Solid papillary carcinoma with reverse polarity of the breast harbors specific morphologic, immunohistochemical and molecular profile in comparison with other benign or malignant papillary lesions of the breast: a comparative study of 9 additional cases

Case report: Tall cell carcinoma with reversed polarity of the breast: an additional case and review of the literature

Objective

The aim of this report was to comprehensively investigate the clinicopathological features, histological characteristics, and differential diagnosis of tall cell carcinoma with reversed polarity of the breast (TCCRP) to enhance the understanding of this tumour for precise therapeutic interventions.

Methods

The clinicopathological characteristics and differential diagnosis of a patient with TCCRP were retrospectively analysed, and a systematic literature review was extracted from relevant published studies on PubMed.

Results

All patients included in the study were female, with a median age of 51 years. Microscopically, the tumour cells exhibited a solid papillary growth pattern with tall columnar morphology and reversed nuclear polarity. Immunohistochemistry revealed that the tumours were triple-negative breast cancer (negative for ER, PR, and HER-2), with a low Ki-67 proliferation index. Different degrees of expression were observed for CK7, Calretinin, and S-100 markers; however, CK5/6 showed high expression levels.

Conclusions

TCCRP is an uncommon invasive carcinoma subtype found in the breast. Its histological morphology resembles that of tall cell subtype papillary thyroid carcinoma. Accurate diagnosis requires the integration of histomorphological assessment along with immunohistochemistry and molecular genetics analysis.

[Reversed polarity high-cell carcinoma of the breast: A case report]

Reverse polarity high-cell carcinoma of the breast, formerly known as reverse polarity solid papillary carcinoma, is a rare entity recently introduced into the latest edition of the WHO classification of breast tumors. Its phenotype is triple-negative, and its diagnosis difficult. Although few cases have been reported in the literature, knowledge of this breast tumor is essential to distinguish it from other triple-negative carcinomas, which have a poorer prognosis. We report a case of high-cell, inverted-polarity carcinoma of the breast in a 43-year-old female patient with no history of breast neoplasia and no palpable mass on clinical examination. The tumour was discovered following a screening echomammogram, which revealed a lesion classified ACR 4b. A microbiopsy of this lesion concluded that it was a papillary proliferation that should be removed. A lumpectomy was performed. Histopathological and immunohistochemical studies of the surgical specimen confirmed the diagnosis of high-cell, reverse-polarity carcinoma expressing calretinin and IDH1. Given the rarity of this entity, there is no standard treatment. In our case, a mastectomy without lymph node curage was performed. The extension work-up was negative and the patient received no adjuvant treatment. After 12 months, the patient is in complete remission. In this case report, we describe the histopathological, immunohistochemical and molecular features of this rare entity.

The Role of Novel Immunohistochemical Markers for Special Types of Breast Carcinoma

Some histologic special types of breast carcinoma harbor specific recurrent genetic alterations that are not seen in other types of breast carcinoma (no special type), namely adenoid cystic carcinoma, secretory carcinoma, and tall cell carcinoma with reversed polarity. These tumors have unique morphologic features, are triple-negative, that is, do not express hormone receptors or HER2, and are generally associated with a favorable prognosis. Adenoid cystic carcinoma, like its counterpart in other organs, shows a MYB-NFIB fusion gene that is the result of a recurrent t(6;9)(q22-23;p23-24) translocation. Other MYB alterations have been described that result in overexpression of MYB . Secretory carcinoma is characterized by an ETV6-NTRK3 gene fusion that is the result of recurrent (12;15);(p13;q25) translocation, which is also seen in mammary analog secretory carcinoma of the salivary gland. Tall cell carcinoma with reversed polarity shows IDH2 p.Arg172 hotspot mutations. Immunohistochemical antibodies have emerged that identify the underlying genetic alterations in these tumors and serve as useful diagnostic tools. This review will provide an update on the molecular features and diagnostic immunohistochemical markers that have become increasingly popular to aid in diagnosing these uncommon triple-negative breast tumors.

Exome sequencing of affected duos and trios uncovers PRUNE2 as a novel prostate cancer predisposition gene

BACKGROUND

Prostate cancer (PrCa) is one of the most hereditable human cancers, however, only a small fraction of patients has been shown to carry deleterious variants in known cancer predisposition genes.

METHODS

Whole-exome sequencing was performed in multiple affected members of 45 PrCa families to select the best candidate genes behind part of the PrCa missing hereditability. Recurrently mutated genes were prioritised, and further investigated by targeted next-generation sequencing in the whole early-onset and/or familial PrCa series of 462 patients.

RESULTS

PRUNE2 stood out from our analysis when also considering the available data on its association with PrCa development. Ten germline pathogenic/likely pathogenic variants in the PRUNE2 gene were identified in 13 patients. The most frequent variant was found in three unrelated patients and identical-by-descent analysis revealed that the haplotype associated with the variant is shared by all the variant carriers, supporting the existence of a common ancestor.

DISCUSSION

This is the first report of pathogenic/likely pathogenic germline variants in PRUNE2 in PrCa patients, namely in those with early-onset/familial disease. Importantly, PRUNE2 was the most frequently mutated gene in the whole series, with a deleterious germline variant identified in 2.8% of the patients, representing a novel prostate cancer predisposition gene.

IDH2 -Mutated Sinonasal Tumors: A Review

INTRODUCTION

Genetic profiling has caused an explosion in the subclassification of sinonasal malignancies. Distinguishing several of these tumor types by histomorphology alone has been quite challenging, and although pathologic classification aims to be as specific as possible, it remains to be seen if this recent move toward tumor speciation bears clinical relevance, most particularly focused on subtyping for the sake of prognostication and treatment. One such recently described cohort, predominantly lumped under the moniker of sinonasal undifferentiated carcinoma (SNUC) is IDH2 -mutated sinonasal carcinoma, a high-grade carcinoma associated with mutations in the isocitrate dehydrogenase-2 ( IDH2 ) gene. A hotspot mutation in the R172 codon has been described in 50% to 80% of the tumors classified as SNUC, large cell neuroendocrine carcinomas, and rarely in cases classified as olfactory neuroblastoma. The use of immunohistochemical and molecular approaches is required to correctly identify this subset of sinonasal tumors, with further study necessary to elucidate their unique pathophysiology, ultimately determining whether a revision is required toward the current therapeutic approach.

