Atypical cystic lobules in patients with lobular neoplasia

Are Columnar Cell Lesions the Earliest Non-Obligate Precursor in the Low-Grade Breast Neoplasia Pathway?

Columnar cell lesions (CCLs) of the breast comprise a spectrum of morphologic alterations of the terminal duct lobular unit involving variably dilated and enlarged acini lined by columnar epithelial cells. The World Health Organization currently classifies CCLs without atypia as columnar cell change (CCC) and columnar cell hyperplasia (CCH), whereas flat epithelial atypia (FEA) is a unifying term encompassing both CCC and CCH with cytologic atypia. CCLs have been increasingly recognized in stereotactic core needle biopsies (CNBs) performed for the assessment of calcifications. CCLs are believed to represent the earliest non-obligate precursor of low-grade invasive breast carcinomas as they share molecular alterations and often coexist with entities in the low-grade breast neoplasia pathway. Despite this association, however, the risk of progression of CCLs to invasive breast carcinoma appears low and may not exceed that of concurrent proliferative lesions. As the reported upgrade rates of pure CCL/FEA when identified as the most advanced high-risk lesion on CNB vary widely, the management of FEA diagnosed on CNB remains controversial. This review will include a historical overview of CCLs and will examine histologic diagnostic criteria, molecular alterations, prognosis and issues related to upgrade rates and clinical management.

Preneoplasia of the Breast and Molecular Landscape

The current model of human breast cancer progression proposes a linear multi-step process which initiates as flat epithelial atypia (FEA), progresses to atypical ductal hyperplasia (ADH), evolves into ductal carcinoma in situ (DCIS) and culminates in the potentially lethal stage of invasive ductal carcinoma. FEA commonly coexists with well-developed examples of ADH, low-grade DCIS, lobular neoplasia and tubular carcinoma. These findings and those of recent genetic studies suggest that FEA is a neoplastic lesion that may represent a precursor to or the earliest morphologic manifestation of ductal carcinoma in situ. At the same time, many of the genomic changes of ADH are also shared by common sporadic breast cancer, consistent with a high risk for future development of metachronous breast cancer.

Intraductal patient-derived xenografts of estrogen receptor α-positive breast cancer recapitulate the histopathological spectrum and metastatic potential of human lesions

Estrogen receptor α‐positive (ER‐positive) or ‘luminal’ breast cancers were notoriously difficult to establish as patient‐derived xenografts (PDXs). We and others recently demonstrated that the microenvironment is critical for ER‐positive tumor cells; when grafted as single cells into milk ducts of NOD Scid gamma females, >90% of ER‐positive tumors can be established as xenografts and recapitulate many features of the human disease in vivo. This intraductal approach holds promise for personalized medicine, yet human and murine stroma are organized differently and this and other species specificities may limit the value of this model. Here, we analyzed 21 ER‐positive intraductal PDXs histopathologically. We found that intraductal PDXs vary in extent and define four histopathological patterns: flat, lobular, in situ and invasive, which occur in pure and combined forms. The intraductal PDXs replicate earlier stages of tumor development than their clinical counterparts. Micrometastases are already detected when lesions appear in situ. Tumor extent, histopathological patterns and micrometastatic load correlate with biological properties of their tumors of origin. Our findings add evidence to the validity of the intraductal model for in vivo studies of ER‐positive breast cancer and raise the intriguing possibility that tumor cell dissemination may occur earlier than currently thought. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Precursor Lesions of the Low-Grade Breast Neoplasia Pathway

The nonobligate precursor lesions columnar cell change/hyperplasia and flat epithelial atypia, atypical ductal hyperplasia and atypical lobular hyperplasia, lobular carcinoma in situ, and low-grade ductal carcinoma in situ share morphologic, immunophenotypic, and molecular features supporting the existence of a low-grade breast neoplasia pathway. The practical implication for pathologists is that the identification of one of these lesions should prompt careful search for others. From a clinical management perspective, however, their designation as "precursor lesions" should not be overemphasized, as the risk of progression among the earliest lesions is exceedingly low. Factors determining which lesions will progress remain unknown.

Flat epithelial atypia and risk of breast cancer: A Mayo cohort study

BACKGROUND

Based on its cytologic features, and its co-occurrence with atypical hyperplasia and breast cancer, flat epithelial atypia (FEA) has been proposed as a precursor lesion on the pathway to the development of breast cancer. It is often referred to as an "atypical" or high-risk lesion. However, to the authors' knowledge, the long-term risk of breast cancer in women with FEA is undefined.

