, HER2-low TNBC showed less necrosis, higher pN, lower c-kit and CK14 than HER2-zero cancers. Nonetheless, regardless of HR status, HER2-low status was associated with increased COX2 and AR expression, implicated in the biology of HER2-low cancers. HER2-low cancers showed high expression of HLAs in tumors and PD-L1 in immune cells. In particular, the co-expression of HLAs was found to be associated with better survival in HER2-low cancers. INTERPRETATION: This study revealed further characteristic of HER2-low breast cancers as compared to HER2-zero cancers, provided further insights into its prognostication and therapeutic strategies. FUNDING: Health and Medical Research Fund (08190586), Cheng Yue Pui Charity Foundation and CUHK direct grant.

Anatomical site and size of sentinel lymph node metastasis predicted additional axillary tumour burden and breast cancer survival.

AIMS: Sentinel lymph node (SLN) biopsy is the current standard assessment for tumour burden in axillary lymph node (ALN). However, not all SLN+ patients have ALN metastasis. The prognostic implication of SLN features is not clear. We aimed to evaluate predictive factors for ALN metastasis and the clinical value of SLN features. METHODS AND RESULTS: A total of 228 SLN+ and 228 SLN- (with matched year and grade) cases were included. Clinicopathological features in SLN, ALN and primary tumours, treatment data and survival data were analysed according to ALN status and outcome. Except for larger tumour size and the presence of LVI (both P < 0.001), no significant differences were found in SLN- and SLN+ cases. Only 31.8% of SLN+ cases with ALN dissection had ALN metastasis. The presence of macrometastases (MaM), extranodal extension (ENE), deeper level of tumour invasion in SLN and more SLN+ nodes were associated with ALN metastasis (P ≤ 0.025). Moreover, isolated tumour cells (ITC) and level of tumour invasion in SLN were independent adverse prognostic features for disease-free survival and breast cancer-specific survival, respectively. Interestingly, cases with ITC located in the subcapsular region have better survival than those in cortex (OS: χ2  = 4.046, P = 0.044). CONCLUSIONS: Our study identified features in SLN, i.e. the level of tumour invasion at SLN and tumour size in SLN as useful predictors for both ALN metastasis and breast cancer outcome. The presence of ITC, particularly those with a deeper invasion in SLN, portended a worse prognosis. Proper attention should be taken for their management.

WT1 as a myoepithelial marker: a comparative study of breast, cutaneous, and salivary gland lesions.

WT1 immunostain is expressed in various benign and malignant neoplasms, as well as normal myoepithelial cells. WT1 shows differential expression in non-neoplastic, benign, and malignant neoplastic myoepithelial cells of the salivary gland. In this study, WT1 immunostain and other myoepithelial markers were compared to investigate the value of WT1 as a myoepithelial marker, and to delineate the expression profile of WT1 in nonsalivary gland myoepithelial cells. WT1, p63, and calponin immunostains were performed on normal and lesional tissues from the breast (adenosis, sclerosing adenosis, lactating adenoma, nipple adenoma, tubular adenoma, adenomyoepithelioma, and adenoid cystic carcinoma [ACC]), skin (cutaneous mixed tumor, hidradenoma, spiradenoma, and ACC), and salivary gland (pleomorphic adenoma and ACC). The stained slides were digitized and orientated with H&E images and assessed simultaneously using QuPath. A total of 129, 58, and 56 breast, cutaneous, and salivary gland lesions, respectively, were included. There was poor agreement between WT1-p63 and WT1-calponin (κ < 0.1) in all organs, with absence of WT1 expression in normal salivary gland myoepithelium and most ACCs. There were no significant differences in WT1 expression in myoepithelial cells in normal breast tissue and benign breast neoplasms. Compared to pleomorphic adenomas, cutaneous mixed tumors showed lower WT1 expression (P < .001). WT1 is a less sensitive myoepithelial marker than calponin and p63. However, its unique pattern of expression in salivary gland primary for pleomorphic adenomas/cutaneous mixed tumor can favor a diagnosis of benign salivary gland tumors, particularly in small biopsy specimens.