AIMS

Here, we provide an overview of the IDH2- mutated sinonasal tumors, discuss histopathologic and clinical features, and focus on molecular diagnostics and novel immunohistochemical markers.

RESULTS

A review of the literature reveals 82 reported cases with IDH2 -mutated sinonasal tumors (IST), confirmed either by molecular studies or diagnostic immunohistochemical markers. The mean patient age is 60 years (female/male: 1/1.4), the median tumor size is 5 cm (range: 2.5 to 7.0 cm), and the most common location is the nasal cavity (81%). IST displays tumor necrosis and increased mitotes. Histopathologically, IST shows SNUC-like, large cell neuroendocrine carcinomas-like, or poorly differentiated carcinoma-like features (77%, 12%, and 9%, respectively). The molecular hotspot alterations in mitochondrial IDH2 are: R172S (61%), R172T (19%), R172G (7%), and R172M (3%). Sixty-five percent of tumors are surgically resectable, and all patients received chemotherapy, radiation therapy, or both. Rates of locoregional recurrence and distant metastasis are 60% and 40%, respectively. One-, 3- and 5-year survival rates are 83%, 50%, and 43%, respectively. In all but 1 study, IST is associated with better outcomes than IDH2 wild-type tumors and SMARCB1 -deficient sinonasal tumors.

Recurrent IDH2 Mutations in Salivary Gland Striated Duct Adenoma Define an Expanded Histologic Spectrum Distinct From Canalicular Adenoma

Striated duct adenoma (SDA) is a rare salivary gland neoplasm defined by histologic similarity to normal striated ducts. However, doubt persists about whether SDA represents a genuine entity distinct from canalicular adenoma and if a malignant counterpart exists. This study aims to evaluate the molecular underpinnings of SDA to clarify its pathogenesis and classification. We identified 10 SDA and 2 tumors called low-grade adenocarcinoma not otherwise specified that were retrospectively recognized to resemble SDA. All cases showed recurrent histologic features including (1) discrete monophasic tubules, (2) tall columnar eosinophilic cells, (3) monotonous oval nuclei, and (4) scant fibrous stroma, and most were positive for S100 protein (91%), SOX10 (80%), and CK7 (80%). Although 1 case was previously called adenocarcinoma based on interdigitation with normal acini, this pattern was also seen in some SDA, and likely does not indicate malignancy; the significance of growth surrounding nerve in 1 other case is less clear. Targeted sequencing identified IDH2 R172X mutations in all 8 cases with sufficient tissue, with positivity for IDH1/2 mutation-specific immunohistochemistry in 9 cases stained. In contrast, 5 canalicular adenomas lacked IDH2 mutations or other oncogenic alterations. Overall, IDH2 R172X mutations are a defining feature of SDA that, in combination with its recognizable pathologic profile, confirm it is a unique entity separate from canalicular adenoma. IDH1/2 mutation-specific immunohistochemistry may provide a convenient tool to facilitate diagnosis. Both morphology and IDH2 mutations raise parallels between SDA and breast tall cell carcinoma with reverse polarity.

Dysregulation of the PRUNE2/PCA3 genetic axis in human prostate cancer: from experimental discovery to validation in two independent patient cohorts

Background

We have previously shown that the long non-coding (lnc)RNA prostate cancer associated 3 (PCA3; formerly prostate cancer antigen 3) functions as a trans-dominant negative oncogene by targeting the previously unrecognized prostate cancer suppressor gene PRUNE2 (a homolog of the Drosophila prune gene), thereby forming a functional unit within a unique allelic locus in human cells. Here, we investigated the PCA3/PRUNE2 regulatory axis from early (tumorigenic) to late (biochemical recurrence) genetic events during human prostate cancer progression.

Methods

The reciprocal PCA3 and PRUNE2 gene expression relationship in paired prostate cancer and adjacent normal prostate was analyzed in two independent retrospective cohorts of clinically annotated cases post-radical prostatectomy: a single-institutional discovery cohort (n=107) and a multi-institutional validation cohort (n=497). We compared the tumor gene expression of PCA3 and PRUNE2 to their corresponding expression in the normal prostate. We also serially examined clinical/pathological variables including time to disease recurrence.

Results

We consistently observed increased expression of PCA3 and decreased expression of PRUNE2 in prostate cancer compared with the adjacent normal prostate across all tumor grades and stages. However, there was no association between the relative gene expression levels of PCA3 or PRUNE2 and time to disease recurrence, independent of tumor grades and stages.

Conclusions

We concluded that upregulation of the lncRNA PCA3 and targeted downregulation of the protein-coding PRUNE2 gene in prostate cancer could be early (rather than late) molecular events in the progression of human prostate tumorigenesis but are not associated with biochemical recurrence. Further studies of PCA3/PRUNE2 dysregulation are warranted.

Funding

We received support from the Human Tissue Repository and Tissue Analysis Shared Resource from the Department of Pathology of the University of New Mexico School of Medicine and a pilot award from the University of New Mexico Comprehensive Cancer Center. RP and WA were supported by awards from the Levy-Longenbaugh Donor-Advised Fund and the Prostate Cancer Foundation. EDN reports research fellowship support from the Brazilian National Council for Scientific and Technological Development (CNPq), Brazil, and the Associação Beneficente Alzira Denise Hertzog Silva (ABADHS), Brazil. This work has been funded in part by the NCI Cancer Center Support Grants (CCSG; P30) to the University of New Mexico Comprehensive Cancer Center (CA118100) and the Rutgers Cancer Institute of New Jersey (CA072720).

Novel markers in breast pathology

Breast pathology is an ever-expanding database of information which includes markers, or biomarkers, that detect or help treat the disease as prognostic or predictive information. This review focuses on these aspects of biomarkers which are grounded in immunohistochemistry, liquid biopsies and next-generation sequencing.

