Myoepithelial cell staining patterns of papillary breast lesions: from intraductal papillomas to invasive papillary carcinomas

Encapsulated papillary carcinoma of the breast clinicopathological features and management: Could sentinel lymph node biopsy be exempted?

BACKGROUND

Papillary lesions in the breast pose diagnostic and therapeutic challenges. Encapsulated papillary carcinoma (EPC) is a rare breast cancer. However, evidence-based guidelines are limited. For this reason, there is no complete clarity in diagnosis and treatment management, and there are insufficient studies in the literature. This study aimed to examine the necessity of sentinel lymph node sampling in the management of EPC, in line with patients' clinicopathological data.

METHODS

We retrospectively screened patients with EPC in our clinic between January 2012 and March 2022. We recorded and statistically evaluated patients' demographic, clinical, radiological, pathological, and treatment management.

RESULTS

Sixty-four patients with EPCs were identified. The final pathologic evaluation revealed that 19 patients (18.7%) had pure EPC, 27 patients (43.7%) had EPC with associated ductal carcinoma in situ and 18 patients (37.5%) had EPC associated with invasion. The mean age was 61 years, and two patients were male. Breast-conserving surgery was performed in 62 patients, and simple mastectomy was performed in two patients. Sentinel lymph node biopsy (SLNB) was positive in only one patient. Sixty-three patients with EPC were hormone receptor-positive, and one patient was triple-negative and was associated with invasion. None of the patients died, one had a local recurrence, and a mastectomy was performed.

CONCLUSIONS

The overall prognosis and long-term survival of patients with EPC were excellent. Our study and the current literature indicate that routine SLNB is overtreatment because surgical excision with negative margins is sufficient in EPC cases and lymph node metastasis is rare, even with an invasive component.

Pitfalls in breast pathology

Accurate pathological diagnosis is the cornerstone of optimal clinical management for patients with breast disease. As non-operative diagnosis has now become the standard of care, histopathologists encounter the daily challenge of making definitive diagnoses on limited breast core needle biopsy (CNB) material. CNB samples are carefully evaluated using microscopic examination of haematoxylin and eosin (H&E)-stained slides and supportive immunohistochemistry (IHC), providing the necessary information to inform the next steps in the patient care pathway. Some entities may be difficult to distinguish on small tissue samples, and if there is uncertainty a diagnostic excision biopsy should be recommended. This review discusses (1) benign breast lesions that may mimic malignancy, (2) malignant conditions that may be misinterpreted as benign, (3) malignant conditions that may be incorrectly diagnosed as primary breast carcinoma, and (4) some IHC pitfalls. The aim of the review is to raise awareness of potential pitfalls in the interpretation of breast lesions that may lead to underdiagnosis, overdiagnosis, or incorrect classification of malignancy with potential adverse outcomes for individual patients.

Contrast-enhanced ultrasound combined with ultrasonic elastography to diagnose encapsulated papillary carcinoma: A case report

Encapsulated papillary carcinoma is a rare malignant breast tumor with low malignancy, and is most commonly found in postmenopausal women. On ultrasound, encapsulated papillary carcinoma has an envelope, and anechoic areas inside the lesion. Contrast-enhanced ultrasound shows marked enhancement without size expand, and ultrasonic elastography suggests soft parenchyma in the lesion. However, it is often challenging to differentiate between encapsulated papillary carcinoma and other breast tumors, especially some benign lesions. Here, we reported a case of encapsulated papillary carcinoma in a 65-year-old female patient who discovered a breast mass three years ago and presented with nipple discharge and pain six months before. This case report demonstrated the ability of multimodal ultrasound to diagnose encapsulated papillary carcinoma.

Canine and feline in situ mammary carcinoma: A comparative review

Carcinoma in situ of the breast is a well-known entity in humans. In veterinary medicine, particularly in canine and feline mammary literature, there is no agreement whether the term in situ should be used to indicate a specific carcinoma histotype or the noninvasive status of a carcinoma of any histotype. Moreover, in the most recent histologic classification of mammary tumors published by the Davis-Thompson Foundation, it is suggested to abandon the term carcinoma in situ given the lack of standardized criteria defining this entity, replacing it with epitheliosis or ductal/lobular hyperplasia with severe atypia. This publication presents a critical review of the term in situ in human and veterinary medicine considering the evolution of the term over the years and its heterogeneous use by different authors, including variations in immunohistochemical markers for classification. This review aims to point out the lack of uniformity in the nomenclature and classification issues in veterinary medicine regarding the use of the term in situ, laying the ground for a process of standardization in future publications.

Avoiding "False Positive" and "False Negative" Immunohistochemical Results in Breast Pathology

Immunohistochemistry (IHC) plays an important role in the evaluation of breast pathology specimens to provide both diagnostic and prognostic/therapeutic information. Although most IHCs used in breast pathology can be easily interpreted, pitfalls do exist, especially in some uncommon scenarios. This review intends to focus on the challenging areas such as the interpretation of myoepithelial cell markers in differentiating benign proliferation and in situ carcinoma from invasive carcinoma, lobular cell markers in differentiating lobular from ductal carcinoma, cytokeratin and other markers in diagnosing metaplastic carcinoma, and breast tissue origin markers in diagnosing breast primary carcinoma. The challenges in interpreting prognostic and predictive markers will be also discussed.

Papillary Breast Tumors: Continuing Controversies and Commentary on WHO's 2019 Criteria and Classification

The category of papillary breast tumors includes a limited number of entities. Nonetheless, this relatively uncommon group of tumors seems to instigate a disproportionate degree of diagnostic disquiet. As a group, papillary breast tumors suffer from a relatively high rate of discordant interpretation. The latter is due to the inherent complexity of the lesions compounded by conflicting criteria as well as simmering controversies. For instance, "encapsulated" papillary carcinoma remains contentious with regards to whether these are noninvasive or not, and the assessment of the extent of the invasive versus noninvasive components in many solid papillary carcinomas can be problematic. The latest classification system of breast tumors enunciated by the World Health Organization (WHO), that is, Breast Tumors, which appeared in 2019, mainly sought to incorporate advances in basic and clinical sciences into diagnostic criteria for the entire spectrum of breast neoplasms-including papillary ones. The latter category of tumors is discussed at some length in Breast Tumors; however, it still appears to suffer from some lack of clarity in its subclassification. It is our intent in this communication to provide an overview of the controversies around papillary breast tumors, and offer comments on its coverage in Breast Tumors-so that any tangible or perceived ambiguities therein could be addressed in its next edition.