Idiopathic granulomatous mastitis and cystic neutrophilic granulomatous mastitis: two sides of the same coin or distinct entities?

Idiopathic granulomatous mastitis (IGM) is a benign mimic of breast carcinomas. It is defined histologically by the presence of granulomas and inflammation. The closely related cystic neutrophilic granulomatous mastitis (CNGM) shows lipogranulomas, with a reported association with corynebacteria. A large cohort of IGM was reviewed to compare clinical, microbiological and histological features between non-CNGM IGM and CNGM. Cases of IGM were reviewed for histological parameters including the presence of lipogranulomas and composition of inflammatory cells. Clinical data were obtained through hospital records. The cohort included 79 cases, including 51 non-CNGM IGM and 28 CNGM. Comparing non-CNGM IGM and CNGM, there were no differences in clinical or demographical data, other than a younger age of presentation (36.2 vs 41.5 years, p=0.012) for CNGM. Most IGM resolved within the follow-up period (n=57/64, 89.1%), with similar outcomes regardless of treatment (p>0.05). In CNGM, there were more infiltrates of neutrophils (p=0.001), histiocytes (p=0.047), and multinucleated giant cells (p=0.006), but less lymphocytes (p=0.008). Corynebacteria was cultured in two (25%) cases of CNGM, and one non-CNGM IGM (14.3%). Gram-positive bacilli were identified in two cases of CNGM. 'Early' lipogranulomas were observed closely associated to inflamed ducts in three cases of CNGM. Apart from age, there was no distinct clinical or microbiological feature for CNGM. These findings do not support CNGM as a distinct entity. Rather, CNGM-pattern may represent a continuum of IGM, possibly age-related and attributable to ductal inflammation and cystic changes in the breast parenchyma.

Tubular Adenomas of the Breast Are Cytologically Distinct from Fibroadenomas.

INTRODUCTION: Increasing molecular evidence indicates that tubular adenoma of the breast is distinct from fibroepithelial lesions, leading to its reclassification as an epithelial tumor in the 5th World Health Organization classification of tumors of the breast. However, tubular adenoma remains poorly characterized on fine-needle aspiration cytology (FNAC) and often not distinguished from fibroadenomas. In this study, the largest cohort, to date, of histologically confirmed aspirates of tubular adenomas were reviewed and compared with aspirates of fibroadenomas. Findings from this study further define the cytological features of tubular adenoma and allow differentiation from fibroadenoma. METHODOLOGY: Aspirates of histologically confirmed tubular adenomas were reviewed for features of the background, myoepithelial, epithelial, and stromal components and then compared to a cohort of aspirates of fibroadenomas. RESULTS: Totally, 43 (tubular adenoma) and 94 (fibroadenoma) aspirates were included. Tubular adenomas displayed moderate epithelial cellularity with high cohesiveness, with stromal fragments containing epithelium. Tubules are more common in tubular adenomas (p = 0.009) and "tubular fragments" (tissue fragments containing multiple tubular structures with/without stroma) is a pathognomonic feature of tubular adenoma (p < 0.001). Calcification and fibrocystic changes were variably seen (4.65-13.5%) but without difference to fibroadenomas (p > 0.05). Cytomorphologically malignant features and mitoses were absent in all aspirates of tubular adenoma. Presence of tubules and stromal fragments were independent factors associated with tubular adenomas, whereas a predominance of large epithelial fragments and naked stromal fragments were associated with fibroadenomas. CONCLUSION: Tubular adenomas are not only histologically and molecularly separate from fibroepithelial lesions but also a distinct entity on FNAC.

Update on triple-negative breast cancers - highlighting subtyping update and treatment implication.