The Diagnostic Utility of IDH2 R172 Immunohistochemistry in Tall Cell Carcinoma With Reversed Polarity of the Breast

Tall cell carcinoma with reversed polarity (TCCRP) is a rare histologic type of low-grade breast cancer, consisting of tall columnar cells with reversed nuclear polarity and characterized by frequent IDH2 mutations. We herein report 3 cases of TCCRP with sequencing analyses of the IDH2 gene and immunohistochemical examination using monoclonal antibodies (11C8B1) against IDH2 R172. IDH2 R172 mutations were detected in all 3 resected tumors (R172S in 2 tumors and R172T in 1 tumor), and the presence of these mutations was confirmed by IDH2 R172 immunohistochemistry. Tumor cells of TCCRP showed strong and diffuse staining for the antibody against IDH2 R172. In 1 case, tumor tissue from 2 core needle biopsy samples collected on different days were also immunohistochemically positive for IDH2 R172. These results indicate that IDH2 R172 immunohistochemistry is suitable for the detection of TCCRP in both resection and biopsy samples. In addition, a literature review revealed that R172S and R172T account for 76% of IDH2 mutations in TCCRP, suggesting that 11C8B1, which reacts with R172S and R172T, was likely most sensitive for IDH2-mutated TCCRP among many available antibodies for IDH2 R172. Furthermore, the combination of 2 or more antibodies against IDH2 R172 could be more effective for detecting TCCRP mutation. However, it is important to note that IDH2 R172 immunohistochemistry is not absolute, because IDH2 wild type is found in a small proportion (10%) of cases, and a few cases of IDH2-mutated TCCRP may harbor rare subtypes of R172 that are not covered by available antibodies.

Papillary lesions of the breast - review and practical issues

Papillary lesions of the breast represent a heterogeneous group of neoplasm featuring fibrovascular cores covered by epithelial cells with or without intervening myoepithelial cells. According to the World Health Organization classification of breast tumors, papillary lesions of the breast are further classified into intraductal papilloma (including intraductal papilloma with atypical ductal hyperplasia /ductal carcinoma in situ), papillary ductal carcinoma in situ, encapsulated papillary carcinoma, solid papillary carcinoma (in situ and invasive) and invasive papillary carcinoma. The overlapping morphological features and immunohistochemical profiles make accurate diagnosis of breast papillary lesion a challenge for pathologists. In this review, the morphological and relevant immunohistochemical features of papillary lesions are discussed, with further emphasis on some commonly encountered practical diagnostic issues. A simple diagnostic algorithm will be established. The relevant molecular characteristics will be discussed as well.

Special Histologic Type and Rare Breast Tumors - Diagnostic Review and Clinico-Pathological Implications

Breast cancer is the most common malignant tumor in females. While most carcinomas are categorized as invasive carcinoma, no special type (NST), a diverse group of tumors with distinct pathologic and clinical features is also recognized, ranging in incidence from relatively more common to rare. So-called "special histologic type" tumors display more than 90% of a specific, distinctive histologic pattern, while a spectrum of tumors more often encountered in the salivary gland may also arise in the breast. Metaplastic carcinomas can present diagnostic challenges. Some uncommon tumors harbor pathognomonic genetic alterations. This article provides an overview of the key diagnostic points and differential diagnoses for this group of disparate lesions, as well as the salient clinical characteristics of each entity.

OncoSNIPE® Study Protocol, a study of molecular profiles associated with development of resistance in solid cancer patients

Background

Nowadays, evaluation of the efficacy and the duration of treatment, in context of monitoring patients with solid tumors, is based on the RECIST methodology. With these criteria, resistance and/or insensitivity are defined as tumor non-response which does not allow a good understanding of the diversity of the underlying mechanisms. The main objective of the OncoSNIPE® collaborative clinical research program is to identify early and late markers of resistance to treatment.

Methods

Multicentric, interventional study with the primary objective to identify early and / or late markers of resistance to treatment, in 600 adult patients with locally advanced or metastatic triple negative or Luminal B breast cancer, non-small-cell lung cancer or pancreatic ductal adenocarcinoma. Patients targeted in this study have all rapid progression of their pathology, making it possible to obtain models for evaluating markers of early and / or late responses over the 2-year period of follow-up, and thus provide the information necessary to understand resistance mechanisms. To explore the phenomena of resistance, during therapeutic response and / or progression of the pathology, we will use a multidisciplinary approach including high-throughput sequencing (Exome-seq and RNAseq), clinical data, medical images and immunological profile by ELISA. Patients will have long-term follow-up with different biological samples, at baseline (blood and biopsy) and at each tumoral evaluation or tumoral progression evaluated by medical imaging. Clinical data will be collected through a dedicated Case Report Form (CRF) and enriched by semantic extraction based on the French ConSoRe (Continuum Soins Recherche) initiative, a dedicated Semantic Clinical Data Warehouse (SCDW) to cancer.

The study is sponsored by Oncodesign (Dijon, France) and is currently ongoing.

Discussion

The great diversity of intrinsic or acquired molecular mechanisms involved in resistance to treatment constitutes a real therapeutic issue. Improving understanding of mechanisms of resistance of cancer cells to anti-tumor treatments is therefore a major challenge. The OncoSNIPE cohort will lead to a better understanding of the mechanisms of resistance and will allow to explore new mechanisms of actions and to discover new therapeutic targets or strategies making it possible to circumvent the escape in different types of cancer.

Trial registration

Clinicaltrial.gov. Registered 16 September 2020, https://clinicaltrials.gov/ct2/show/NCT04548960?term=oncosnipe&draw=2&rank=1 and ANSM ID RCB 2017-A02018-45.

Low-grade triple-negative breast carcinomas. A report of 2 cases and an update of current concepts

Triple negative breast cancer is defined by the lack of expression of estrogen, progesterone and HER2 receptors. Significant molecular, morphological and clinical heterogeneity is present in this group of neoplasms. Although the majority are high-grade tumors, low-grade triple negative breast cancers can occur and their evolution, molecular characteristics and therapeutic management vary from the former. In the current review, we focus on the histological and immunohistochemical phenotypes of two new low-grade cases: an acinic cell carcinoma and an adenoid cystic carcinoma. Data originated from the pathology department of a third-level hospital over an 18-month period, within a breast cancer screening program. Low-grade triple negative cancers should be suspected in triple negative breast cancers with low proliferative rates as, unlike high-grade tumors, they require a multidisciplinary approach. They can be diagnosed at an early stage by immunohistochemistry using core needle biopsy.