Solid Papillary Carcinoma and Encapsulated Papillary Carcinoma of the Breast: Clinical-Pathologic Features and Basement Membrane Studies of 50 Cases

INTRODUCTION

Solid papillary carcinoma (SPC) and encapsulated papillary carcinoma (EPC) of the breast are usually considered in situ lesions due to favorable prognosis, despite the variable presence of myoepithelial cells. We aimed to describe clinical-pathologic features including basement membrane (BM) studies in these tumors.

METHODS

Patients diagnosed with SPC and EPC in 2000-2019 were retrospectively identified. Microscopic slides and clinical history were reviewed. Immunohistochemical stains for BM and myoepithelial markers were performed.

RESULTS

Of 23 SPCs and 27 EPCs, there were 5/23 (21.7%) pure SPCs and 9/27 (33.3%) pure EPCs, while 4/23 (17.4%) and 12/27 (44.5%) were associated with ductal carcinoma in situ (DCIS), and 6/23 (26.1%) and 6/27 (22.2%) with invasive carcinoma, respectively; 8/23 (34.8%) SPCs were considered invasive. The median tumor size was 1.7 cm (range 0.1-16). All tumors were positive for hormone receptors and negative for HER2. Myoepithelial cells were absent in 20 tumors (40%) and focally present in 30 (60%). Collagen IV and laminin were negative in most invasive lesions, but they were expressed in 21/21 (100%) and 18/21 (85.7%) of EPCs without invasion, and 16/17 (94.1%) and 10/17 (58.8%) SPCs, including invasive SPCs, respectively. Lymph node involvement was identified in 3/26 (11.5%) patients, including micrometastasis in 1 EPC associated with DCIS, macrometastasis in 1 EPC associated with invasive carcinoma, and isolated tumor cells in 1 invasive SPC. Of 31 patients with outcome data (median follow-up 35 months, range 1-85), 2 (6.5%; 1 SPC, 1 EPC) developed local recurrence, both associated with invasive carcinoma. No distant recurrences or deaths were observed.

CONCLUSIONS

Our study confirms favorable prognosis of SPCs and EPCs, with 2 local recurrences occurring in the presence of invasion. SPCs are more commonly associated with invasive carcinoma or considered invasive compared to EPCs (60.9 vs. 22.2%). The presence of BM material and lack of lymph node involvement in most cases indicates that the majority of these tumors may represent in situ lesions; however, some may behave as low-grade invasive malignancy with metastatic potential even in the absence of conventional invasion.

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.

Intracystic papillary carcinoma of the male breast: Dilemmas in diagnosis and management

Intracystic papillary carcinoma (IPC) is a rare malignancy of the breast which is usually found in postmenopausal women. It is still rarer in males and may present with signs of a benign cystic lump. It is sub-classified into three equally prevalent groups considering treatment strategies: intracystic papillary carcinoma alone, intracystic papillary carcinoma with ductal carcinoma in-situ, and those with evidence of invasion. Even if a preoperative diagnosis is achieved, there are no specific guidelines for the treatment of IPC. Treatment modalities including the extent of surgical excision, lymph node dissection, radiation, and chemotherapy are determined by the grade and size of the lesion and sub-types. However, several reports and studies showed good prognosis with conservative surgery without axillary dissection in IPC not associated with carcinoma in situ or micro-invasion. We present a 40 years old male patient with IPC who was managed by modified radical mastectomy and adjuvant hormone therapy. A brief review of the literature and clinical characteristics, pathology, and treatment of IPC are discussed.

Next-generation sequencing revealed recurrent ZFPM1 mutations in encapsulated papillary carcinoma of the breast

Encapsulated papillary carcinoma (EPC) of the breast is a rare subtype of tumor. To date, the genetic abnormalities underlying EPC remain elusive. The purpose of this study was to gain further insight into EPC mutation profile. Forty-one EPCs diagnosed from 2015 to 2018 were included. Twenty-six EPCs were submitted to whole-exome sequencing (WES), and a 185 gene-targeted sequencing panel was designed to validate the results of the 26 EPCs that underwent WES and 15 additional cases. Recurrently mutated genes were further confirmed by Sanger sequencing. Our study revealed multiple recurrently mutated genes including PI3K-AKT-mTOR pathway genes (PIK3CA, AKT1, ULK1, MAP3K1, MAP2K4, RHOA, and PTEN) (27/41, 65.8%) and chromatin modification genes (ZFPM1, GATA3, CTCF, and KMT2C) (21/41, 51.2%) in EPC. Importantly, somatic ZFPM1 mutations existed in 9/41 (21.9%) of the EPCs. The frequency of ZFPM1 mutations in the EPCs was significantly higher than that of other tumor types. Of the nine ZFPM1 mutations, seven were frameshift mutations, and the remaining two were nonsense mutations. Moreover, a significant concurrence of ZFPM1 and PI3K-AKT-mTOR mutations were revealed in the EPCs. Of note, no TP53 mutations were detected in our EPCs, whereas it was detected in a considerable proportion of the luminal A invasive ductal carcinomas of no special type (IDC-NSTs) from TCGA. We reveal that recurrent somatic ZFPM1 mutation is characteristic of EPC and concurred with mutations in the PI3K-AKT-mTOR pathway. The distinctive genetic features of EPC might underlie its special histological structures and indolent behavior.

