TRPS1 expression is sensitive and specific for primary extramammary Paget disease.

AIMS: Extramammary Paget disease (EMPD) is an epithelial neoplasm that can occur at many sites, including the vulva and scrotum. EMPD is characterised by the presence of neoplastic cells, in single cells and clusters, that infiltrate all layers of non-neoplastic squamous epithelium. The differential diagnosis for EMPD includes melanoma in situ and secondary involvement of tumours from other sites, such as urothelial or cervical; pagetoid spread of tumor cells can also been seen at other sites, such as anorectal mucosa. The most frequently utilised biomarkers for confirming the diagnosis of EMPD include CK7 and GATA3; however, these biomarkers lack specificity. The purpose of this study was to evaluate TRPS1, a newly described breast biomarker, in pagetoid neoplasms of the vulva, scrotum and anorectum. METHODS AND RESULTS: Fifteen cases of primary EMPD of the vulva (two with associated invasive carcinoma) and four primary EMPD of the scrotum showed strong nuclear immunoreactivity for TRPS1. In contrast, five cases of vulvar melanoma in situ, one case of urothelial carcinoma with secondary pagetoid spread into the vulva and two anorectal adenocarcinomas with pagetoid spread into anal skin (one with associated invasive carcinoma) were negative for TRPS1. Additionally, weak nuclear TRPS1 staining was observed in non-neoplastic tissues (e.g. keratinocytes), but always with less intensity when compared to tumour cells. CONCLUSIONS: These results demonstrate that TRPS1 is a sensitive and specific biomarker for EMPD, and may be especially useful for excluding secondary involvement of the vulva by urothelial and anorectal carcinomas.

Invasive lobular carcinoma with extracellular mucin (ILCEM): clinicopathologic and molecular characterization of a rare entity.

Invasive lobular carcinoma with extracellular mucin (ILCEM) is a rare histologic subtype of breast cancer. Little is known about the pathologic or genomic signatures that distinguish ILCEM from classic invasive lobular carcinoma (ILC) or mucinous carcinoma. We studied 17 breast cancers with lobular morphology and extracellular mucin. Thirteen tumors with sufficient tissue for DNA extraction were analyzed by a next generation sequencing (NGS) assay that interrogates 447 genes for mutations and copy number variations (CNVs). Median patient age was 66 yrs (range: 31-77 yrs). Sixteen patients presented with masses, 7 of which were >2 cm. Seven patients had lymph node metastases. The cases of ILCEM were moderately (n = 13) or poorly differentiated (n = 4), frequently exhibiting variant morphology that has not been previously described or emphasized, including grade 3 nuclei (n = 11), diffuse signet ring cells (n = 10), solid growth (n = 4), tumor necrosis (n = 3) or apocrine features (n = 2). All tumors showed absent or reduced membranous E-cadherin expression. Concurrent lobular carcinoma in situ (LCIS) was seen in 11/17 cases, 1 of which was a striking example of signet ring cell LCIS with extracellular mucin. Receptor profiles were ER+/HER2- (n = 15) and ER+/HER2+ (n = 2). With a median follow-up of 83.5 months (range: 3-171 months) in 12 patients with available information, 8 patients had recurrences resulting in 4 cancer-related deaths. The most common CNVs were 16q loss (n = 11) and 1q gain (n = 9). CDH1 gene-level alterations were detected in all but one case, including frameshift (n = 7), nonsense (n = 2), and donor splice site (n = 1) mutations and indels (n = 2). Recurrent mutations were also seen in PIK3CA (n = 3), POLQ (n = 3), TP53 (n = 3), ERBB3 (n = 3), ERBB2 (n = 2), and RUNX1 (n = 2). Genes with recurrent amplifications included GATA3 (n = 4), FOXA1 (n = 3), CCND1 (n = 2). Our data highlights ILCEM as a distinct variant of ILC that often presents with higher-grade and variant morphologic features and is associated with an aggressive clinical course. NGS data support an overall lobular-type molecular profile and reveal potentially targetable alterations in a subset of cases with recurrence.

Presence of Non-classic LCIS Is Not a Contraindication to Breast Conservation in Patients with Concomitant Invasive Breast Cancer or DCIS.