Papillary lesions of the breast

Papillary lesions of the breast represent a heterogeneous group of lesions including benign papillomas, papillomas with focal epithelial atypia, fully fledged ductal carcinoma in situ (DCIS) or lobular neoplasia, papillary DCIS, encapsulated papillary carcinomas without or with invasion, solid papillary carcinomas, and invasive papillary carcinomas. A micropapillary pattern characterized by lack of fibrous stalks within the papillae is observed in micropapillary DCIS and invasive micropapillary carcinoma. In addition, a variety of other rare breast lesions reveals a papillary architecture such as tall cell carcinoma with reversed polarity (TCCRP) and mucinous cystadenocarcinoma, adenomyoepithelioma, and secretory carcinoma. In addition, benign lesions such as usual ductal hyperplasia, apocrine metaplasia, gynecomastia, and juvenile papillomatosis may show a papillary or micropapillary architecture. Fragments of a benign papilloma in a breast biopsy are considered a lesion of uncertain malignant potential (B3 in the European classification) and excision is mostly recommended. Although the knowledge about molecular pathology of papillary breast lesions has increased, there is not sufficient evidence for diagnostically useful molecular features, yet. The aim of this review is to provide an update on papillary and micropapillary lesions with emphasis on problematic areas for daily diagnostic work including biopsies.

Triple-Negative Breast Cancer Histological Subtypes with a Favourable Prognosis

Simple Summary

Breast cancers that lack expression of the predictive markers oestrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 are known as triple-negative breast cancers (TNBCs) and are generally considered to have a poor prognosis. As available targeted treatments are not effective, aggressive chemotherapy is frequently advocated for patients with TNBC. It is now becoming apparent that TNBC is not one entity but constitutes a range of malignancies with different clinical behaviour. This paper reviews 7 distinct histological subtypes of TNBC where the overall prognosis is favourable, and aggressive systemic treatment is generally not indicated. Their recognition and separation from the larger group of no special type TNBC are important. The members of the European Working Group for Breast Screening Pathology review the morphology, known molecular features and reported outcomes, and formulate a consensus statement regarding the approach to the subtypes that are associated with a favourable prognosis.

Abstract

Triple-negative breast cancers (TNBC), as a group of tumours, have a worse prognosis than stage-matched non-TNBC and lack the benefits of routinely available targeted therapy. However, TNBC is a heterogeneous group of neoplasms, which includes some special type carcinomas with a relatively indolent course. This review on behalf of the European Working Group for Breast Screening Pathology reviews the literature on the special histological types of BC that are reported to have a triple negative phenotype and indolent behaviour. These include adenoid cystic carcinoma of classical type, low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, low-grade mucoepidermoid carcinoma, secretory carcinoma, acinic cell carcinoma, and tall cell carcinoma with reversed polarity. The pathological and known molecular features as well as clinical data including treatment and prognosis of these special TNBC subtypes are summarised and it is concluded that many patients with these rare TNBC pure subtypes are unlikely to benefit from systemic chemotherapy. A consensus statement of the working group relating to the multidisciplinary approach and treatment of these rare tumour types concludes the review.

Tall cell carcinoma with reversed polarity: case report with gene sequencing and literature review

Tall cell carcinoma with reversed polarity (TCCRP) is an extremely rare type of invasive breast cancer with only 17 literatures and 75 cases reported. Knowledge on TCCRP is still scanty. The present study reported 2 cases of TCCRP, analyzed their clinicopathological characteristics, and used whole exome sequencing to perform genetic testing. Both two cases were proved to have typical clinicopathological manifestations (solid and papillary architectures lined by tall columnar cells with nuclei displaying "reverse polarization") and hotspot mutations (IDH2 and PIK3CA mutations) of TCCRP. Furthermore, positive expression of TTF-1 was found in a small number of tumor cells nuclei and normal ductal epithelial cells, while the negative rate of TTF-1 in previous case reports was 100%. Attention should be paid in core needle biopsy to avoid misdiagnosis. In addition, this article also reviewed all previous cases and demonstrated that the positive expression of calretinin might have an indicative significance for TCCRP, which could be used as one of the auxiliary diagnosis tools. The diagnosis of TCCRP requires comprehensive analysis of clinical pathology and genetic testing results. There is no clear treatment standard for TCCRP currently, further research should be reported to characterize and deeply investigate the diagnosis and treatment criteria of TCCRP.

Tall Cell Carcinoma With Reversed Polarity of the Breast

Tall cell carcinoma with reversed polarity (TCCRP) of the breast is a rare entity with low potential for malignancy that exhibits some morphological similarities to the tall cell variant of papillary thyroid carcinoma. Immunohistochemical and molecular studies help establish the mammary origin of this neoplasm. Here, we describe the case of a 63-year-old woman with a finding of a nodular lesion during a screening mammogram, whose morphological findings and immunohistochemical studies confirmed the diagnosis of papillary high cell carcinoma with the reverse polarity of the mammary gland.

Breast carcinomas of low malignant potential

Some breast carcinomas have a very low likelihood of metastasis to regional lymph nodes and distant sites and may be considered carcinomas of low malignant potential. In this article, we review the clinical, pathologic, immunophenotypic, and molecular features of selected breast carcinomas of low malignant potential including low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, encapsulated papillary carcinoma, solid papillary carcinoma, and tall cell carcinoma with reversed polarity.

Triple-negative breast lobular carcinoma: a luminal androgen receptor carcinoma with specific ESRRA mutations

Primary triple-negative invasive lobular breast carcinomas (TN-ILCs), which do not express hormone receptors and HER2 at diagnosis, are rare and poorly known. In this study, we analyzed the largest TN-ILC series ever reported in the literature, in comparison to phenotypically similar breast tumor subtypes: triple-negative invasive ductal carcinoma (TN-IDC) and hormone receptor-positive invasive lobular carcinoma (HR + ILC). All primary TN-ILCs registered in our database between 2000 and 2018 (n = 38) were compared to tumors from control groups, matched by stage and Elston/Ellis grade, with regard to clinical, pathologic, and immunohistochemical characteristics. A comparative molecular analysis (whole-exome and RNA sequencing using next-generation technology) was also performed. We found that TN-ILC patients were older than those with HR + ILC (P = 0.002) or TN-IDC (P < 0.001). Morphologically, TN-ILCs had aggressive phenotypes, with more pleomorphism (P = 0.003) and higher nuclear grades than HR + ILCs (P = 0.009). Immunohistochemistry showed that TN-ILCs less frequently expressed basal markers (CK5/6, EGFR and SOX10) than TN-IDCs (P < 0.001), while androgen receptor (AR) positivity was more prevalent (P < 0.001). Survival curves analysis did not show differences between TN-ILC and TN-IDC patients, while overall and distant metastasis-free survival were significantly worse compared to those with HR + ILCs (P = 0.047 and P = 0.039, respectively). At a molecular level, we found that TN-ILCs had particular transcriptomic profiles, characterized by increased AR signaling, and associated with frequent alterations in the PI3K network and ERBB2. Interestingly, whole-exome analysis also identified three specific recurrent ESRRA hotspot mutations in these tumors, which have never been described in breast cancer to date and which were absent in the other two tumor subtypes. Our findings highlight that TN-ILC is a unique aggressive breast cancer associated with elderly age, which belong to the luminal androgen receptor subtype as determined by immunohistochemistry and transcriptomic profiling. Moreover, it harbors specific molecular alterations (PI3K, ERBB2 and ESRRA) which may pave the way for new targeted therapeutic strategies.