Triple-negative breast cancer (TNBC) remains a major challenge in breast cancer management. Continuing research in the past years aimed at understanding the biology of this tumour and developing more effective therapeutic options. It is now clear that TNBC is vastly heterogeneous with diverse histological, molecular, immunological profiles and clinical differences. Current evidence suggested the existence of at least four predominant subtypes based on expression profiling across studies. These subtypes exhibited specific genomic alterations and tumour microenvironment. Subtype-specific therapeutic strategies were identified. Recognising these subtypes allows not only an improved prognostication but also a better treatment decision. Herein, we provide an overview of the recent findings on TNBC heterogeneity at different levels and corresponding subtyping. The characteristic of subtypes and the implication of these subtypings in therapeutic approaches are also discussed.

Analysis of recurrent molecular alterations in phyllodes tumour of breast: insights into prognosis and pathogenesis.

Phyllodes tumour (PT) of breast is a rare biphasic neoplasm. Recent next generation sequencing analyses had revealed novel genetic alterations in PT but lacked a further characterisation of their relationship to different PT features and outcome. Here, using targeted sequencing, we examined a panel of 90 recurrently altered or cancer related genes in 88 PT samples (including 49 benign, 25 borderline and 14 malignant PT). Twenty-three genes showed alterations in at least 8.0% of cases. Alterations were significantly higher with an increasing grade of PT (p=0.033), particularly for copy number alterations. The top ten alterations were TERT promoter (58.0%), MED12 (53.4%), RARA (22.8%), FLNA (19.3%), SETD2 (15.9%), SYNE1 (18.2%), PCLO (15.9%), KMT2D (14.3%), CDKN2A (15.9%) and DNAH11 (14.8%). Alterations in CDKN2A/B, EGFR, TP53, PIK3CA, PTEN and ARID1B (p≤0.039) were associated with a higher grade. Analysing alterations based on common pathways indicated a significant correlation of cell cycle pathway and epigenetic alterations with a higher PT grade (p=0.036 and 0.075 respectively). Interestingly, recurrences were not correlated with tumour grade, but related to the presence of RARA mutation (p=0.011) and the absence of alterations in epigenetic pathway (p=0.031). Analysis of synchronous pair of PT showed more differences in gene mutations with divergent MED12 mutation. By contrast, the recurrent samples showed similar genetic alterations as the primary tumours. In summary, we characterised genetic alterations in PTs of different grades and confirmed the recurrent alterations observed in earlier studies. In addition, current data implicated the roles of cell cycle, epigenetic and RARA changes in PT recurrence and tumourogenesis.

Combining Analysis of Tumor-infiltrating Lymphocytes (TIL) and PD-L1 Refined the Prognostication of Breast Cancer Subtypes.

BACKGROUND: PD-L1 has been used as a biomarker to select patients for treatment of PD-1/PD-L1 inhibitors. MATERIALS AND METHODS: In this study, we assessed the clinicopathological features of breast cancers that are associated with PD-L1 expression, as well as its relationship with other immune components and its prognostic significance. RESULTS: Totally 1752 cases were included in this cohort. PD-L1 expression in tumor-infiltrating immune cells (PD-L1-IC) expression and in tumor cells (PD-L1-TC) expression were identified in 34.2% and 10.1% of cases, respectively, and they showed a positive correlation with higher tumor grade, morphological apocrine features, presence of necrosis, and higher stromal tumor-infiltrating lymphocytes (sTIL). PD-L1-IC and PD-L1-TC expression correlated positively with each other, and both of them were negatively associated with estrogen receptor and progesterone receptor and positively associated with Ki67, HER2, EGFR, p63, and p-cadherin. In survival analysis, PD-L1-IC expression was associated with better disease-free survival (DFS) and breast cancer-specific survival (BCSS) in HER2-overexpressed (HER2-OE) cancers and high-grade luminal B cancers. In triple-negative breast cancers (TNBC) and HER2-OE cancers, compared with sTIL low PD-L1-IC negative cases, sTIL high cases showed significantly better DFS independent of PD-L1-IC status. sTIL low PD-L1-IC positive cases also demonstrated a better DFS in HER2-OE cancers. In high-grade luminal B cancers, sTIL high PD-L1-IC positive cases showed the best BCSS. CONCLUSION: The data suggested that the combining analysis of sTIL and PD-L1-IC expression refined the prognostication of breast cancer subtypes. Cases with high TIL and PD-LI-IC expression appear to be more immune active.