Molecular analysis of encapsulated papillary carcinoma of the breast with and without invasion

Encapsulated papillary carcinomas (EPCs) of the breast are a unique variant of papillary carcinoma confined to a cystic space with absent or attenuated myoepithelial cell layer. Although staged as an in situ lesion, it can be associated with invasive ductal carcinoma (IDC). We sought to compare the genomic characteristics of pure EPC and EPC with associated invasive carcinoma (EPCi) at the genomic level. All cases of EPCi harbored recurrent hotspot mutations in PIK3CA. PIK3CA, KMT2A, and CREBBP deleterious somatic events were found across both tumor groups, irrespective of invasion status. At the whole transcriptomic level, EPCi cases displayed remarkably similar mRNA profiles when compared to EPC. When EPCi cases were compared with their corresponding IDC, despite significant overlap, we identified differential gene expression in 39 genes with enrichment of multiple pathways including extracellular matrix regulation, cell adhesion, and collagen fibril organization. Despite morphologic, genotypic, and transcriptomic overlap between pure EPC and EPCi, the latter tumors are likely advanced lesions with PIK3CA activating mutations and enrichment of stromal-related genes implicated in the switch to IDC.

Characterization of neoplastic cells outlining the cystic space of invasive micropapillary carcinoma of the canine mammary gland

BACKGROUND

Invasive micropapillary carcinoma (IMPC) is a rare malignant breast tumor and a variant form of invasive ductal carcinoma that is an aggressive neoplasm of the human breast and canine mammary gland. The importance of the tumor microenvironment in cancer development has gradually been recognized, but little is known about the cell types outlining the cystic space of canine IMPC. This study aimed to characterize the neoplastic cells outlining the cystic space of IMPC.

RESULTS

Immunohistochemistry (IHC), immunofluorescence (IF), superresolution and transmission electron microscopy (TEM) were used to assess the cell types in the cystic areas of IMPCs. Cells expressing the mesenchymal markers alpha-smooth muscle actin (αSMA), Vimentin, and S100A4 outlined the cystic space of IMPC. Furthermore, loss of epithelial cell polarity in IMPC was shown by the localization of MUC1 at the stroma-facing surface. This protein modulates lumen formation and inhibits the cell-stroma interaction. Immunohistochemical and IF staining for the myoepithelial cell marker p63 were negative in IMPC samples. Furthermore, associated with peculiar morphology, such as thin cytoplasmic extensions outlining cystic spaces, was observed under TEM. These observations suggested cells with characteristics of myoepithelial-like cells.

CONCLUSIONS

The cells outlining the cystic space of IMPC in the canine mammary gland were characterized using IHC, IF and TEM. The presence of cells expressing αSMA, Vimentin, and S100A4 in the IMPC stroma suggested a role for tumor-associated fibroblasts in the IMPC microenvironment. The reversal of cell polarity revealed by the limited basal localization of MUC1 may be an important factor contributing to the invasiveness of IMPC. For the first time, the cystic space of canine mammary gland IMPC was shown to be delimited by myoepithelial-like cells that had lost p63 expression. These findings may enhance our understanding of the cellular microenvironment of invasive tumors to improve cancer diagnosis and treatment.

Pathology of breast papillary neoplasms: Community hospital experience

In this study, 550 breast papillary neoplasms collected in a community hospital over more than ten years were reviewed and analyzed. This included 457 intraductal papillomas, 53 papillary carcinomas, 35 papillary DCIS and five invasive papillary carcinomas. The diagnostic rate of papillary neoplasms increased over time, likely due to better recognition by pathologists. Intraductal papillomas occurred most frequently in the upper outer quadrants and contained ADH/DCIS in 19% of cases. A total of 28% of non-incidental papillomas were associated with ADH/DCIS, and 29% of patients with papillomas had ADH/DCIS in adjacent tissue; nearly half of papillomas that were > 1 cm in size contained ADH/DCIS in the papilloma or adjacent to it. No single feature could predict an upgrade on excision for non-atypical intraductal papillomas diagnosed on core biopsy. There was no significant difference in the association of ADH/DCIS with central or peripheral papillomas. The overall upgrade rate of non-atypical intraductal papillomas to DCIS on excision was 2%, which justifies the conservative management of non-atypical sub-centimeter lesions. Papillary carcinomas occurred in older than intraductal papilloma patients and were most frequent in the upper quadrants. Although classically devoid of a myoepithelial cell layer, papillary carcinomas may contain some residual or even an ample myoepithelial cell layer in the papillae. An association between papillary carcinoma and conventional invasive carcinoma was found in 40% of EPCs and 89% of SPCs. Papillary DCIS was usually low- or intermediate-grade. The presence of a myoepithelial cell layer in the papillae was not inconsistent with this diagnosis. Invasive papillary carcinoma may have two histologic patterns: papillary and cribriform.

Immunohistochemistry for diagnosis and prognosis of breast cancer: a review

Breast cancer is the most prevalent malignant tumor and main oncologic cause of mortality in women. Although most diagnosis of breast pathology is accomplished using hematoxylin and eosin stained sections, some cases require immunohistochemistry for proper evaluation. We investigated the latter cases including distinctions between ductal and lobular carcinoma, in situ and invasive carcinoma, typical ductal hyperplasia and atypical ductal hyperplasia/ductal carcinoma in situ, papillary and spindle cell lesion assessment, metastasis evaluation, and assessment of prognostic and therapy markers. E-cadherin is used to differentiate ductal and lobular carcinoma; 34βE12, CK8, p120 catenin and β-catenin also produce consistent results. Myoepithelial cell (MEC) stains are used to evaluate in situ and invasive carcinoma; calponin, smooth muscle myosin heavy chain and p63 are sensitive/specific markers. 34βE12 and CK5/6 are positive in ductal hyperplasia, which enables its differentiation from atypical ductal hyperplasia and ductal carcinoma in situ. CK 5/6, ER and MEC markers are consistent options for evaluating papillary lesions. Spindle cell lesions can be assessed using β-catenin, SMA, CD34, p63, CKs and hormone receptors. It is important to differentiate primary carcinomas from metastases; the most commonly used markers to identify breast origin include mammaglobin, GCDFP-15, GATA3 and ER, although none of these is completely sensitive or specific. Immunohistochemistry can be used to evaluate central prognostic and predictive factors including molecular subtypes, HER2, hormone receptors, proliferation markers (Ki-67) and lymph-vascular invasion markers including ERG, CD31, CD34, factor VIII and podoplanin. Owing to the complexity of mammary lesions, diagnosis also depends on each particular situation, evaluation of cytological characteristics revealed by immunochemistry and correlation with histological findings.