An Algorithm Combining Patient Performance Status, Second Hit Analysis, PROVEAN and Dann Prediction Tools Could Foretell Sensitization to PARP Inhibitors in Digestive, Skin, Ovarian and Breast Cancers

Simple Summary

PARP inhibitors, a family of targeted cancer therapeutics, have been shown to be efficient in patients with some deficiencies in the homologous recombination machinery. However, a quick and reliable identification of patients who would benefit from such therapies remains a challenge. In particular, patients with tumors carrying variants of unknown significance (VUS) in homologous recombination genes do not currently benefit from PARP inhibitor treatments. In this study, we present an algorithm that may allow classification of these variants with regard to their impact on tumor responsiveness to PARP inhibitors. If validated on a larger patient sample, our algorithm would allow patients with tumors potentially responsive to PARP inhibitors to benefit from this therapy.

Abstract

PARP inhibitors yield interesting outcomes for patients with ovarian tumors harboring BRCA1 or BRCA2 mutation, but also with other tumors with homologous repair (HR) deficiency. About 40% of variants are variants of unknown significance (VUS), blocking the use of PARP inhibitors. In this study, we analyzed NGS data from 78 metastatic patients treated with PARP inhibitors. We tested NGS data and in silico predictions to classify VUS as potentially benign or deleterious. Among 41 patients treated with olaparib, three had tumors harboring benign and 26 pathogenic variants, while 12 had VUS. Progression-Free Survival (PFS) analysis showed that benign variants did not respond to olaparib whereas pathogenic variants were associated with a median PFS of 190 days. Surprisingly, median PFS of patients with VUS-carrying tumors suggested that some of them may be sensitive to PARP inhibitors. By testing different in silico predictions and variant allelic frequency, we obtained an algorithm predicting VUS sensitivity to PARP inhibitors for patients with a Performance Status below 3. Our work suggests that VUS in HR genes could be predicted as benign or deleterious, which may increase the number of patients eligible for PARP inhibitor treatment. Further studies in a larger sample are warranted to validate our prediction algorithm.

Papillary neoplasms of the breast-reviewing the spectrum

Papillary neoplasms of the breast encompass a wide range of tumor types ranging from the benign intraductal papilloma to in situ and invasive papillary carcinomas. In this review, we considered each tumor entity listed under the Papillary Neoplasms category in the latest WHO Classification of Breast Tumors (5th edition), namely intraductal papilloma, papillary ductal carcinoma in situ, encapsulated papillary carcinoma, solid-papillary carcinoma, and invasive papillary carcinoma. We examined their pathological features, current issues pertaining to diagnosis and prognostication, as well as the latest molecular findings. We also briefly addressed adenomyoepithelioma and the newly included tall cell carcinoma with reversed polarity, highlighting areas where they overlap with papillary neoplasms.

ER-/PR+ breast cancer: A distinct entity, which is morphologically and molecularly close to triple-negative breast cancer

Determining the status of steroid hormone receptors [oestrogen (ER) and progesterone receptors (PR)] is a crucial part of the breast cancer workup. Thereby, breast cancers can be classified into four subtypes. However, the existence of ER-/PR+ tumours, often reported to be ill-classified due to technical errors, remains controversial. In order to address this controversy, we reviewed the hormone receptor status of 49 breast tumours previously classified as ER-/PR+ by immunohistochemistry, and compared clinical, pathological and molecular characteristics of confirmed ER-/PR+ tumours with those of ER+ and triple-negative tumours. We unequivocally confirmed the ER-/PR+ status in 27 of 49 tumours (0.3% of all breast cancers diagnosed in our institution between 2000 and 2014). We found that ER-/PR+ were morphologically and histologically similar to triple-negative tumours, but very distinct from ER+ tumours, with more aggressive phenotypes and more frequent basal marker expression than the latter. On the molecular level, RNA sequencing revealed different gene expression profiles between the three groups. Of particular interest, several genes controlled by the suppressor of zest 12 (SUZ12) were upregulated in ER-/PR+ tumours. Overall, our results confirm that ER-/PR+ breast cancers are an extremely rare but 'real' tumour subtype that requires careful diagnosis and has distinct features warranting different responsiveness to therapies and different clinical outcomes. Studies on larger cohorts are needed to further characterise these tumours. The likely involvement of SUZ12 in their biology is an interesting finding which may - in a long run - give rise to the development of new therapeutic alternatives.

Tall cell carcinoma with reversed polarity: A case report of a very rare breast tumor entity and mini-review

Tall cell carcinoma with reversed polarity (TCCRP) is a very rare variant of carcinoma of the breast, resembling the tall cell variant of papillary thyroid carcinoma, first described in 2003, recently recognized as a separate entity in the 5th edition of the WHO (World Health Organization) Blue Book Classification of breast tumors with alternative terminology of tall cell variant of papillary breast carcinoma and solid papillary carcinoma with reversed polarity. Here, we report an additional case of this rare tumor in a 71-year-old woman, and the problems correlating with its diagnosis.

