Overdiagnosis of breast malignancy: Azzopardi's Problems in Breast Pathology revisited, Part I

Dr. John G. Azzopardi's textbook Problems in Breast Pathology is a critical work for breast pathologists. His observations on over- and underdiagnosis of breast malignancy are summarized in two chapters which are highly educational for everyday practice to reach an accurate diagnosis. Almost five decades later, his observations are still valid, and the same problems persist. In two separate reviews, we revisit these chapters and discuss these diagnostic challenges with an updated perspective and include developments (most importantly immunohistochemistry) in the field since then. In part I, lesions which may be overdiagnosed as malignancy are discussed, including those that were covered in Dr. Azzopardi's textbook (mainly sclerosing adenosis and radial scar) and some others that exert challenges on the pathologist. In part II, we will cover underdiagnosis of breast malignancy.

Atypia in breast pathology: what pathologists need to know

Despite the importance of atypia in diagnosing and classifying breast lesions, the definition of atypia varies depending on the context, with a lack of consistent and objective criteria for assessment. Atypia in breast pathology may be cytonuclear and/or architectural with different applications and implications. Cytonuclear atypia is used to assist the distinction of various intraductal epithelial proliferative lesions including usual ductal hyperplasia (UDH) versus atypical ductal hyperplasia (ADH) or ductal carcinoma in situ (DCIS), and to grade DCIS. In invasive carcinoma, nuclear atypia (i.e., nuclear pleomorphism) is a component of the histological grading system. Stromal cell cytonuclear atypia is one of the key features used to distinguish fibroadenoma from phyllodes tumour (PT) and to classify PT as benign, borderline or malignant. Similarly, cytonuclear atypia is used in the evaluation of myoepithelial cell alterations in the breast. Architectural atypia is used to differentiate flat epithelial atypia (FEA) from ADH or DCIS. In addition to the inherent subjectivity in the interpretation of atypia, which presents as a morphological continuum reflecting a biological spectrum, the lack of standardisation in defining atypia augments diagnostic discordance in breast pathology, with potential implications for patient management. Evidence to date suggests that the traditional criteria used to assess atypia may require modification in the era of digital pathology primary diagnosis. This review aims to provide a comprehensive review of atypia in breast pathology with reference to inconsistencies, challenges and limitations.

Apocrine lesions of the breast

Apocrine change is recognised in benign, atypical and malignant lesions of the breast. Apocrine metaplasia, a frequent finding in the breast of women over the age of 25 years, is most commonly seen in benign cysts with a simple or papillary configuration. Apocrine change is also recognised in other benign lesions including sclerosing adenosis, now known as apocrine adenosis. Apocrine atypia usually refers to cytological atypia in which there is at least threefold variation in nuclear size but architectural atypia may also occur. The distinction between atypical apocrine hyperplasia and non-high-grade apocrine ductal carcinoma in situ may be difficult due to the relative rarity of these entities and the lack of validated diagnostic criteria. Lobular carcinoma in situ (LCIS) with apocrine change is considered to be a variant of pleomorphic LCIS. An apocrine variant of encapsulated papillary carcinoma is also recognised. Apocrine change is described in invasive carcinoma, including no special type, lobular, micropapillary and mucinous variants. The recent WHO 2019 update recognises 'carcinoma with apocrine differentiation' as a special type breast carcinoma based on the presence of apocrine morphology in at least 90% of the tumour. Tumours with apocrine morphology are usually but not always hormone receptor negative. Human epidermal growth factor receptor 2 (HER-2) status is variable. Molecular studies have identified breast tumours with apocrine features and high expression of androgen receptor mRNA including 'luminal androgen receptor tumours' and 'molecular apocrine tumours'. The term 'pure apocrine carcinoma' has been proposed to describe an invasive carcinoma with apocrine morphology that is oestrogen and progesterone receptor negative and androgen receptor positive. HER-2 status may be positive or negative. This article reviews the pathology of benign, atypical and malignant apocrine lesions of the breast, with emphasis on diagnostic criteria including an approach to evaluation of apocrine lesions on needle core biopsy, and recent advances in our understanding of invasive apocrine carcinoma.