BACKGROUND: Non-classic lobular carcinoma in situ (NC-LCIS) represents a spectrum of lesions, histologically distinct from classic LCIS (C-LCIS) and ductal carcinoma in situ (DCIS). Several studies have reported on the safety of breast conservation (BCS) in patients with DCIS or invasive breast cancer and concomitant C-LCIS, yet there are no data addressing this question for patients with concomitant NC-LCIS. We evaluated local recurrence (LR) after BCS in patients with DCIS or invasive cancer and concomitant NC-LCIS. PATIENTS AND METHODS: We searched institutional databases using natural language processing to identify patients with DCIS or invasive breast cancer and concomitant NC-LCIS treated with BCS between 2000 and 2015. Charts were reviewed to collect demographics, disease and treatment details, and recurrence events. All results represent descriptive analyses. RESULTS: We identified 71 patients with DCIS (n = 13) or invasive cancer (n = 58) and concomitant NC-LCIS treated with BCS. Median patient age was 59 years (33-77 years), and median invasive tumor size was 1.2 cm (0.1-6.9 cm); 62% of DCIS and 79% of invasive cancer patients had hormone receptor (HR)-positive disease. Among DCIS patients, seven (54%) received radiation and none hormonal therapy. Among those with invasive cancer, 52 (90%) received radiation, 17 (29%) received chemotherapy and 44 of 55 with HR-positive disease (78%) received hormonal therapy. At median follow-up of 79 months (1-265 months), the LR rate was 8% and 2% among patients with DCIS and invasive cancer, respectively. CONCLUSION: NC-LCIS is rarely present in association with DCIS or invasive cancer, and it does not appear to impact LR outcomes following BCS.

Detection of ERBB2 amplification in uterine serous carcinoma by next-generation sequencing: an approach highly concordant with standard assays.

Uterine serous carcinoma is an aggressive subtype of endometrial cancer that accounts for fewer than 10% of endometrial carcinomas but is responsible for about half of deaths. A subset of cases has HER2 overexpression secondary to ERBB2 gene amplification, and these patients may benefit from anti-HER2 therapies, such as trastuzumab. HER2 protein overexpression is currently assessed by immunohistochemistry (IHC) and ERBB2 gene amplification by fluorescence in situ hybridization (FISH). Targeted next-generation sequencing (NGS) is increasingly used to routinely identify predictive and prognostic molecular abnormalities in endometrial carcinoma. To investigate the ability of a targeted NGS panel to detect ERBB2 amplification, we identified cases of uterine serous carcinoma (n = 93) and compared HER2 expression by IHC and copy number assessed by FISH with copy number status assessed by NGS. ERBB2 copy number status using a combination of IHC and FISH was interpreted using the 2018 ASCO/CAP guidelines for breast carcinoma. ERBB2 amplification by NGS was determined by the relative number of reads mapping to ERBB2 in tumor DNA compared to control nonneoplastic DNA. Cases with copy number ≥6 were considered amplified and copy number <6 were non-amplified. By IHC, 70 specimens were classified as negative (0 or 1+), 19 were classified as equivocal (2+), and 4 were classified as positive (3+). Using combined IHC/FISH, ERBB2 amplification was observed in 8 of 93 cases (9%). NGS identified the same 8 cases with copy number ≥6; all 85 others had copy number <6. In this series, NGS had 100% concordance with combined IHC/FISH in identifying ERBB2 amplification. NGS is highly accurate in detecting ERBB2 amplification in uterine serous carcinoma and provides an alternative to measurement by IHC and FISH.

Clinicopathological and molecular characterisation of 'multiple-classifier' endometrial carcinomas.