Tall cell carcinoma of the breast with reverse polarity: case report with gene sequencing and literature review

Tall cell carcinoma of the breast with reverse polarity (TCCRP), described firstly and also known as tall cell variant of papillary breast carcinoma (TCVPBC), is a rare type of breast cancer that mimics papillary thyroid carcinoma (PTC) histopathologically. As the incidence of this type of tumor is very low, awareness of it is crucial to ensuring that unnecessary clinical investigations are avoided. The present study examined a 45-year-old woman in China who was diagnosed with TCCRP. This paper outlines her demographic and clinicopathologic data, and her follow-up and immunohistochemical examination results. Furthermore, this study used the next-generation sequencing (NGS) technique to identify concurrent isocitrate dehydrogenase 2 (IDH2) and phosphatidylinositol 3-kinase catalytic alpha (PIK3CA) hotspot mutations. Notably, the novel results of the study showed that the IDH2 R120 (rather than the IDH2 R172) mutation may also be present in this disease. Additionally, a comprehensive literature review was conducted to elucidate some of the significant clinical and pathological features of this type of disease. This information may provide important insights that can be used in diagnosis and treatment. It is essential both for physicians and pathologists to recognize the existence of TCCRP, with its own specific clinical and pathological characteristics. Further research using molecular biology techniques should be conducted in the future to characterize this unique entity.

Tall Cell Carcinoma with Reverse Polarity of Breast: Report of a Case with Unique Morphologic and Molecular Features

Breast carcinomas are a heterogeneous group of malignancy, having variable clinical outcomes depending on their cellular and molecular properties. Tall cell carcinoma with reverse polarity (TCCRP) is a recently described rare entity, which shares morphological features with tall cell variant of papillary thyroid carcinoma but has a distinct morphological, immunohistochemical, and molecular profile. We describe a case of a 40-year-old female patient, who presented with lump in the breast. The patient underwent lumpectomy and was diagnosed as tall cell carcinoma with reverse polarity. Immunohistochemistry and bi-directional Sanger sequencing for IDH2 mutation were used for diagnosis. Tall cell carcinoma with reverse polarity is a rare and newly described entity with characteristic morphological and molecular findings, which carries an excellent prognosis.

Novel uses of immunohistochemistry in breast pathology: interpretation and pitfalls

Immunohistochemistry is an essential component of diagnostic breast pathology. The emergence of novel assays and applications is accompanied by new interpretation criteria and potential pitfalls. Immunohistochemistry assists in supporting breast origin for primary or metastatic carcinomas and identifying non-mammary metastases to the breast; however, no single immunostain is perfectly sensitive nor specific. GATA3 and Sox10 are particularly useful immunostains to identify triple negative breast carcinoma, which are often negative for other markers of mammary differentiation. Sox10 labeling is a major potential diagnostic pitfall, as Sox10 and S-100 label both triple negative breast carcinoma and metastatic melanoma; a pan-cytokeratin immunostain should always be included for this differential diagnosis. Novel immunohistochemistry serves as surrogates for the molecular alterations unique to several of special-type breast carcinomas, including the use of MYB in adenoid cystic carcinoma, pan-TRK in secretory carcinoma, and mutant IDH2 in tall cell carcinoma with reversed polarity (TCCRP). In addition, PD-L1 immunohistochemistry is an emerging, albeit imperfect, biomarker for breast cancer immunotherapy, with different assay parameters and scoring criteria in breast carcinoma compared to other tumor types. The expanding repertoire of novel immunohistochemistry provides additional diagnostic tools and biomarkers that improve diagnostic breast pathology and patient care.

Problematic breast tumors reassessed in light of novel molecular data

Breast cancer is a vastly heterogeneous disease encompassing a panoply of special histological subtypes. Although rare breast tumors have largely not been investigated systematically in large scale genomics series, recent studies have shed light on the genetic underpinnings of special histologic subtypes of breast cancer. Genomic analyses of estrogen receptor-positive special histologic types of breast cancer have not resulted in the identification of novel pathognomonic genetic alterations in addition to the confirmation of the presence of CDH1 loss-of-function mutations in invasive lobular carcinomas. By contrast, the analyses of triple-negative breast cancers have demonstrated that low-grade triple-negative breast cancers categorically differ from the common forms of high-grade triple-negative disease biologically and phenotypically and are underpinned by specific fusion genes or hotspot mutations. A subset of low-grade triple-negative disease has been shown to harbor highly recurrent if not pathognomonic genetic alterations, such as ETV6-NTRK3 fusion gene in secretory carcinomas, the MYB-NFIB fusion gene, MYBL1 rearrangements or MYB gene amplification in adenoid cystic carcinomas, and HRAS Q61 hotspot mutations coupled with mutations in PI3K pathway genes in estrogen receptor-negative adenomyoepitheliomas. A subset of these pathognomonic genetic alterations (e.g., NTRK1/2/3 fusion genes) now constitute an FDA approved indication for the use of TRK inhibitors in the advanced/metastatic setting. These studies have also corroborated that salivary gland-like tumors of the breast, other than acinic cell carcinomas, harbor the repertoire of somatic genetic alterations detected in their salivary gland counterparts. Reassuringly, the systematic study of special histologic types of breast cancer utilizing state-of-the-art sequencing approaches, rather than rendering pathology obsolete, has actually strengthened the importance of breast cancer histologic typing and is providing additional ancillary markers for the diagnosis of these rare but fascinating entities.

Villin is a biomarker for reverse polarity in colorectal micropapillary carcinoma

Colorectal cancer (CRC) is a common malignant tumor of digestive system. CRC with micropapillary pattern (MPP) is an aggressive variant of colorectal adenocarcinoma. The aim of the present study was to clarify the clinicopathological significance and the prognostic role of an immunohistochemical marker, MPP, in CRC. The association between MPP and clinicopathological characteristics and prognosis in 286 cases of CRC (286/453 cases had follow-up information) were analysed. Then, 81 tissues without MPP and 90 tissues with MPP were analysed by immunohistochemistry using antibodies against villin, E-cadherin and epithelial membrane antigen (EMA). Bioinformatics was used to evaluate the expression of these three indicators in CRC. The proportion of micropapillary carcinoma in the overall tumour was ≥5%, and was observed in 90/453 cases (19.8%). The present data showed that CRC with MPP displayed higher rates of vascular and lymphatic invasion, a higher metastatic lymph node ratio and a higher pathological tumour and metastasis stage compared with CRC without MPP. The positive expression rates of EMA, E-cadherin and villin were 50.3, 93.4 and 96.5%, respectively. In 90 CRC cases with MPP, EMA inside-out pattern (I/OP) staining was observed in 26 cases (28.9%), and it was often focal and partial, while 37 cases (41.1%) had E-cadherin focal and partial staining compatible with reverse polarity. Villin I/OP staining was observed in 77 cases (85.6%), and circumferential staining predominated over partial staining. Overall, the data suggested that the presence of MPP is significantly associated with aggressive tumour behaviour and worse overall survival rate in CRC. Visualization and distinction of reverse polarity of colorectal micropapillary carcinomas is improved villin compared with EMA or E-cadherin.