Magnetic Resonance Imaging Features of Breast Encapsulated Papillary Carcinoma

OBJECTIVE

This study aimed to describe the magnetic resonance imaging (MRI) features of pure breast encapsulated papillary carcinoma (EPC).

MATERIALS AND METHODS

Ten patients with histopathologically confirmed breast pure EPC were reviewed. Two radiologists evaluated lesion MRI characteristics.

RESULTS

The EPC presented oval or round mass with circumscribed margin on MRI. In addition, 4 cases exhibited a cystic-solid mixed mass with mural nodules, and 4 cases exhibited a liquid level that indicated the possibility of hemorrhage.

CONCLUSIONS

A well-defined cystic-solid mixed mass with mural nodules, or a circumscribed mass exhibiting the possibility of hemorrhage, may suggest the diagnosis of EPC.

Encapsulated papillary carcinoma of the breast: A clinicopathological study of 49 cases

BACKGROUND

Encapsulated papillary carcinoma (EPC) has been considered as a variant of ductal carcinoma in situ. Recent studies suggest that EPC could be invasive, as it often lacks myoepithelial cells (MECs) at their periphery. The current study was performed to investigate the biological features of EPC.

METHODS

Forty-nine EPC patients admitted to the Tai׳an Central Hospital and Qilu Hospital of Shandong University from January 2004-December 2014 were included in this study. We retrospectively analyzed the clinicopathological findings, the presence and distribution of MECs, as well as the outcomes.

RESULTS

The mean age at diagnosis was 68.5 years. The mean tumor size was 2.0 cm. MECs were completely absent in all the 49 cases. Most tumors were estrogen receptor and progesterone receptor positive (95.9%). Human epidermal growth factor receptor 2 1+ immunoreactivity was seen in only 8 cases. Twenty-five patients underwent lumpectomy and 24 underwent mastectomy. Thirty-nine received evaluation of lymph node (LN), and 3 (7.7%) patients had LN involvement. Follow-up information was available in 29 patients (8-104 months, mean 47 months), among which 5 developed local recurrences and 2 distant metastases.

CONCLUSION

EPC is an indolent invasive carcinoma with biological features between in ductal carcinoma in situ and invasive carcinoma, with predominance of the latter. EPC rarely showed LN involvement and was characterized by favorable prognosis. EPC can be treated with adequate local therapy and hormonal therapy, whereas the benefit of radiation after lumpectomy remains uncertain.

Core Needle Biopsy of the Breast: An Evaluation of Contemporary Data

Benign and atypical lesions associated with breast cancer risk are often encountered in core needle biopsies (CNBs) of the breast. For these lesions, the rate of "upgrade" to carcinoma in excision specimens varies widely in the literature. Many CNB studies are limited by a lack of radiological-pathological correlation, consistent criteria for excision, and clinical follow-up for patients who forego excision. This article highlights contemporary diagnostic criteria and outcome data that would support an evidence-based approach to the management of these nonmalignant lesions of the breast diagnosed on CNB.

Update on Immunohistochemical Analysis in Breast Lesions

CONTEXT

- The utility of immunohistochemistry (IHC) in breast lesions needs to be updated with exceptions among these lesions. Biomarker studies with IHC in triple-negative breast carcinoma may help develop targeted therapies for this aggressive breast cancer. The distinction of metastatic lung adenocarcinoma to the breast and invasive breast carcinoma has significant prognostic and therapeutic implications. The determination can be challenging because both primary tumors can express estrogen receptor and/or HER2 by IHC, creating a diagnostic dilemma.

OBJECTIVES

- To provide a practical update on the use of IHC markers in differential diagnoses in breast lesions, including benign, atypical, precancerous, and malignant tumors; to highlight recently published research findings on novel IHC markers in triple-negative breast carcinoma cases; and to reinforce the importance of IHC use as an ancillary tool in distinguishing metastatic lung adenocarcinoma to the breast from primary breast carcinoma using real case examples.

DATA SOURCES

- PubMed (US National Library of Medicine, Bethesda, Maryland) literature review and authors' research data and personal experiences were used in this review.

CONCLUSIONS

- Immunohistochemistry has an important role in making differential diagnoses in breast lesions in morphologically equivocal settings; recognizing IHC expression status in the exceptions among these lesions will aid in the correct diagnosis of challenging breast cases. Studies suggest that androgen receptor, p16, p53, GATA3, and PELP1 may have potential diagnostic, prognostic, and predictive value in triple-negative breast carcinoma cases; these findings may provide insight and a greater understanding of the tumor biology in triple-negative breast carcinomas. In distinguishing metastatic estrogen receptor-positive or HER2⁺ lung adenocarcinoma to the breast from primary breast carcinoma, napsin A, TTF-1, and GATA3 comprise a useful IHC panel.

Papillary Lesions of the Breast: An Update

CONTEXT

-Papillary lesions of the breast, characterized by the presence of arborescent fibrovascular cores that support epithelial proliferation, constitute a heterogeneous group of neoplasms with overlapping clinical manifestation and histomorphologic features, but may have divergent biological behavior. These lesions are exclusively intraductal neoplasms, although an invasive carcinoma may rarely have a predominantly papillary architecture. Although recognition of a papillary architecture is typically not challenging, the histologic distinction of these entities is not always straightforward. Historically, different terminologies and variable criteria have been proposed for a given entity by various authorities. The difficulty in classifying these lesions has been further confounded by the scarcity of data and the heterogeneity across different studies with regard to the molecular genetic characteristics of this group of lesions.

OBJECTIVE

-To provide an overview focusing on the current concepts in the diagnosis and classification of papillary lesions of the breast incorporating recent molecular genetic advances.

DATA SOURCES

-Data were obtained from pertinent peer-reviewed English-language literature.

CONCLUSIONS

-The recent evolution of molecular techniques has enhanced our knowledge of the pathogenesis of papillary carcinomas of the breast. This, along with emerging outcome studies, has led to prognosis-based reclassification of some of these entities. Additional studies focusing on the molecular signatures are needed to identify potential decision tools to further stratify these lesions with respect to prognostic significance.