Endometrial carcinoma (EC) molecular classification based on four molecular subclasses identified in The Cancer Genome Atlas (TCGA) has gained relevance in recent years due to its prognostic utility and potential to predict benefit from adjuvant treatment. While most ECs can be classified based on a single classifier (POLE exonuclease domain mutations - POLEmut, MMR deficiency - MMRd, p53 abnormal - p53abn), a small but clinically relevant group of tumours harbour more than one molecular classifying feature and are referred to as 'multiple-classifier' ECs. We aimed to describe the clinicopathological and molecular features of multiple-classifier ECs with abnormal p53 (p53abn). Within a cohort of 3518 molecularly profiled ECs, 107 (3%) tumours displayed p53abn in addition to another classifier(s), including 64 with MMRd (MMRd-p53abn), 31 with POLEmut (POLEmut-p53abn), and 12 with all three aberrations (MMRd-POLEmut-p53abn). MMRd-p53abn ECs and POLEmut-p53abn ECs were mostly grade 3 endometrioid ECs, early stage, and frequently showed morphological features characteristic of MMRd or POLEmut ECs. 18/28 (60%) MMRd-p53abn ECs and 7/15 (46.7%) POLEmut-p53abn ECs showed subclonal p53 overexpression, suggesting that TP53 mutation was a secondary event acquired during tumour progression. Hierarchical clustering of TCGA ECs by single nucleotide variant (SNV) type and somatic copy number alterations (SCNAs) revealed that MMRd-p53abn tumours mostly clustered with single-classifier MMRd tumours (20/23) rather than single-classifier p53abn tumours (3/23), while POLEmut-p53abn tumours mostly clustered with single-classifier POLEmut tumours (12/13) and seldom with single-classifier p53abn tumours (1/13) (both p ≤ 0.001, chi-squared test). Finally, the clinical outcome of patients with MMRd-p53abn and POLEmut-p53abn ECs [stage I 5-year recurrence-free survival (RFS) of 92.2% and 94.1%, respectively] was significantly different from single-classifier p53abn EC (stage I RFS 70.8%, p = 0.024 and p = 0.050, respectively). Our results support the classification of MMRd-p53abn EC as MMRd and POLEmut-p53abn EC as POLEmut. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Genomic profiling of pleomorphic and florid lobular carcinoma in situ reveals highly recurrent ERBB2 and ERRB3 alterations.

Pleomorphic LCIS (P-LCIS) and florid LCIS (F-LCIS) are morphologic variants distinguished from classic LCIS by marked nuclear pleomorphism and/or an expansile growth pattern with or without necrosis. Given the rarity of these LCIS variants, little data exist regarding their molecular pathogenesis, natural history, and optimal management. The purpose of this study was to genomically profile LCIS variants to gain further insight into their biology. Nineteen cases of pure LCIS variants (17 P-LCIS, 2 F-LCIS) diagnosed on core needle biopsy at our institution from 2006 to 2017 were included, five of which were upgraded to invasive cancer at excision. Macrodissected lesions were analyzed by a hybrid-capture next generation sequencing assay that surveyed exonic sequences of 447 genes for mutations and copy number variations (CNVs) and 191 regions across 60 genes for structural rearrangements. LCIS variants were all confirmed as E-cadherin negative by immunohistochemistry. Receptor profiles among the 17 P-LCIS cases included HR+/HER2- (nine cases), HR+/HER2+ (three cases), HR-/HER2+ (two cases), and HR-/HER2- (three cases). The two F-LCIS cases were HR+/HER2- and HR+/HER2+. All LCIS variants had genetic alterations consistent with a lobular phenotype including 1q gain (16 cases), 16q loss (18 cases), and CDH1 mutations (18 cases). Highly recurrent ERBB2 alterations were noted including mutations (13 cases) and amplifications (six cases). Other significant alterations included mutations in PIK3CA (six cases), RUNX1 (four cases), ERBB3 (four cases), and CBFB (three cases), as well as amplification of CCND1 (five cases). A TP53 mutation was identified in one case of HR-/HER2+ P-LCIS with signet ring cell features that lacked 1q gain and 16q loss. P-LCIS and F-LCIS contain genetic alterations characteristic of lobular neoplasia; however, these LCIS variants are distinguished from classical LCIS reported in the literature by their highly recurrent ERBB2 alterations.

Prospective multi-institutional evaluation of pathologist assessment of PD-L1 assays for patient selection in triple negative breast cancer.