METHODS

Specimens with FEA were identified among excisional breast biopsies in the Mayo Clinic Benign Breast Disease Cohort, which includes 11,591 women who had benign biopsy findings at the Mayo Clinic in Rochester, Minnesota between 1967 and 2001. Breast cancer risk among subsets of patients with FEA and nonproliferative, proliferative, and atypical hyperplasia (AH) was assessed using standardized incidence ratios (SIRs) compared with the Iowa Surveillance, Epidemiology, and End Results registry.

RESULTS

FEA was identified in 282 women (2.4%); 130 had associated AH (46%) and 152 (54%) were classified as having proliferative disease without atypia (PDWA). With median follow-up of 16.8 years, the SIR for breast cancer in patients with AH plus FEA was 4.74 (95% confidence interval [95% CI], 3.17-6.81) versus 4.23 (95% CI, 3.44-5.13) for those with AH without FEA (P = .59). The SIR for patients with PDWA plus FEA was 2.04 (95% CI, 1.23-3.19) versus 1.90 (95% CI, 1.72-2.09) for patients with PDWA without FEA (P = .76).

CONCLUSIONS

FEA is an uncommon finding in women with benign breast disease. FEA does not appear to convey an independent risk of breast cancer beyond that of the associated PDWA or AH.

Pathologic Upgrade Rates on Subsequent Excision When Lobular Carcinoma In Situ Is the Primary Diagnosis in the Needle Core Biopsy With Special Attention to the Radiographic Target

Context.—Lobular carcinoma in situ (LCIS) as the primary pathologic diagnosis in a needle core biopsy is an infrequent finding, and the management of patients in this setting is controversial.

Objective.—To determine the rate of pathologic upgrade (defined as the presence of a clinically more-significant lesion in the subsequent excision) in patients with a primary pathologic diagnosis of LCIS in the needle core biopsy.

Design.—Patients with a primary diagnosis of LCIS in a needle core biopsy who underwent subsequent excision were identified. Core biopsies containing a concurrent high-risk lesion and cases with radiologic-pathologic discordance were excluded. The presence of selected microscopic features in the needle core biopsy was correlated with pathologic upgrade. Microscopic findings were correlated with the radiographic target in the needle core biopsy.

Results.—Sixty-one women with primary LCIS in their needle core biopsy showed a 10% pathologic upgrade rate. The percentage of cores involved by LCIS was significantly associated with pathologic upgrade (P= .04), whereas the remaining measured parameters were not. When LCIS represented the radiographic target, the pathologic upgrade rate was 18%, whereas when it was an incidental finding, the pathologic upgrade rate was 4%.

Conclusions.—It may be reasonable for patients with primary, yet incidental, LCIS on needle core biopsy to be managed in a nonsurgical fashion. Larger studies are needed to confirm our findings.

Morphological parameters of flat epithelial atypia (FEA) in stereotactic vacuum-assisted needle core biopsies do not predict the presence of malignancy on subsequent surgical excision

Flat epithelial atypia (FEA) may represent the earliest precursor of low-grade breast cancer and often coexists with more advanced atypical proliferative breast lesions such as atypical ductal hyperplasia (ADH) and lobular intraepithelial neoplasia (LIN). The present study aims to investigate the association between morphological parameters of FEA and presence of malignancy at surgical excision (SE) and the clinical significance of the association of FEA with ADH and/or LIN. This study included 589 cases of stereotactic 11-gauge vacuum-assisted needle core biopsy (VANCB), reporting a diagnosis of FEA, ADH or LIN with subsequent SE from 14 pathology departments in Italy. Available slides were reviewed, with 114 (19.4 %) showing a malignant outcome at SE. Among the 190 cases of pure FEA, no statistically significant association emerged between clinical-pathological parameters of FEA and risk of malignancy. Logistic regression analyses showed an increased risk of malignancy according to the extension of ADH among the 275 cases of FEA associated with ADH (p = 0.004) and among the 34 cases of FEA associated with ADH and LIN (p = 0.02). In the whole series, a statistically significant increased malignancy risk emerged according to mammographic R1-R3/R4-R5 categories (OR = 1.56; p = 0.04), extension (OR = 1.24; p = 0.04) and grade (OR = 1.94; p = 0.004) of cytological atypia of FEA. The presence of ADH was associated with an increased malignancy risk (OR = 2.85; p < 0.0001). Our data confirm the frequent association of FEA with ADH and/or LIN. A diagnosis of pure FEA on VANCB carries a 9.5 % risk of concurrent malignancy and thus warrants follow-up excision because none of the clinical-pathological parameters predicts which cases will present carcinoma on SE.

Management of lobular carcinoma in-situ and atypical lobular hyperplasia of the breast--a review

OBJECTIVES

To determine the incidence of malignancy (invasive carcinoma or DCIS) in patients diagnosed with lobular neoplasia (B3) on core needle biopsy (CNB) of breast lesions by reviewing the published literature.