Pathological criteria and practical issues in papillary lesions of the breast - a review

Papillary lesions of the breast include a broad spectrum of lesions, ranging from benign papilloma, papilloma with atypical ductal hyperplasia (ADH) or ductal carcinoma in situ (DCIS) to papillary carcinoma. The accurate diagnosis of mammary papillary lesions is a challenge for pathologists, owing to the overlapping features among these lesions. In this review, some of the diagnostic criteria of papillary lesions are discussed, with special emphasis on some key morphological features, namely fibrovascular cores, epithelial proliferation in a solid pattern, intraductal papilloma complicated by ADH or DCIS, and invasion and its mimics. The roles of immunohistochemistry, and the interpretation of myoepithelial cell markers, hormone receptors, and high molecular weight cytokeratin, are addressed. Finally, novel biomarkers and genetic aberrations in papillary lesions are summarized.

Intracystic papillary carcinoma of the breast: A SEER database analysis of implications for therapy

BACKGROUND

Intracystic papillary carcinoma (IPC) of the breast is a rare breast malignancy with an indolent course. However, patients can develop metastatic disease. Indications for surgery and radiotherapeutic management have not been well elucidated.

METHODS

We identified 2649 female patients with IPC from the Surveillance, Epidemiology, and End Results (SEER) registry. Differences in demographics, clinical features and survival of patients were assessed using the Kaplan-Meier method and Cox regression.

RESULTS

Median age was 67 years. The majority of patients were white with Stage 0 disease. Most patients had lymph node evaluation and only 34% received radiation therapy. Using a log-rank test, survival was significantly better in Caucasian compared to African-American patients, patients with early stage disease, negative lymph nodes and those who received radiation (all p < 0.0001). In a Cox regression survival model adjusting for age, stage and grade, patients who were African-American (hazard ratio [HR] 2.0, CI 1.4-2.8; p < 0.0001) had a significantly higher risk of death than Caucasians. Patients who received radiation therapy (HR 0.5, CI 0.3-0.7; p = 0.0003) had a lower chance of death than patients that did not undergo radiation.

CONCLUSION

Overall, IPC has a good prognosis. Survival is improved in Caucasian patients and in patients who receive radiation therapy. Radiation therapy should be offered to women with IPC who undergo breast conserving surgery.

Intracystic Papillary Carcinoma of the Breast in a Male Patient

We report a case of intracystic papillary carcinoma of the right breast in a 59-year old man presenting with bloody nipple discharge for 1 week prior to presentation. Mammography, ultrasonography, and core needle aspiration were consistent with intracystic papillary carcinoma. The patient underwent right simple mastectomy. Pathology was also consistent with low grade intracystic papillary carcinoma. The 21-gene assay revealed a recurrence score of 0, corresponding to a 3% risk of distant recurrence at 10 years. A patient did not receive chemotherapy or post-mastectomy radiotherapy. The patient was placed on tamoxifen and has been free of disease to date.

Papillary carcinoma of breast: Minireview

The term “intracystic papillary ductal carcinoma in situ” constitutes only 0.5% to 1% of all breast cancers. It is usually seen in postmenopausal age group. Herein, we are presenting a minireview about this unusual breast malignancy usually difficult to diagnose on clinical grounds and highlighting modalities of diagnosis and management.

Intracystic Papillary Carcinoma in Male Breast with High Nuclear Grade: A Case Report

Intracystic papillary carcinoma (IPC) in men is an extremely rare disease that accounts for less than 1% of all malignancies with only a few case presentations published so far. This report presents a case of 53-year-old male, who presented a painless swelling of his left breast. The left breast mass was 6 cm maximally and was found to be non-invasive IPC. The tumour is consistently positive for GCDFP-15, ER or PR and negative for HER-2. It consists of predominantly fibrovascular stromal lined by monotonous epithelial cells retaining intermediate to high histological grade with a high nuclear cytoplasmic ratio. In addition, increased numbers of mitotic figures were also seen. Chest X-ray, liver ultrasound and bone centigram showed no evidence of distant metastases. In short, this is the first case report from Saudi Arabia of a male having IPC, with increased number of mitotic figures and high nuclear grades.

Endocrine mucin-producing sweat gland carcinoma: a study of three cases and CK8, CK18 and CD5/6 immunoexpression

Endocrine mucin-producing sweat gland carcinoma is a cutaneous adnexal tumor that is rarely reported in the literature. We identified only 29 previously reported cases. All these cases share some clinical morphologic and immunohistochemical features. Among the immunohistochemical markers, cytokeratins 5/6, 8 and 18 (CK5/6, CK8 and CK18) had not been previously studied in this tumor. Although studies with cytokeratin Cam5.2 exist, we know at present that this marker does not correspond to antibodies CK8/18, but rather to CK7 and CK8. We studied three examples of endocrine mucin-producing sweat gland carcinoma with 18 immunostains. Our cases showed an immunoprofile CK8+, CK18+, CK5/6- (or only focally positive), CK7+, GCDFP-15+ (2 cases), estrogen receptor+, progesterone receptor+, HER2-, neuron-specific enolase + (2 cases), anti-synaptophysin+, chromogranin A +, CD56 variable (1 case +, 1 case-), CD57-, anti-human D2-40- (two cases), p63- or focally positive, smooth muscle actin + with variable pattern of expression and smooth muscle myosin heavy chain expressed in a peripheral discontinuous layer in some nodules, but absent in most.