The US Food and Drug Administration (FDA) approved the PD-L1 immunohistochemical assay, SP142, as a companion test to determine eligibility for atezolizumab therapy in patients with advanced triple negative breast cancer (TNBC) but data in lung cancer studies suggest the assay suffers from poor reproducibility. We sought to evaluate reproducibility and concordance in PD-L1 scoring across multiple pathologists. Full TNBC sections were stained with SP142 and SP263 assays and interpreted for percentage (%) immune cell (IC) staining by 19 pathologists from 14 academic institutions. Proportion of PD-L1 positive cases (defined as ≥1% IC) was determined for each assay as well as concordance across observers. We utilized a new method we call Observers Needed to Evaluate Subjective Tests (ONEST) to determine the minimum number of evaluators needed to estimate concordance between large numbers of readers, as occurs in the real-world setting. PD-L1 was interpreted as positive with the SP142 assay in an average 58% of cases compared with 78% with SP263 (p < 0.0001). IC positive continuous scores ranged from 1 to 95% (mean = 20%) and 1 to 90% (mean = 10%) for SP263 and SP142, respectively. With SP142, 26 cases (38%) showed complete two category (<1% vs. ≥1%) concordance; with SP263, 38 cases (50%) showed complete agreement. The intraclass correlation coefficient (ICC) for two category scoring of SP263 and SP142 was 0.513 and 0.560. ONEST plots showed decreasing overall percent agreement (OPA) as observer number increased, reaching a low plateau of 0.46 at ten observers for SP263 and 0.41 at eight observers for SP142. IC scoring with both assays showed poor reproducibility across multiple pathologists with ONEST analysis suggesting more than half of pathologists will disagree about IC scores. This could lead to many patients either receiving atezolizumab when they are unlikely to benefit, or not receiving atezolizumab when they may benefit.

Variability in diagnostic threshold for comedo necrosis among breast pathologists: implications for patient eligibility for active surveillance trials of ductal carcinoma in situ.

Active surveillance trials for low-risk ductal carcinoma in situ (DCIS) are in progress in the United States and Europe. In some of these trials, the presence of comedo necrosis in the DCIS has been an exclusion criterion for trial entry. However, the minimum amount of necrosis required by pathologists for a diagnosis of comedo necrosis is not well-defined. We surveyed 35 experienced breast pathologists to assess their diagnostic threshold for comedo necrosis. Pink circles representing necrosis ranging in extent from 10 to 80% of the duct diameter were superimposed on eight replicate histologic images of a single duct involved by low nuclear grade, solid pattern DCIS. These images were circulated by e-mail to the participating pathologists who were asked to select the image that represents the minimum amount of necrosis that they require for a diagnosis of comedo necrosis. Among the 35 participants, the minimum extent of the duct diameter required for a diagnosis of comedo necrosis was 10% for 4 pathologists, 20% for 5, 30% for 11, 40% for 7, 50% for 6, 60% for 1 and 70% for 1. There was no single threshold about which more than one-third of the pathologists agreed met the minimal criteria for comedo necrosis. We conclude that even among experienced breast pathologists, the threshold for comedo necrosis is highly variable. Our findings highlight the need for a standardized definition of comedo necrosis as a trial criterion, and more generally where it may be used as a marker of increased risk of recurrence for therapeutic decision making.

Evaluating the Rate of Upgrade to Invasive Breast Cancer and/or Ductal Carcinoma In Situ Following a Core Biopsy Diagnosis of Non-classic Lobular Carcinoma In Situ.

BACKGROUND: A diagnosis of non-classic lobular carcinoma in situ (NC-LCIS) encompasses a variety of lesions with poorly characterized natural history. We evaluated upgrade rates and factors associated with upgrade to malignancy following a core biopsy diagnosis of NC-LCIS, and its natural history. METHODS: Upon Institutional Review Board approval, pathology databases were searched for NC-LCIS core biopsy diagnoses (carcinoma in situ [CIS], CIS with ductal and lobular features [CIS/DLF], pleomorphic LCIS [P-LCIS], variant LCIS [V-LCIS], LCIS with necrosis). Cases with available core and excision pathology were included, while cases with concurrent ipsilateral invasive carcinoma (IC), ductal carcinoma in situ (DCIS), and/or atypical ductal hyperplasia were excluded. RESULTS: Overall, 121 NC-LCIS cases were identified from 1998 to 2017. We excluded 46 cases with concurrent cancer; 75 patients with 76 NC-LCIS core biopsy diagnoses followed by excision formed our study cohort. Median age was 56 years (range 41-83), and all imaging findings were classified as Breast Imaging Reporting and Data System 4; calcifications were the most common biopsy indication (80%). Excision yielded malignancy in 27 (36%) patients (IC 17, 63%; DCIS alone 10, 37%). We were unable to identify radiologic or pathologic features predictive of upgrade. Of 49 pure NC-LCIS cases, 15 (31%) had mastectomy, 9 (18%) had excision and radiation, and 25 (51%) had excision alone. At a median follow-up of 58 months (range 1-224), 1/25 (4%) patients with excision alone developed ipsilateral DCIS 14 months later. CONCLUSIONS: In this series of NC-LCIS, 36% of cases were upgraded, supporting routine excision. We were unable to identify predictors of upgrade. Among 25 patients with pure NC-LCIS, only one patient developed a future ipsilateral cancer. Further study of the natural history of NC-LCIS is warranted.