Mixed Invasive Apocrine Papillary/Micropapillary Carcinoma of the Breast: Another Brick in the Triple-Negative Wall

Pure invasive papillary carcinoma (IPC) is a rare subtype of breast carcinoma with good prognosis compared with classical invasive breast carcinoma (IBC) of no special type. The majority of IPC are estrogen receptor and progesterone receptor (ER/PR) positive and HER2 negative (luminal A-like). We report the case of a 72-year-old women who was referred to the Senology Clinic for a routine workup following surgery for an intraductal papilloma. The core needle biopsy (CNB) showed a lesion mainly composed of irregular papillae and micropapillae with apocrine epithelial cells of low-to-intermediate nuclear grade, without a myoepithelial cell layer within the papillae and at the periphery, as demonstrated with multiple immunostains. The diagnosis of apocrine papillary lesion of uncertain malignant potential was made. The subsequent lumpectomy showed an IBC with the same cyto-architectural features as the CNB. In addition, lymphovascular invasion and papillary/micropapillary apocrine in situ lesion were noted. Notably, the tumor was ER/PR and HER2 negative and strongly positive for androgen receptor. A final diagnosis of mixed apocrine papillary/micropapillary carcinoma with triple-negative status was made. To the best of our knowledge, this is the first report of an IBC with these features. Breast pathologists should be aware of this entity when dealing with CNB samples characterized by a complex papillary lesion with apocrine atypia that lacks a myoepithelial cell layer on multiple immunostains. These lesions should be classified at least as of uncertain malignant potential based on the cyto-architectural features prompting a surgery for removal.

Ultrasound Features and Rate of Upgrade to Malignancy in Atypical Apocrine Lesions of the Breast

OBJECTIVES

To evaluate the ultrasound (US) features and rate of upgrade to malignancy in atypical apocrine lesions (AALs) of the breast, diagnosed on percutaneous needle biopsy.

METHODS

This retrospective study included 17 AALs diagnosed by needle biopsy in 15 patients. For 16 of the 17 AALs, subsequent surgical excision (n = 14) or 8-gauge vacuum-assisted biopsy (n = 2) was performed. Ultrasound features were retrospectively analyzed according to the American College of Radiology Breast Imaging Reporting and Data System lexicon.

RESULTS

Of 17 AALs, 13 (76.5%) were atypical apocrine hyperplasia; 3 (17.6%) were atypical apocrine adenosis; and 1 (5.9%) was combined atypical apocrine hyperplasia and atypical apocrine adenosis on needle biopsy. Subsequently, 4 of 16 AALs (25%) were upgraded to malignancy at surgical excision. On US imaging, all 17 lesions presented as masses, which were mainly irregular and noncircumscribed (n = 8) or oval/round and noncircumscribed (n = 7) with isoechogenicity or hypoechogenicity. Rarely, an AAL would show complex cystic and solid echogenicity (n = 1) or appear as a hypoechoic mass with oval shape and a circumscribed margin (n = 1).

CONCLUSIONS

Atypical apocrine lesions of the breast often showed suspicious malignant features on US imaging. Given the high upgrade rate (25%), the diagnosis of an AAL by needle biopsy warrants subsequent surgical excision.

[Histological lesions of risk of breast carcinoma. Survival guide for the general pathologist]

Proliferative epithelial lesions are risk factors for breast cancer. They are a heterogeneous group of lesions in which the presence of atypia is related to varying degrees of risk. They should be considered in the differential diagnosis with benign lesions, in situ ductal carcinoma and infiltrating carcinoma. An accurate histopathological diagnosis is important in choosing the best therapeutic option, including vacuum assisted biopsy and surgery. We revise diagnostic criteria and the differential diagnosis of usual ductal hyperplasia, radial scar and complex sclerosing lesions, distinct types of adenosis, papillary lesions, atypical ductal hyperplasia, flat epithelial atypia and lobular neoplasia in situ. Furthermore, we summarize the degree of risk associated with the different conditions and management possibilities.

Breast Atypical Apocrine Adenosis: A Case Report and Literature Review

Atypical apocrine adenosis (AAA) is a benign lesion of the breast that is identified more frequently today than in the past when it was considered a rare diagnosis and commonly misdiagnosed as other malignant lesions of the breast. AAA is defined as the presence of apocrine cytology in a recognisable lobular unit associated with sclerosing adenosis. We present a case of an incidental finding of AAA and discuss diagnostic challenges and their implications on clinical management.