Papillary and neuroendocrine breast lesions: the WHO stance

In this review, we highlight adaptations in the WHO 2012 classification of papillary and neuroendocrine breast lesions as compared with the previous 2003 version. Consensus criteria for distinguishing atypical ductal hyperplasia from ductal carcinoma in situ within an intraductal papilloma are proposed. The absence of myoepithelial cells around the wall of an encapsulated papillary carcinoma, although raising consideration of an indolent tumour with minimal invasion, is currently regarded as in-situ disease for staging purposes. The majority of solid papillary carcinomas are classified as in-situ tumours, but lesions with irregular tumour islands within desmoplastic stroma may be considered to be invasive. The diagnosis of solid papillary carcinoma without further qualification as either in-situ or invasive disease is discouraged. When invasive papillary carcinoma is seen in the breast, metastatic papillary carcinoma from other organ sites needs to be excluded. WHO 2012 classifies neuroendocrine breast tumours as well-differentiated neuroendocrine tumour, small-cell carcinoma, and invasive breast carcinoma with neuroendocrine differentiation. There is currently no clinical impact of identifying neuroendocrine differentiation in conventional invasive breast carcinomas, apart from acknowledging its frequent occurrence in subtypes such as the hypercellular variant of mucinous carcinoma and solid papillary carcinoma.

Application of immunohistochemistry in breast pathology: a review and update

CONTEXT

Immunohistochemistry is a valuable tool in routine breast pathology, used for both diagnostic and prognostic parameters. The diagnostic immunomarkers are the scope of this review. Most breast lesions can be diagnosed on routine hematoxylin-eosin sections; however, in several scenarios, such as morphologically equivocal cases or metastatic tumors of unknown primary, the appropriate application of immunohistochemistry adds true value in reaching an accurate diagnosis.

OBJECTIVE

To evaluate the diagnostic utility of the most commonly studied immunomarkers in the field of breast pathology by review of the literature, using the database of indexed articles in PubMed (US National Library of Medicine, Bethesda, Maryland) from 1976 to 2013.

DATA SOURCES

Literature review, and author's research data and personal practice experience.

CONCLUSIONS

The appropriate use of immunohistochemistry by applying a panel of immunomarkers and using a standardized technical and interpretational method will complement the morphologic assessment and aid in the accurate classification of difficult breast lesions and the identification of metastasis from a breast primary.

Lattice-based model of ductal carcinoma in situ suggests rules for breast cancer progression to an invasive state

Ductal carcinoma in situ (DCIS) is a heterogeneous group of non-invasive lesions of the breast that result from abnormal proliferation of mammary epithelial cells. Pathologists characterize DCIS by four tissue morphologies (micropapillary, cribriform, solid, and comedo), but the underlying mechanisms that distinguish the development and progression of these morphologies are not well understood. Here we explored the conditions leading to the emergence of the different morphologies of DCIS using a two-dimensional multi-cell lattice-based model that incorporates cell proliferation, apoptosis, necrosis, adhesion, and contractility. We found that the relative rates of cell proliferation and apoptosis governed which of the four morphologies emerged. High proliferation and low apoptosis favored the emergence of solid and comedo morphologies. In contrast, low proliferation and high apoptosis led to the micropapillary morphology, whereas high proliferation and high apoptosis led to the cribriform morphology. The natural progression between morphologies cannot be investigated in vivo since lesions are usually surgically removed upon detection; however, our model suggests probable transitions between these morphologies during breast cancer progression. Importantly, cribriform and comedo appear to be the ultimate morphologies of DCIS. Motivated by previous experimental studies demonstrating that tumor cells behave differently depending on where they are located within the mammary duct in vivo or in engineered tissues, we examined the effects of tissue geometry on the progression of DCIS. In agreement with our previous experimental work, we found that cells are more likely to invade from the end of ducts and that this preferential invasion is regulated by cell adhesion and contractility. This model provides additional insight into tumor cell behavior and allows the exploration of phenotypic transitions not easily monitored in vivo.

Breast cancer is a complex disease that affects women worldwide. One heterogeneous group of lesions, ductal carcinoma in situ (DCIS), often begins as a nonmalignant disease but can readily progress if left untreated. The progression of this disease is not well understood because DCIS is typically removed upon detection. Therefore, computational models might help predict whether DCIS will remain nonmalignant or progress towards invasive ductal carcinoma. Here we used a multi-cell lattice-based model to explore the relative effects of cell proliferation, death, division axis, adhesion and contractility on the development and progression of DCIS. We also examined the emergence and progression of DCIS in physiologically relevant geometries of the mammary duct. Our model suggests several plausible progressions between morphologies of DCIS, and predicts that some regions of a duct are preferential for tumor cell invasion.

Integrative genomic and transcriptomic characterization of papillary carcinomas of the breast

Papillary carcinoma (PC) is a rare type of breast cancer, which comprises three histologic subtypes: encapsulated PC (EPC), solid PC (SPC) and invasive PC (IPC). Microarray‐based gene expression and Affymetrix SNP 6.0 gene copy number profiling, and RNA‐sequencing revealed that PCs are luminal breast cancers that display transcriptomic profiles distinct from those of grade‐ and estrogen receptor (ER)‐matched invasive ductal carcinomas of no special type (IDC‐NSTs), and that the papillary histologic pattern is unlikely to be underpinned by a highly recurrent expressed fusion gene or a highly recurrent expressed mutation. Despite displaying similar patterns of gene copy number alterations, significant differences in the transcriptomic profiles of EPCs, SPCs and IPCs were found, and may account for their different histologic features.

Papillary carcinomas of the breast display distinctive transcriptomic profiles.

Proliferation‐related genes are expressed at low levels in papillary carcinomas.

Papillary carcinomas are unlikely to be underpinned by a highly recurrent fusion gene.

Papillary carcinomas are unlikely to be underpinned by a highly recurrent expressed mutation.

A Brief Overview of the WHO Classification of Breast Tumors, 4th Edition, Focusing on Issues and Updates from the 3rd Edition

The WHO Classification of Tumors of the Breast, 4th edition, is an update to the 3rd edition that was published in 2003, and covers all neoplastic and preneoplastic lesions of the breast. Changes to the 4th edition include new aspects and changes to the terminology that reflect our present-day knowledge of these lesions. Definitions for histopathological diagnosis are complemented by a description of clinical features, epidemiology, macroscopy, genetics, and prognostic and predictive features. In this review of the WHO classification, we have focused on invasive carcinomas, precursor lesions, and some benign epithelial proliferations.