Fine needle aspiration cytology of metastatic carcinomas with papillary architecture: A systemic assessment of clinical, cytological and immunohistochemical parameters.

BACKGROUND: Papillary structures are frequently encountered in metastatic carcinomas from various organs and tumours of different histotypes. This study aims to investigate the predictive value of fine needle aspiration cytology (FNAC), immunohistochemistry (IHC) and the clinical parameters which can be examined in the assessment of the primary sites of metastatic carcinomas with papillary architecture. METHODS: FNAC samples of metastatic carcinomas with papillary architecture were evaluated for overall cellularity, epithelial cohesion, background features, papillary architecture, cytology and IHC. The corresponding clinical information was also reviewed. RESULTS: A total of 130 cases were included. The most common primary sites were thyroid (38.5%), lung (30.8%) and gynecological organs (22.3%); the others were pancreaticobiliary, urothelial, colorectal, and esophageal. Age (P = 0.039), biopsy site (P < 0.001) and laterality (P = 0.006) correlated with primary site. Papillary structures were confirmed on biopsy/excision of most cases (n = 85/87, 97.7%). Thyroid primaries exhibited broad papillary stalks, thin lining epithelium, fewer epithelial polymorphs, and the presence of background giant cells and histiocytes (P = 0.021- < 0.001). Low-grade cytological features, nuclear grooves and inclusions (P < 0.001) were seen in thyroid primaries. High-grade features (P < 0.001-0.49), multinucleated tumour cells, apoptotic bodies and mitoses (P < 0.001-0.49) were more common in lung/gynecological primaries. Multivariate analysis identified nuclear/cytoplasmic ratio, chromatin character, the presence of nuclear grooves and mitosis as independent features (P = 0.001-0.024). TTF1/TGB/PAX8 panel results showed good agreement with the cytological assessment and site of primary. CONCLUSION: Papillary structures and cytological features are reproducible in FNAC assessment of metastases and their corresponding primary sites. Cytological features, IHC and clinical information are invaluable in determining the primary site.

An Evaluation of Clinicopathological Correlation and Outcome of Human Epidermal Growth Factor Receptor 2 Subgroups Reclassified According to the Latest ASCO/CAP Guideline.

BACKGROUND: The latest American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guideline has updated the interpretation of uncommon human epidermal growth factor receptor 2 (HER2) in situ hybridization (ISH) patterns (groups 2-4) with concomitant HER2 immunohistochemistry, leading to changes in the diagnosis of these subgroups. We sought to assess the clinicopathological features and outcomes in these subgroups in detail with our local cohort. PATIENTS AND METHODS: Clinicopathologic features of groups 2 to 4 were compared to the typical amplified group (group 1: HER2/CEP17 ≥ 2, HER2 ≥ 4) and non-amplified group (group 5: HER2/CEP17 < 2, HER2 < 4). RESULTS: Group 2 (HER2/CEP17 ≥ 2, HER2 < 4) cases showed lower Ki67 expression and grade (P ≤ .002) than group 1 but no differences compared with group 5. Group 4 (HER2/CEP17 < 2, HER2 = 4-6) cases were associated with less necrosis, more estrogen receptor positivity, lower grade, more nodal metastases, and more special histotypes (P ≤ .037) than group 1, but higher grade and more nodal metastases (P ≤ .021) than group 5. Except for presenting as a larger tumor and of special histotypes, group 3 (HER2/CEP17 < 2, HER2 ≥ 6) cases showed no other significant differences from group 1, but were of higher grade and Ki67 level than groups 2, 4, and 5. Group 4, similar to group 5, showed worse survival than group 1 (disease-free survival: log-rank = 5.547, P = .019; overall survival: log-rank = 4.678, P = .031). The rate of relapse was similar in group 4 with and without anti-HER2 therapy, albeit with limited cases. CONCLUSION: Our findings indicate more similarities among groups 2, 4, and 5 than between groups 1 and 3, supporting the HER2 categorization in the latest guideline. Additional studies may be warranted to assess the outcomes of these patients with different management approaches.