The diagnostic utility of EZH2 H-score and Ki-67 index in non-invasive breast apocrine lesions

In diagnostic breast pathology, there is no reliable applicable immunostain to help discern atypical and in situ apocrine lesions from benign apocrine tissue. At present, the diagnosis of non-invasive apocrine lesions remains challenging with current diagnoses rendered based on discrete morphologic characteristics on conventional hematoxylin and eosin staining. Interobserver variability is significant even among subspecialists partly due to lack of adjuvant diagnostic immunohistochemical stains. Herein, we set to elucidate the potential utility of EZH2 and Ki-67 immunostains as tangible tools in non-invasive apocrine proliferations. A cohort of apocrine breast lesions [Benign apocrine hyperplasia (BAH), n = 10; Atypical apocrine hyperplasia (AAH), n = 16; Apocrine ductal carcinoma in situ (ADCIS), n = 12] were subjected to EZH2 immunostaining and analyzed via H-scoring of nuclear expression. Mean H-scores for EZH2 progressively increased from BAH (23.5), to AAH (47.4) and ADCIS (196.4), and showed a significant difference utilizing the Kruskal-Wallis test (p < 0.0001). Further interrogation of Ki-67 demonstrated incremental expression from BAH to AAH and ADCIS at 1.6 %, 4.7 % and 24.7 %, respectively (p < 0.0001, Kruskal-Wallis test), suggesting an association with increased proliferation. Our results demonstrate that a combination of EZH2 and Ki-67 immunostaining may be employed in differentiating among challenging apocrine breast lesions and suggest a putative diagnostic utility for EZH2 and Ki-67 in non-invasive apocrine breast lesions.

Pitfalls and controversies in pathology impacting breast cancer management

Introduction: Breast cancer is a heterogeneous disease, at morphological, molecular, and clinical levels and this has significant implications for the diagnosis and management of the disease. The introduction of breast screening, and the use of small tissue sampling for diagnosis, the recognition of new morphological and molecular subtypes, and the increasing use of neoadjuvant therapies have created challenges in pathological diagnosis and classification.Areas covered: Areas of potential difficulty include columnar cell lesions, particularly flat epithelial atypia, atypical ductal hyperplasia, lobular neoplasia and its variants, and a range of papillary lesions. Fibroepithelial, sclerosing, mucinous, and apocrine lesions are also considered. Established and newer prognostic and predictive markers, such as immune infiltrates, PD-1 and PD-L1 and gene expression assays are evaluated. The unique challenges of pathology assessment post-neoadjuvant systemic therapy are also explored.Expert opinion: Controversies in clinical management arise due to incomplete and sometimes conflicting data on clinicopathological associations, prognosis, and outcome. The review will address some of these challenges.

Core needle biopsy of benign, borderline and in-situ problematic lesions of the breast: Diagnosis, differential diagnosis and immunohistochemistry

Core needle biopsy (CNB) is the most common sampling technique for the histologic evaluation of breast abnormalities. Diagnosing benign proliferative, borderline and some in-situ lesions in CNB is challenging and subject to a significant degree of interobserver variability. In addition, due to the inherent limitations of CNB, "upgrading" to a more significant pathology at excision is an important consideration for some lesions. Pathologists carry a major responsibility in patient diagnosis, risk stratification and management. Familiarity with the histologic features and the clinical significance of these common and problematic lesions encountered in CNB is necessary for adequate treatment and patient follow-up. This review will focus on benign, atypical and in-situ epithelial proliferations, papillary lesions, radial sclerosing lesions, adenosis and cellular fibroepithelial lesions. Highlights of histologic features, useful strategies for accurate diagnosis, basic immunohistochemistry and management will be presented.