Histological Aspects and Quantitative Assessment of Ki67 as Prognostic Factors in Breast Cancer Patients: Result from a Single-Center, Cross Sectional Study

Background and objectives: Our aim is to explore the relationship between the levels of protein encoded by Ki67 and the histopathological aspects regarding the overall survival and progression-free survival in a single university center. A secondary objective was to examine other factors that can influence these endpoints. New approaches to the prognostic assessment of breast cancer have come from molecular profiling studies. Ki67 is a nuclear protein associated with cell proliferation. Together with the histological type and tumor grade, it is used to appreciate the aggressiveness of the breast tumors. Materials and Methods: We conducted a retrospective single-institution study, at Elias University Emergency Hospital, Bucharest, Romania, in which we enrolled women with stage I to III breast cancer. The protocol was amended to include the immunohistochemistry determination of Ki67 and the histological aspects. The methodology consisted in using a Kaplan-Meier analysis for the entire sample and restricted mean survival time up to 36 months. Results: Both lower Ki67 and low tumor grade are associated with better prognosis in terms of overall survival (OS) and progression-free survival (PFS) for our patients' cohort. In our group, the histological type did not impact the time to progression or survival. Conclusions: Both overall survival and progression-free survival may be influenced by the higher value of Ki67 and less differentiated tumors. Further studies are needed in order to establish if the histologic type may impact breast cancer prognostic, probably together with other histologic and molecular markers.

Immunohistochemical analysis of IDH2 R172 hotspot mutations in breast papillary neoplasms: applications in the diagnosis of tall cell carcinoma with reverse polarity

Tall cell carcinoma with reverse polarity is a rare subtype of breast carcinoma with solid and papillary growth and nuclear features reminiscent of those of the tall cell variant of papillary thyroid carcinoma. These tumors harbor recurrent IDH2 R172 hotspot mutations or TET2 mutations, co-occurring with mutations in PI3K pathway genes. Diagnosis of tall cell carcinomas with reverse polarity is challenging in view of their rarity and the range of differential diagnosis. We sought to determine the sensitivity and specificity of IDH2 R172 immunohistochemistry for the detection of IDH2 R172 hotspot mutations in this entity. We evaluated 14 tall cell carcinomas with reverse polarity (ten excision and five core needle biopsy specimens), 13 intraductal papillomas, 16 solid papillary carcinomas, and 5 encapsulated papillary carcinomas by Sanger sequencing of the IDH2 R172 hotspot locus and of exons 9 and 20 of PIK3CA, and by immunohistochemistry using monoclonal antibodies (11C8B1) to the IDH2 R172S mutation. The 14 tall cell carcinomas with reverse polarity studied harbored IDH2 R172 hotspot mutations, which co-occurred with PIK3CA hotspot mutations in 50% of cases. None of the other papillary neoplasms analyzed displayed IDH2 R172 mutations, however PIK3CA hotspot mutations were detected in 54% of intraductal papillomas, 6% of solid papillary carcinomas, and 20% of encapsulated papillary carcinomas tested. Immunohistochemical analysis with anti-IDH2 R172S antibodies (11C8B1) detected IDH2 R172 mutated protein in 93% (14/15) of tall cell carcinomas with reverse polarity samples including excision (n = 9/10) and core needle biopsy specimens (n = 5), whereas the remaining papillary neoplasms (n = 34) were negative. Our findings demonstrate that immunohistochemical analysis of IDH2 R172 is highly sensitive and specific for the detection of IDH2 R172 hotspot mutations, and likely suitable as a diagnostic tool in the evaluation of excision and core needle biopsy material of tall cell carcinomas with reverse polarity.

Solid-type adenoid cystic carcinoma of the breast, a distinct molecular entity enriched in NOTCH and CREBBP mutations

Adenoid cystic carcinoma (ACC) of the breast with a predominant solid pattern is difficult to diagnose with certainty and differentiate from more common triple-negative breast cancers (TNBCs) of basal-phenotype. To better characterize solid ACC, we performed a clinical, morphological, immunohistochemical, and molecular comparative analysis of 33 ACCs of the breast comprising 17 solid variant ACCs and 16 conventional ACCs. Solid ACCs displayed basaloid morphology with an exclusive or predominant epithelial cell population associated with decreased myoepithelial differentiation, while demonstrating MYB protein overexpression similar to the more common type of ACC. Strong and diffuse MYB expression by immunochemistry was observed in 14/17 (82%) of solid ACCs while MYB rearrangements were detected by break apart fluorescence in situ hybridization (FISH) in only 3/16 (19%) of solid ACCs. Conversely, weak MYB immunohistochemical expression was observed in only 7/204 (3%) of TNBC. Solid ACCs displayed a transcriptomic profile distinct from conventional ACCs with 549 genes showing a highly significant differential expression between conventional and solid ACC [false discovery rate (FDR) < 0.01; log2FC > |1|]. EnrichR and Kegg Pathway analyses identified PI3K-Akt and focal adhesion signaling pathways as significantly overexpressed in conventional ACCs compared with solid ACCs which significantly overexpressed the nitrogen metabolism pathway. CREBBP mutations and NOTCH activating gene mutations were only present in solid ACCs, concerning 5/16 (31%) of cases for each gene. Tumors with NOTCH activating mutations displayed a strong diffuse nuclear NICD1 staining, an established marker of Notch pathway activation. Solid ACCs also differed from basal-type TNBC, with fewer TP53 mutations and a more stable genomic profile on array comparative genomic hybridization (CGH). In summary, solid-type ACC of the breast is a distinct molecular entity within the ACC family and is different from common basal-type TNBC. MYB is a diagnostically useful biomarker of solid ACC and NOTCH could be a novel potential therapeutic target in 30% of cases.