Morphologic Features Suggestive of Endometriosis in Nondiagnostic Peritoneal Biopsies.

Endometriosis is a common disorder that causes significant morbidity from dysmenorrhea, pelvic pain, and subfertility. Establishment of a definitive diagnosis has important therapeutic implications; however, only approximately 50% of biopsies of laparoscopically suspicious areas provide a diagnosis of endometriosis. Histologic criteria for diagnosis require the presence of endometrial glands or endometrial-type stroma. We hypothesize that other frequently present, but nondiagnostic, histologic features of endometriosis suggest its presence in patients with nondiagnostic peritoneal biopsies. We performed a retrospective clinicopathologic study of morphologic and immunohistochemical features that may improve the histologic diagnosis of endometriosis on laparoscopic peritoneal biopsies. We compared diagnostic (n=88) and nondiagnostic (n=54) peritoneal biopsies from pathologically confirmed endometriosis cases with negative peritoneal biopsies (n=84) from early-stage gynecologic cancer cases. Statistical analysis utilized the Fisher exact test. Multiple morphologic features were significantly increased in nondiagnostic biopsies from patients with endometriosis in comparison with those from negative controls, including foamy macrophages (P=0.0001) and submesothelial stromal clusters (SSCs) (P=0.0008). SSCs ranged from subtle aggregates of spindle cells to nodules of whorled spindle cells with small vessels and extravasated red blood cells resembling stromal endometriosis. Immunohistochemical studies confirmed that ER and CD10-positive SSCs were present in a greater proportion of both nondiagnostic and diagnostic peritoneal biopsies and at a greater number of lesions per biopsy. The overall histologic detection rate of peritoneal biopsies for endometriosis was 62.0%, and inclusion of SSCs with or without foamy macrophages in the diagnostic criteria appreciably increased this rate to between 72.5% and 76.8%. We describe SSCs, which appear to be an early or less developed form of stromal endometriosis, and, when included in the diagnostic criteria, improve the histologic detection rate of endometriosis in peritoneal biopsies.

Massive ovarian edema associated with a broad ligament leiomyoma: a case report and review.

Massive ovarian edema is a rare disorder in which there is marked accumulation of interstitial fluid in the stroma of the ovary. Grossly, the involved ovary is an enlarged solid mass with a smooth tan-white surface, easily confused with a neoplasm. Microscopically, it features diffuse interstitial edema sparing follicles and outer cortex, dilated lymphatic vessels, thick-walled veins, fibromatosis, and luteinized stromal cells. It is believed that massive ovarian edema arises from interference in lymphatic drainage and venous return of the ovary secondary to partial torsion among other etiologies. Herein we provide the first description of unilateral ovarian edema in association with a large leiomyoma in the ipsilateral broad ligament. It is important to recognize the various presentations of this benign entity and to consider it in the differential diagnosis of an adnexal mass in a reproductive age woman.

Copy Number Variation in Inflammatory Breast Cancer.