Intracystic papillary carcinoma of breast: interrelationship with in situ and invasive carcinoma and a proposal of pathogenesis: array comparative genomic hybridization study of 14 cases

Classifying intracystic papillary carcinoma under invasive or in situ ductal carcinoma is still a matter of debate. The purpose of this study was to explore the genomic relationship of this tumor to its concurrent invasive ductal carcinoma and ductal carcinoma in situ using array comparative genomic hybridization. Intracystic papillary carcinoma cases were classified into three categories: pure, with concurrent ductal carcinoma in situ or with concurrent invasive ductal carcinoma. Each component was dissected using laser capture microdissection. DNA was extracted and array comparative genomic hybridization was performed. The test of difference in copy number changes among the three tumors was carried out using CGHMultiArray. Intracystic papillary carcinoma clustered with four of five concurrent ductal carcinoma in situ cases and with two of two invasive ductal carcinoma cases. Intracystic papillary carcinoma showed the highest proportions of genome copy number aberration, followed by ductal carcinoma in situ, and then by invasive ductal carcinoma (P=0.06). Comparing intracystic papillary carcinoma with invasive ductal carcinoma vs without invasive ductal carcinoma, the former had 11q22.1-23.3 loss (P=0.031) and chr5 gain (P=0.085), and was enriched with matrix metalloproteinase genes. Comparing intracystic papillary carcinoma with ductal carcinoma in situ vs without ductal carcinoma in situ, the former had gain in 5q35.3 (P=0.041), 8q24.3 (P=0.041) and 21q13.2 to 21q13.31 (P=0.011). Comparing intracystic papillary carcinoma with ductal carcinoma in situ, the latter acquired a group of genes involved in cell adhesion and motility, whereas intracystic papillary carcinoma differentially expressed genes that are involved in papillary carcinomas of other organs (thyroid and kidney). We conclude that the overall molecular change in intracystic papillary carcinoma is closer to ductal carcinoma in situ than to invasive ductal carcinoma, which may explain the indolent behavior of this tumor. We offer herein a proposal of intracystic papillary carcinoma pathogenesis through its relation to invasive ductal carcinoma and ductal carcinoma in situ.

A novel diagnostic method targeting genomic instability in intracystic tumors of the breast

BACKGROUND

Even after needle biopsy, the preoperative differential diagnoses of intracystic tumors of the breast are challenging because of their nonspecific radiological characteristics and subtle cytological and histological appearance. The aim of this study is to investigate a novel diagnostic method, targeting genomic instability (GIN) in intracystic tumors of the breast, using tumor DNA from samples obtained by fine-needle aspiration biopsy (FNAB).

METHODS

Thirteen consecutive intracystic tumors of the breast, including five cancers and eight benign tumors, were studied. Three FNAB passages per tumor were used for array comparative genomic hybridization (aCGH) analysis to quantify GIN in each tumor. Tumor DNA from the main tumor, taken from formalin-fixed, paraffin-embedded (FFPE) blocks corresponding to FNAB samples, was also analyzed to compare cytogenetic profiles between these sample types.

RESULTS

After three FNAB passages, an average of 7.09 μg (0.24-25.0 μg) of DNA was obtained. The quality of the DNA and the aCGH data was excellent, as judged by the mean derivative log ratio spread (DLRSpread) of 0.22 (0.15-0.29). The cytogenetic profiles of paired FNAB and main tumor FFPE samples were highly similar, with an average concordance rate of 97.7 % (81.2-100 %). aCGH analysis from FNAB samples showed significantly more GIN in cancers than in benign tumors, with mean frequencies of aberrant chromosomal regions of 17.5 and 0.34 %, respectively (Wilcoxon's rank sum test, P = 0.0016).

CONCLUSIONS

Our novel diagnostic method, which targets GIN, can clearly distinguish cancers from benign tumors of breast intracystic lesions with minimal invasion, thereby avoiding the need for surgical excisional biopsy.

Unusual case of insitu (intracystic) papillary carcinoma of breast

The term “intracystic papillary ductal carcinoma in situ”, has recently changed and is now more appropriately referred to as “intracystic papillary carcinoma’’ constituting only 0.5% to 1% of all breast cancers. Herein, we discuss an unusual case of intracystic insitu papillary carcinoma of breast in a postmenopausal woman, the diagnosis of which was made on histopathology and confirmed by immunohistochemistry. Patient responded well to postoperative adjuvant radiotherapy without any recurrence, thereby preventing further morbidity and mortality related to invasion or tumor progression. So careful histopathological evaluation is the mainstay to arrive at the correct diagnosis to avoid untoward complications related to under diagnosis and /over diagnosis.

Breast carcinoma with tubulopapillary features: a variant of papillary carcinoma with a stronger correlation with predictors of adverse prognosis

Papillary carcinoma of the breast consists of 3 morphologically distinct established subtypes: encapsulated papillary carcinoma, solid papillary carcinoma, and invasive papillary carcinoma. Papillary carcinoma is one of the special types of breast cancer and, as such, carries a more favorable prognosis. We sought to identify primary breast tumors with tubulopapillary morphology and correlate this finding with predictors of adverse prognosis. We investigated our pathology files for breast tumors exhibiting tubulopapillary features. The dominant morphology consisted of infiltrating gaping tubules with intratubular papillary projections. The study group consisted of 12 cases of papillary carcinoma with tubulopapillary features. A control group of 17 cases of papillary carcinoma were selected consisting of 4 encapsulated papillary carcinomas, 3 solid papillary carcinomas, and 10 invasive papillary carcinomas. The study group showed significantly higher mitotic rate, ki67 proliferation index, nuclear grade 3, lymphovascular invasion, p53 overexpression, unfavorable biomarker signature, and axillary nodal involvement compared to the control group (P = .01, .01, .04, .01, .007, .0001, .03, respectively). Invasive breast carcinomas with tubulopapillary features demonstrate significant correlation with predictors of adverse prognosis compared to ordinary papillary carcinomas. Larger studies with survival analysis are required to confirm aggressiveness in this group of breast cancers.

Pathology of invasive breast disease

Invasive breast cancers constitute a heterogeneous group of lesions. Although the most common types are ductal and lobular, this distinction is not meant to indicate the site of origin within the mammary ductal system. The main purpose of the identification of specific types of invasive breast carcinoma is to refine the prediction of likely behavior and response to treatment also offered by the other major prognostic factors, including lymph node stage, histologic grade, tumor size, and lymphovascular invasion.