Tall cell carcinoma of the breast with reversed polarity (TCCRP) with mutations in the IDH2 and PIK3CA genes: a case report

Tall cell carcinoma with reversed polarity (TCCRP) is a rare breast carcinoma with low malignant potential, initially named "breast tumor resembling the tall cell variant of papillary thyroid carcinoma", which has recently been recognized as a separate entity in the 5th edition of the WHO (World Health Organization) classification of breast tumors. Since the first report of this entity in 2003, more than 40 cases have been reported in the literature. Here, we report another case of this rare tumor in a 60-year-old woman. We performed immunohistochemical analyses and next-generation-sequencing (NGS) using the Oncomine™ Comprehensive DNA Panel (Thermo Fisher Scientific). The tumor showed the typical morphological features of TCCRP and a "triple-negative" phenotype. Moreover, we identified pathogenic mutations in the IDH2 (p.R172G) and PIK3CA (p.H1047R) genes. We report a case of TCCRP of the breast showing the characteristic morphologic, immunohistochemical and molecular features of this entity. There is still a limited number of cases with comprehensive molecular analyses reported in the literature. Therefore, we herewith contribute to a better understanding of the morphological and molecular characteristics as well as the clinical behavior of this rare entity.

Genotype-phenotype associations in breast pathology: Achievements of the past quarter century

The first genotype-phenotype relationship in breast pathology developed in 1994 with the discovery of the CDH1 gene. This finding eventually provided biological insight into the characteristic morphology of invasive lobular carcinoma. Subsequent investigative efforts have uncovered additional molecular alterations largely responsible for the histology of several breast neoplasms including secretory carcinoma, adenoid cystic carcinoma, tall cell carcinoma with reversed polarity, fibroepithelial lesions, and most recently, adenomyoepithelioma. Evaluation of the genomic landscape of other special types of breast cancer with distinctive growth patterns, such as invasive mucinous carcinoma, have yet to uncover recurring cytogenetic and/or molecular alterations. Despite the lack of a hallmark alteration in mucinous carcinoma, it is important to note the relative decrease in PIK3CA mutations compared with invasive carcinoma of no special type. In this review, we describe the clinical and pathologic features of breast tumors with recognized genotype-phenotype correlations and summarize the molecular alterations of mucinous carcinoma.

Papillary Renal Neoplasm With Reverse Polarity: A Morphologic, Immunohistochemical, and Molecular Study

We evaluated the clinicopathologic and chromosomal characteristics of a distinct subset of papillary renal tumors and compared them to a control series of papillary renal cell carcinoma types 1 and 2. Of the 18 patients, 9 were women and 9 were men, ranging in age from 46 to 80 years (mean, 64 y; median, 66 y). The tumors ranged in diameter from 0.6 to 3 cm (mean, 1.63 cm; median, 1.4 cm). Fourteen tumors were WHO/ISUP grade 2 and 4 were grade 1. All were stage category pT1. The tumors had branching papillae with thin fibrovascular cores, covered by cuboidal to columnar cells with granular eosinophilic cytoplasm, smooth luminal borders, and mostly regular and apically located nuclei with occasional nuclear clearing and inconspicuous nucleoli. Tubule formation and clear cytoplasmic vacuoles were observed in 5 and 9 tumors, respectively. Ten tumors had pseudocapsules. Psammoma bodies, necrosis, mitotic figures and intracellular hemosiderin are absent from all tumors. In contrast, papillary renal cell carcinoma type 1 consisted of delicate papillae covered by a single layer of cells with scanty pale cytoplasm with nuclei generally located in a single layer on the basement membrane of the papillary cores, while type 2 tumors had broad papillae covered by pseudostratified cells with eosinophilic cytoplasm and more randomly located nuclei. Both had occasional psammoma bodies, foamy macrophages and intracellular hemosiderin. Immunohistochemically, all were positive for pancytokeratin AE1/AE3, epithelial membrane antigen, MUC1, CD10, GATA3, and L1CAM. Cytokeratin 7 was positive in 16 tumors (1 had <5% positivity). CD117 and vimentin were always negative. α-methylacyl-CoA-racemase (AMACR/p504s) showed variable staining (range, 10% to 80%) in 5 tumors. However, all tumors in the control group were negative for GATA3 and positive for AMACR/p504s and vimentin immunostains. Fluorescence in situ hybridization analysis of the study group demonstrated chromosome 7 trisomy in 5 tumors (33%), trisomy 17 in 5 tumors (33%), and trisomy 7 and 17 in 3 tumors (20%). Chromosome Y deletion was found in 1 of 7 male patients and chromosome 3p was present in all tumors. No tumor recurrence or metastasis occurred. In summary, we propose the term papillary renal neoplasm with reverse polarity for this entity.

Invasive breast cancer: Current perspectives and emerging views

Invasive breast cancer constitutes a heterogeneous group of tumors. They comprise various histological types that differ in clinical presentation, imaging features, histopathological characteristics, biomarker profiles, prognostic and predictive parameters. The current classification of invasive breast cancer is based primarily on histopathological features. Invasive carcinoma of no special type accounts for the majority, with some rare entities also being described. With recent research and advances, there are emerging concepts, including new genetic insights of invasive breast cancer and the role of the stromal microenvironment. With greater understanding of the pathogenesis of invasive breast cancer, changes based on the correlation of histologic and genetic findings have been incorporated in the latest World Health Organization classification of breast tumors. Medullary carcinomas are subsumed as invasive carcinoma of no special type with basal-like and medullary features, regarded as part of the spectrum of tumor infiltrating lymphocyte-rich breast cancers. Tall cell carcinoma with reversed polarity is proposed as a distinct entity in recognition of unique IDH2 mutations. This article reviews conventional prognostic parameters, new histological entities, and updates on breast cancer classification, with inclusion of some genetic insights into breast cancer and the role of tumor infiltrating lymphocytes.

Recent advances in breast cancer research impacting clinical diagnostic practice

During the last decade, the genomics revolution has driven critical advances in molecular oncology and pathology, and a deeper appreciation of heterogeneity that is beginning to reshape our thinking around diagnostic classification. Recent developments have seen existing classification systems modified and improved where possible, gene-based diagnostics implemented and tumour-immune interactions modulated. We present a detailed discussion of this progress, including advances in the understanding of breast tumour classification, e.g. mixed ductal-lobular tumours and the spectrum of triple-negative breast cancer. The latest information on clinical trials and the implementation of gene-based diagnostics, including MammaPrint and Oncotype Dx and others, is synthesised, and emerging targeted therapies, as well as the burgeoning immuno-oncology field, and their relevance in breast cancer, are discussed. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.