Identification of a unique genomic biomarker in de novo inflammatory breast cancer (IBC) may provide an insight into the biology of this aggressive disease. The goal of our study was to elucidate biomarkers associated with IBC. We examined breast biopsies collected from Dana-Farber Cancer Institute patients with IBC prior to initiating preoperative systemic treatment (30 samples were examined, of which 14 were eligible). Patients without available biopsies (n = 1), with insufficient tumor epithelial cells (n = 10), or insufficient DNA yield (n = 5) were excluded from the analysis. Molecular subtype and tumor grade were abstracted from a medical records' review. Ten IBC tumors were estrogen-receptor-positive (ER+) and human epidermal growth factor receptor 2 (HER2)-negative (n = 10 out of 14). Sufficient RNA and DNA were simultaneously extracted from 14 biopsy specimens using the Qiagen AllPrep Kit. RNA was amplified using the Sensation kit and profiled using the Affymetrix Human Transcriptome Array 2.0. DNA was profiled for genome-wide copy number variation (CNV) using the Affymetrix OncoScan Array and analyzed using the Nexus Chromosome Analysis Suite. Among the 14 eligible samples, we first confirmed biological concordance and quality control metrics using replicates and gene expression data. Second, we examined CNVs and gene expression change by IBC subtype. We identified significant CNVs in IBC patients after adjusting for multiple comparisons. Next, to assess whether the CNVs were unique to IBC, we compared the IBC CNV data to fresh-frozen non-IBC CNV data from The Cancer Genome Atlas (n = 388). On chromosome 7p11.2, we identified significant CN gain located at position 58,019,983-58,025,423 in 8 ER+ IBC samples compared to 338 non-IBC ER+ samples (region length: 5440 bp gain and 69,039 bp, False Discovery Rate (FDR) p-value = 3.12 × 10-10) and at position 57,950,944-58,025,423 in 3 TN-IBC samples compared to 50 non-IBC TN samples (74,479 base pair, gain, FDR p-value = 4.27 × 10-5; near the EGFR gene). We also observed significant CN loss on chromosome 21, located at position 9,648,315-9,764,385 (p-value = 4.27 × 10-5). Secondarily, differential gene expression in IBC patients with 7p11.2 CN gain compared to SUM149 were explored after FDR correction for multiple testing (p-value = 0.0016), but the results should be interpreted with caution due to the small sample size. Finally, the data presented are hypothesis-generating. Validation of CNVs that contribute to the unique presentation and biological features associated with IBC in larger datasets may lead to the optimization of treatment strategies.

Clinical outcomes of de novo metastatic HER2-positive inflammatory breast cancer.

Inflammatory breast cancer (IBC) is a rare, aggressive form of breast cancer that presents as de novo metastatic disease in 20-30% of cases, with one-third of cases demonstrating HER2-positivity. There has been limited investigation into locoregional therapy utilization following HER2-directed systemic therapy for these patients, and their locoregional progression or recurrence (LRPR) and survival outcomes. Patients with de novo HER2-positive metastatic IBC (mIBC) were identified from an IRB-approved IBC registry at Dana-Farber Cancer Institute. Clinical, pathology, and treatment data were abstracted. Rates of LRPR, progression-free survival (PFS), overall survival (OS), and pathologic complete response (pCR) were determined. Seventy-eight patients diagnosed between 1998 and 2019 were identified. First-line systemic therapy comprised chemotherapy for most patients (97.4%) and HER2-directed therapy for all patients (trastuzumab [47.4%]; trastuzumab+pertuzumab [51.3%]; or trastuzumab emtansine [1.3%]). At a median follow-up of 2.7 years, the median PFS was 1.0 year, and the median OS was 4.6 years. The 1- and 2-year cumulative incidence of LRPR was 20.7% and 29.0%, respectively. Mastectomy was performed after systemic therapy in 41/78 patients (52.6%); 10 had a pCR (24.4%) and all were alive at last follow-up (1.3-8.9 years after surgery). Among 56 patients who were alive and LRPR-free at one year, 10 developed LRPR (surgery group = 1; no-surgery group = 9). In conclusion, patients with de novo HER2-positive mIBC who undergo surgery have favorable outcomes. More than half of patients received systemic and local therapy with good locoregional control and prolonged survival, suggesting a potential role for local therapy.

MRI Changes in Breast Skin Following Preoperative Therapy for Patients with Inflammatory Breast Cancer.