Suppression of OSCC malignancy by oral glands derived-PIP identified by iTRAQ combined with 2D LC-MS/MS

Oral squamous cell carcinoma (OSCC) is the most common malignancy in head and neck cancer and a global cause of cancer-related death. Due to the poor survival rates associated with OSCC, there is a growing need to develop novel technologies and predictive biomarkers to improve disease diagnosis. The identification of new cellular targets in OSCC tumors will benefit such developments. In this study, isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics analysis combined with 2-dimensional liquid chromatography and tandem mass spectrometry (2D LC-MS/MS) were used to identify differentially expressed proteins (DEPs) between tumor and normal tissues. Of the DEPs detected, the most significantly downregulated protein in OSCC tissue was prolactin-inducible protein (PIP). Clonogenic and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) experiments showed that the proliferation capacity of OSCC cells overexpressing PIP decreased due to cell cycle arrest at the G0/G1 checkpoint. Wound-healing and transwell assay further showed that PIP overexpression also reduced the migration and invasion of OSCC cells. Immunohistochemistry (IHC) was used to analyze the expression in OSCC, indicating that PIP may be secreted by glandular cells and have an inhibitory effect on OSCC cells to produce. In western blot analysis, silencing studies confirmed that PIP mediates these effects through the AKT/mitogen-activated protein kinase (MAPK) signaling axis in OSCC cells. Taken together, this study reveals PIP as a key mediator of OSCC cell growth, migration, and invasion through its effect on AKT/MAPK signaling.

Apocrine lesions of the breast: part 2 of a two-part review. Invasive apocrine carcinoma, the molecular apocrine signature and utility of immunohistochemistry in the diagnosis of apocrine lesions of the breast

Pure apocrine carcinoma of the breast is rare and has been defined by using a combination of morphologic (apocrine morphology in >90% of tumour cells) and immunohistochemical criteria (oestrogen receptor (ER) and progesterone receptor (PR) negative and androgen receptor (AR) positive). Recent advances in the molecular classification of breast tumours have uncovered a subset of breast tumours associated with high expression of androgen receptor mRNA including the so-called 'luminal androgen receptor (LAR) tumours' and 'molecular apocrine tumours' (MATs). Recognition of these tumour subsets has opened potential avenues for therapies exploiting the AR pathway in triple negative breast carcinoma (TNBC). In this second part of our two-part review, we focus on the definition of pure apocrine carcinoma, recent advances in understanding the molecular apocrine signature in breast carcinoma, its relationship to pure apocrine carcinoma defined at the level of light microscopy and immunohistochemistry (IHC) and the therapeutic implications of androgen expression in TNBC. We complete the article with a summary of the utility of IHC in stratifying apocrine lesions of the breast.

Apocrine lesions of the breast: part 1 of a two-part review: benign, atypical and in situ apocrine proliferations of the breast

Apocrine morphology is a common phenomenon encountered in everyday breast pathology practice, and is defined as cuboidal or columnar cells exhibiting abundant eosinophilic granular cytoplasm, prominent apical granules, a low nuclear-cytoplasmic ratio, and round nuclei with pale chromatin and prominent nucleoli. Apocrine morphology is recognised in benign, atypical and malignant lesions of the breast. The morphology of apocrine atypia and non-high-grade apocrine ductal carcinoma in situ (DCIS) is less well defined due to the relative rarity of these lesions. In part 1 of this two-part review, we focus on the morphological characteristics of benign, atypical and in situ apocrine lesions of the breast, summarise the available data to date regarding distinction of atypical apocrine proliferations from non-high-grade apocrine DCIS and the biological significance of apocrine atypia, and provide practical guidance on handling these difficult lesions. Part 2 of this review will focus on the concept of pure apocrine carcinoma with emphasis on its definition and molecular data, including the current understanding of the molecular apocrine signature in breast carcinoma. We complete the review with a synopsis on the utility of immunohistochemistry in the diagnosis of apocrine lesions of the breast.

Atypical Ductal Lesions of the Breast: Criteria, Significance, and Laboratory Updates

Context.—

Atypical ductal hyperplasia (ADH) is a challenging diagnosis defined by cytologic and architectural features that carries an increased risk of subsequent carcinoma when diagnosed in isolation. In addition, ADH may secondarily involve benign breast lesions, wherein it carries variable clinical significance.

Objectives.—

To review the diagnostic criteria and clinical significance of ADH in isolation and as it involves benign breast lesions, and to review the evolving literature on its molecular signature.

Data Sources.—

Recently published studies that collectively examine ADH were reviewed.

Conclusions.—

Atypical ductal hyperplasia carries an increased risk of subsequent carcinoma in isolation and when it involves most benign breast lesions. Identifying which cases of ADH will be upgraded to carcinoma has been challenging, and new laboratory developments, such as EZH2 overexpression, may have a future role.