Intracystic papillary carcinoma of breast: report of three cases and review of the literature

Intracystic papillary carcinoma (IPC) of the breast is a rare malignant tumour, found mainly but not exclusively in elderly women. IPC may be asymptomatic or presents with a palpable mass or blood-stained nipple discharge. The tumour is encysted within a dilated duct with arborisation of the fibrovascular stroma and contains nodules of papillary carcinoma surrounded by a thick fibrous capsule. Frequently excisional biopsy is required for diagnosis. The mainstay of treatment is breast-conserving surgery or mastectomy. Sentinel node biopsy could be considered in invasive cases. Adjuvant radiotherapy (XRT) and/or endocrine therapy is considered in appropriate cases. Prognosis is excellent. We report three such cases of IPC, in elderly women, which were successfully treated.

Solid papillary carcinoma of the breast: a pathologically and clinically distinct breast tumor

Solid papillary carcinomas are tumors morphologically characterized by round, well-defined nodules composed of low-grade ductal cells separated by fibrovascular cores. These tumors are rare and affect predominantly older women. Although they are considered in situ carcinomas, debate and uncertainty still exist regarding their true nature, because immunohistochemistry for myoepithelial cells has shown absence of myoepithelial cell layer along the epithelial-stromal interface of the tumor in many cases. Clinically, these tumors present as a palpable, centrally located mass or as bloody nipple discharge. Pathologically, solid papillary carcinomas exhibit low-grade features, and often the tumors display neuroendocrine and mucinous differentiation. In the majority of cases an associated invasive carcinoma is present, with colloid and neuroendocrine carcinomas being the most common. The pathologic differential diagnosis is broad and ranges from benign to malignant lesions. The treatment for solid papillary carcinomas is surgical excision. When invasive carcinoma is not present, the prognosis is excellent.

Intracystic papillary carcinoma of the breast in a male patient: a case report

Breast carcinoma is an uncommon neoplastic condition among man, accounting for not more than 1% of all breast cancers. Intracystic papillary carcinoma in man is an extremely rare condition and represents only 5-7,5% of all male breast carcinomas. Clinical and radiological manifestations of intracystic papillary carcinomas are not specific. Pathologic diagnosis can be difficult at classical histological examination and identification of myoepithelial cells layer by immunohistochemical study can be useful. Adjuvant therapy is still controversial and prognosis is excellent. We report a case of this rare histological type of breast cancer in 48-year-old male patient and review the literature.

Intracystic papillary carcinoma of the breast: report of three cases and literature review

Intracystic papillary carcinoma is a rare malignant tumor of the breast. It occurs communally in postmenopausal women. Clinically it can be asymptomatic or manifested by a breast mass or a nipple discharge. On imaging intracystic papillary carcinoma has usually benign features. Pathologic diagnosis can be difficult at classical histological examination and identification of myoepithelial cells layer by immunohistochemical study can be useful. In the majority of cases of pure intracystic papillary carcinoma, conservative management is possible. Adjuvant therapy is still controversial and prognosis is excellent. We report three cases of intracystic papillary carcinoma diagnosed on immunohistochemical examination and managed with conservative surgery.

Immunophenotypic and genomic characterization of papillary carcinomas of the breast

Papillary carcinomas are a special histological type of breast cancer and have a relatively good outcome. We characterized the genomic and phenotypic characteristics of papillary carcinomas to determine whether they would constitute an entity distinct from grade- and oestrogen receptor (ER)-matched invasive ductal carcinomas of no special type (IDC-NSTs). The phenotype of 63 papillary carcinomas of the breast and grade- and ER-matched IDC-NSTs was determined by immunohistochemistry. DNA of sufficient quality was extracted from 49 microdissected papillary carcinomas and 49 microdissected grade- and ER-matched IDC-NSTs. These samples were subjected to high-resolution microarray-based comparative genomic hybridization (aCGH) and Sequenom MassARRAY sequencing analysis of 19 known oncogenes. Papillary carcinomas were predominantly of low histological grade, expressed immunohistochemical markers consistent with a luminal phenotype, and a lower rate of lymph node metastasis and p53 expression than grade- and ER-matched IDC-NSTs. Papillary carcinomas displayed less genomic aberrations than grade- and ER-matched IDC-NSTs; however, the patterns of gene copy number aberrations found in papillary carcinomas were similar to those of ER- and grade-matched IDC-NSTs, including 16q losses. Furthermore, PIK3CA mutations were found in 43% and 29% of papillary carcinomas and grade- and ER-matched IDC-NSTs, respectively. The genomic profiles of encapsulated, solid and invasive papillary carcinomas, the three morphological subtypes, were remarkably similar. Our results demonstrate that papillary carcinomas are a homogeneous special histological type of breast cancer. The similarities in the genomic profiles of papillary carcinomas and grade- and ER-matched IDC-NSTs suggest that papillary carcinomas may be best positioned as part of the spectrum of ER-positive breast cancers, rather than as a distinct entity. Furthermore, the good prognosis of papillary carcinomas may stem from the low rates of lymph node metastasis and p53 expression, low number of gene copy number aberrations and high prevalence of PIK3CA mutations.

Intracystic Papillary Carcinoma of the Breast in Males. In Search of the Optimal Treatment for this Rare Disease

Intracystic papillary carcinoma (IPC) of the breast in men is an extremely infrequent disease, and it appears to have a good prognosis. Because of this, histological findings are of great importance in the decision-making process regarding treatment. Clinical examination, radiological and histological assessments are required for early detection. Adequate surgical excision with negative margins is mandatory. However, the role of sentinel node biopsy has not been evaluated in male IPC. It appears that sentinel node biopsy may be an excellent alternative to radical axillary dissection in patients with IPC and associated ductal carcinoma in situ or invasive carcinoma. Nevertheless, due to the rarity of IPC and its confusing histopathological classification and staging, there are still no clear guidelines as far as IPC treatment is concerned.