RATIONALE AND OBJECTIVES: Preoperative systemic therapy (PST) followed by mastectomy and radiation improves survival for patients with inflammatory breast cancer (IBC). Residual disease within the skin post-PST adversely impacts surgical outcome and risk of local-regional recurrence (LRR). We aimed to assess magnetic resonance imaging (MRI) breast skin changes post-PST with pathologic response and its impact on surgical resectability. MATERIALS AND METHODS: We retrospectively reviewed 152 baseline and post-PST breast MRIs of 76 patients with IBC. Using the ACR-BIRADS MRI lexicon, we correlated skin thickness, qualitative enhancement, and kinetic analysis with pathologic response in the skin at mastectomy. RESULTS: Baseline MRI showed skin thickening in all 76 patients, 75/76 (99%) showed skin enhancement, 54/75 (72%) had medium/fast initial kinetics, usually with persistent delayed kinetics in 49/54 (91%). Following PST, 66/76 (87%) had residual skin thickening with 64/76 (84%) showing a decrease; 33/76 (43%) had persistent enhancement. The median thickness post-PST was 4.7 mm with residual tumor in the skin, and 3.0 mm without residual tumor (p = 0.008). Regardless of pathologic response, the majority of patients had persistent skin thickening on MRI following PST (100% [14/14] with residual tumor and 84% [52/62] without residual tumor). There was no association between post-PST skin thickness on breast MRI and rate of LRR. CONCLUSION: Patients with IBC have skin thickening and enhancement on baseline breast MRI, with a statistically significant reduction in skin thickness following successful PST. Despite persistent skin changes on MRI, patients achieving a partial or complete parenchymal response to PST may proceed to mastectomy with low LRR rates.

Early on-treatment transcriptional profiling as a tool for improving pathological response prediction in HER2-positive inflammatory breast cancer.

Background: Inflammatory breast cancer (IBC) is a rare and understudied disease, with 40% of cases presenting with human epidermal growth factor receptor 2 (HER2)-positive subtype. The goals of this study were to (i) assess the pathologic complete response (pCR) rate of short-term neoadjuvant dual-HER2-blockade and paclitaxel, (ii) contrast baseline and on-treatment transcriptional profiles of IBC tumor biopsies associated with pCR, and (iii) identify biological pathways that may explain the effect of neoadjuvant therapy on tumor response. Patients and Methods: A single-arm phase II trial of neoadjuvant trastuzumab (H), pertuzumab (P), and paclitaxel for 16 weeks was completed among patients with newly diagnosed HER2-positive IBC. Fresh-frozen tumor biopsies were obtained pretreatment (D1) and 8 days later (D8), following a single dose of HP, prior to adding paclitaxel. We performed RNA-sequencing on D1 and D8 tumor biopsies, identified genes associated with pCR using differential gene expression analysis, identified pathways associated with pCR using gene set enrichment and gene expression deconvolution methods, and compared the pCR predictive value of principal components derived from gene expression profiles by calculating and area under the curve for D1 and D8 subsets. Results: Twenty-three participants were enrolled, of whom 21 completed surgery following neoadjuvant therapy. Paired longitudinal fresh-frozen tumor samples (D1 and D8) were obtained from all patients. Among the 21 patients who underwent surgery, the pCR and the 4-year disease-free survival were 48% (90% CI 0.29-0.67) and 90% (95% CI 66-97%), respectively. The transcriptional profile of D8 biopsies was found to be more predictive of pCR (AUC = 0.91, 95% CI: 0.7993-1) than the D1 biopsies (AUC = 0.79, 95% CI: 0.5905-0.9822). Conclusions: In patients with HER2-positive IBC treated with neoadjuvant HP and paclitaxel for 16 weeks, gene expression patterns of tumor biopsies measured 1 week after treatment initiation not only offered different biological information but importantly served as a better predictor of pCR than baseline transcriptional analysis. Trial Registration: ClinicalTrials.gov identifier: NCT01796197 (https://clinicaltrials.gov/ct2/show/NCT01796197); registered on February 21, 2013.

HER2-low inflammatory breast cancer: Clinicopathologic features and prognostic implications.