Tumor Microenvironment in Breast Cancer-Updates on Therapeutic Implications and Pathologic Assessment.

The tumor microenvironment (TME) in breast cancer comprises local factors, cancer cells, immune cells and stromal cells of the local and distant tissues. The interaction between cancer cells and their microenvironment plays important roles in tumor proliferation, propagation and response to therapies. There is increasing research in exploring and manipulating the non-cancerous components of the TME for breast cancer treatment. As the TME is now increasingly recognized as a treatment target, its pathologic assessment has become a critical component of breast cancer management. The latest WHO classification of tumors of the breast listed stromal response pattern/fibrotic focus as a prognostic factor and includes recommendations on the assessment of tumor infiltrating lymphocytes and PD-1/PD-L1 expression, with therapeutic implications. This review dissects the TME of breast cancer, describes pathologic assessment relevant for prognostication and treatment decision, and details therapeutic options that interacts with and/or exploits the TME in breast cancer.

The International Academy of Cytology Yokohama System for Reporting Breast Cytopathology showed improved diagnostic accuracy.

BACKGROUND: The aim of the International Academy of Cytology Yokohama System for Reporting Breast Fine Needle Aspiration Biopsy Cytopathology is to improve cytology practice. This study assessed cytologic diagnoses made with the system and its efficacy when it was applied by pathologists with different levels of experience. METHODS: In all, 1080 cases of breast fine-needle aspiration biopsy (FNAB) over a period of 16 years were reviewed and reclassified with the system. The category distribution and the diagnostic performance were compared with the original diagnoses. The concordance rates for diagnoses from pathologists with different levels of experience were also determined. RESULTS: The distribution of cytologic diagnoses made with the system was as follows: 11.7% were insufficient, 56.6% were benign, 20.1% were atypical, 6.1% were suspicious for malignancy, and 5.6% were malignant. The rates for the insufficient and atypical categories were lower than the original diagnosis rates (13.1% and 23.8%, respectively). Overall, 120 cases (11.1%) were recategorized. Among those recategorized as benign, suspicious, or malignant with follow-up data, 96.7% were correctly reclassified. A significant improvement in diagnostic performance was found with the system (P < .001). Such improvement was also seen in problematic breast lesions, including fibroepithelial lesions, papillary lesions, and low-grade carcinomas. Pathologists with intermediate experience showed a higher concordance with an expert pathologist in the diagnoses than those with short experience (κ, 0.838 vs 0.634). CONCLUSIONS: The system effectively categorized the diagnoses, and the diagnostic performance of FNAB reporting was improved. The structured reporting also enhanced the reproducibility of reporting by pathologists with intermediate experience and, to some extent, those with short experience.

Clinicopathologic and genetic features of metaplastic breast cancer with osseous differentiation: a series of 6 cases.

AIMS: Metaplastic breast cancer (MBC) comprises a heterogeneous group of tumors, of which MBC with osseous differentiation (MBC-OD) is extremely rare that only few cases have been reported. This study aimed to present the clinicopathologic and molecular features of MBC-OD. METHODS: We collected 6 cases of MBC-OD from five different centers and described its clinicopathologic and molecular characteristics based on the next-generation sequencing. Another 11 cases from the literature were also reviewed to better characterize the tumor. RESULTS: The tumor primarily showed an osteosarcoma-like appearance, which composed of high cellularity with spindle cells and osteoblast-like cells producing coarse lace-like neoplastic bone (4/6) or osteoid matrix (6/6). 55 somatic mutations including 39 missenses (70.9%), 9 frameshifts (16.4%), 3 splice sites (5.5%), 3 in-frame InDels (5.5%) and 1 nonsense (1.8%) were identified. TP53 was the most frequently mutated genes (5/6, 83.3%), followed by RB1 (3/6, 50.0%), BCOR (2/6, 33.3%), MED12 (2/6, 33.3%), PIK3CA (2/6, 33.3%), and TET2 (2/6, 33.3%). Genetic alterations suggesting therapies with clinical benefit, including mTOR inhibitors, tyrosine kinase inhibitors (TKI), and poly-ADP ribose polymerase inhibitor (PARPi), were observed in five cases. The median follow-up was 21 months (range, 3-80 months). Local recurrence was observed in two cases and three patients displayed distant metastasis. Two patients died of the disease at 3 months and 7 months, respectively. CONCLUSIONS: Based on this series, MBC-OD is a highly aggressive breast tumor with osteosarcoma-like morphology and a high incidence of recurrent disease showing specific genetic profiles.

SETD2 alterations and histone H3K36 trimethylation in phyllodes tumor of breast.

PURPOSE: SETD2 is one of the key epigenetic regulatory genes involved in histone modifications. Its alterations were potentially oncogenic and commonly found in cancers. Interestingly, SETD2 is one of the most frequent mutated genes found exclusively in phyllodes tumor of the breast (PT). However, little has been done to further characterize SETD2 alterations in PT. METHODS: In this study, we examined the alterations of SETD2 gene and protein expression in a large cohort of PTs. Their correlations with SETD2 downstream target, H3K36me3 expression, and clinicopathologic features in PT were also assessed. RESULTS: SETD2 mutation was found in 15.9% of our cases and was mostly predicted to be damaging mutations. Interestingly, SETD2 mutations were associated with lower H3K36me3 expression, particularly those with damaging mutations (p = .041). Neither SETD2 mutations nor H3K36me3 expression was associated with PT grading and other clinicopathological features. By contrast, the SETD2 protein expression cannot reflect its mutation status and showed a different trend of clinicopathological correlations from H3K36me3. CONCLUSIONS: Our findings may suggest a potential involvement of epigenetic regulation via SETD2 alterations and downstream H3K36me3 on PT development. SETD2 mutations may occur early in the pathogenic process of PTs and its loss per se may not be sufficient for progression to malignancy. Exclusive alterations of SETD2 in PT can be used as markers for the diagnosis of fibroepithelial lesions. The association of H3K36me3 with SETD2 mutations may also indicate the value of evaluation of H3K36me3 expression in the diagnosis of fibroepithelial lesions.

Breast cancer with neuroendocrine differentiation: an update based on the latest WHO classification.

Breast cancers with neuroendocrine (NE) differentiation are very heterogeneous, comprising broadly cancers that are morphologically similar to NE tumors (NET) of other anatomic sites, infiltrating breast carcinomas, no special type (IBC-NST) and other special subtypes with NE morphology and/or NE markers expression. Depending on the classification schemes, they are variably included into "NE breast cancers". The latest WHO classification harmonized NE breast cancers with NE neoplasms (NEN) of other organ systems, defined NEN into well-differentiated NET (low Nottingham grade) and poorly-differentiated NE carcinoma (NEC) (high Nottingham grade). Other IBC with NE differentiation are diagnosed based on solely the non-NEN component. Due to the changes in diagnostic criteria, variable results were obtained in the previous studies on NE breast cancers. Hence, the clinical value of NE differentiation in breast cancers is not well investigated and understood. In this review, the current understanding in the pathogenesis, clinical, prognostic, immunhistochemical, and molecular features of "NE breast cancers" is summarized. Controversial issues in their diagnosis and classification are also discussed.