BACKGROUND: HER2)-low expression is a predictive biomarker for novel anti-HER2 antibody-drug conjugates. However, little is known about its clinical significance in inflammatory breast cancer (IBC). METHODS: Patients diagnosed with HER2-negative IBC between December 1999 and December 2020 were identified from the Dana-Farber Cancer Institute IBC registry. Patients were divided into HER2-low (IHC 1+ or 2+/ISH-) and HER2-zero (IHC 0), comparing clinicopathologic features and disease outcomes between the two subgroups. RESULTS: The study included 276 patients. Among patients with stage III (n = 209) and stage IV (n = 67) IBC, 54% and 39% had HER2-low tumours, respectively. Oestrogen receptor (ER)-expressing tumours were more common in patients with HER2-low versus HER2-zero stage III IBC (65% versus 38%, p < 0.01). Among stage III patients undergoing surgery (n = 182), pathologic complete response (pCR) rates were higher for HER2-zero versus HER2-low IBC (11% versus 6%, OR: 1.8, 95%CI:0.6-5.3), but minimal differences persisted when separately analysing pCR by ER status. Similar invasive disease-free survival (iDFS) outcomes were observed among ER-positive HER2-zero versus HER2-low IBC (48-month iDFS: 63% versus 63%, HR: 1.10, 95%CI:0.57-2.13) and ER-negative HER2-zero versus HER2-low IBC (48-month iDFS: 28% versus 25%, HR: 1.19, 95%CI:0.69-2.04). Differences in overall survival (OS) were small, both among ER-positive HER2-zero versus HER2-low IBC (48-month OS: 80% versus 81%, HR: 0.82, 95%CI:0.39-1.73) and ER-negative HER2-zero versus HER2-low IBC (48-month OS: 34% versus 47%, HR: 1.34, 95%CI: 0.74-2.41). CONCLUSIONS: Marginal differences in clinicopathologic features and outcomes were observed in HER2-low versus HER2-zero IBC when controlling for ER status, not supporting the definition of HER2-low as a distinct subtype of IBC.

Lobular neoplasia detected at MRI-guided biopsy: imaging findings and outcomes.

OBJECTIVE: To review MRI findings of pure lobular neoplasia (LN) on MRI guided biopsy, evaluate surgical and clinical outcomes, and assess imaging findings predictive of upgrade to malignancy. METHODS: HIPAA compliant, IRB-approved retrospective review of our MRI-guided breast biopsy database from October 2008-January 2015. Biopsies yielding atypical lobular hyperplasia or lobular carcinoma in situ were included in the analysis; all biopsy slides were reviewed by a dedicated breast pathologist. Imaging indications, MRI findings, and histopathology were reviewed. Statistical analysis was performed using the two-tailed Fisher exact-test and the t-test, and 95% CIs were determined. A p < 0.05 was considered statistically significant. RESULTS: Database search yielded 943 biopsies in 785 patients of which 65/943 (6.9%) reported LN as the highest risk pathologic lesion. Of 65 cases, 32 were found to have LN as the dominant finding on pathology and constituted the study population. All 32 findings were mammographically and sonographically occult. Three of 32 (9.3%) cases of lobular neoplasia were upgraded to malignancy, all LCIS (one pleomorphic and two classical). The most common MRI finding was focal, heterogenous non-mass enhancement with low T2 signal. No clinical features or imaging findings were predictive of upgrade to malignancy. CONCLUSION: Incidence of pure lobular neoplasia on MRI guided biopsy is low, with comparatively low incidence of upgrade to malignancy. No imaging or clinical features are predictive of upgrade on surgical excision, therefore, prudent radiologic-pathologic correlation is necessary.

Pan-TRK Immunohistochemistry: A Useful Diagnostic Adjunct For Secretory Carcinoma of the Breast.

Secretory carcinoma is a special-type breast carcinoma underpinned by a recurrent t(12;15)(p13;q25) translocation resulting in ETV6-NTRK3 gene fusion. Immunohistochemistry (IHC) using a pan-TRK antibody has been recently shown to help identify NTRK rearrangements in other tumor types. The purpose of this study was to assess the diagnostic utility of pan-TRK IHC in secretory carcinoma of the breast. Pan-TRK IHC was performed using a rabbit monoclonal antibody on whole sections of 24 breast secretory carcinomas and tissue microarray sections of other breast carcinoma types (n=203) and histologic mimics (n=15). Cases were assessed for staining intensity and localization. The 24 patients with secretory carcinoma had a median age of 44 years and a median tumor size of 1.0 cm. ETV6 fluorescence in situ hybridization was positive in all cases tested (n=20). Twenty-three cases (95.8%) showed staining with pan-TRK, which was exclusively nuclear in 19, primarily nuclear with weak cytoplasmic staining in 3, and primarily cytoplasmic with focal nuclear staining in 1. The nuclear staining was diffuse in 17 and at least focally strong in 17. The only pan-TRK negative case was a core biopsy with limited tumor. Among the 203 nonsecretory carcinomas, 21 (10.3%) showed focal, weak nuclear staining in <5% of tumor cells and 1 (0.5%) showed focal membranous staining. All histologic mimics were negative. In conclusion, diffuse and/or at least focally strong nuclear pan-TRK staining is a sensitive and specific marker for secretory carcinoma of the breast.