METHODS

Medline, Embase, OVID-database and reference lists were searched to identify and review all English-language articles addressing the management of LN diagnosed on CNB. Studies on mixed breast pathologies were excluded.

RESULTS

Of 1229 LN diagnosed on CNB, 789 (64%) underwent surgical excision. 211 (27%) of excisions contained either DCIS or invasive disease. 280 of the excision specimens were classified as ALH, 241 as LCIS, 22 as pleomorphic LCIS and 246 unspecified LN on the original CNB. After surgical excision, 19% of the ALH cases, 32% of the LCIS cases and 41% of the PLCIS cases, contained malignancy. 29% of the unspecified LNs were upgraded to malignancy. The higher incidence of malignancy within excision specimens for LCIS and PLCIS compared to ALH was significant (P < 0.04, <0.003 respectively).

CONCLUSION

There is a significant underestimation of malignancy in patients diagnosed with breast LN on CNB. 27% cases of CNB-diagnosed LN were found to contain malignancy following surgical excision. All patients diagnosed with LN on CNB should be considered for surgical excision biopsy.

Flat epithelial atypia on breast needle core biopsy: a retrospective study with clinical-pathological correlation

There are limited data to guide clinical management when flat epithelial atypia (FEA) is identified in breast needle core biopsies (NCBs). Our objectives were to determine the frequency of malignancy in subsequent breast excisions following NCB diagnosis of FEA, and to characterize the pathological and clinical features of associated tumors. Two hundred and fifty-six breast NCBs from a retrospective search (January 1999-July 2007) were blindly reviewed for FEA/other columnar cell lesions (CCLs). NCBs with co-existing carcinoma were excluded. The study included 211 NCBs: 116 (55%) with CCLs without atypia; 40 (19%) with CCLs with atypical ductal hyperplasia (ADH), 15 (7%) with FEA and 40 (19%) with FEA and ADH; 94 cases had follow-up excisions. Ductal carcinoma in situ and/or invasive carcinoma were present in: 4/26 (15%) excisions with CCLs on NCB, 11/30 (37%) with CCLs + ADH, 1/7 (14%) with FEA alone, and 9/31 (29%) with FEA + ADH. (a) FEA was more frequently seen with ADH, than without ADH in NCBs, (b) FEA and CCLs were more frequently associated with malignancy when with ADH, and (c) tumors excised following NCB diagnosis of FEA+/-ADH had favorable prognostic factors. A conservative excision is warranted following a NCB diagnosis of FEA and ADH, and may be warranted for FEA alone.

[Atypical ductal and lobular hyperplasia of the breast]

Atypical hyperplasia represents 4% of all benign breast diseases. There are two different types: atypical ductal hyperplasia and atypical lobular hyperplasia. Aside columnar cell lesion. They represent an early stage of some forms of low grade carcinoma in situ and invasive carcinomas. Atypical hyperplasia is a benign lesion with intermediate carcinologic risk and the existence of a concomitant aggressive lesion should be suspected. When atypical lesion is found on a biopsy specimen, surgical excision is recommended especially in case of atypical ductal hyperplasia. A regular supervision is recommended.

Lobular Carcinoma in Situ, Classical Type and Unusual Variants

The morphologic spectrum of lobular carcinoma in situ (LCIS) includes the classical type and unusual variants recently described. In this article we review the morphology of LCIS and highlight ways to distinguish it from its morphologic mimickers.

Flat Ductal Intraepithelial Neoplasia of the Breast: A Review of Diagnostic Criteria, Differential Diagnoses, Molecular-Genetic Findings, and Clinical Relevance—It Is Time to Appreciate the Azzopardi Concept!

Context.—More than 25 years ago, John G. Azzopardi described a distinctive intraepithelial neoplastic breast lesion, which he designated “clinging carcinoma in situ”; he considered it as another variant of ductal carcinoma in situ, an early lesion that can easily be missed because the changes are mainly cytologic rather than architectural. The lesion remained widely unrecognized and/or ignored until recent years when its neoplastic nature was confirmed at the molecular-genetic level.

Objective.—To deal with historical aspects of the evolving concept of “clinging” and to focus on several important issues such as characteristic morphologic features with particular attention to the diagnostic criteria and differential diagnoses, recent molecular-genetic findings, appropriate terminology and classification, as well as the significance of this type of lesion for both surgical pathologists and clinicians.

Data Sources.—A thorough search of the literature was performed and publications using a variety of designations including “clinging carcinoma in situ,” “flat epithelial atypia,” “ductal intraepithelial neoplasia-flat type,” “atypical cystic lobules,” “columnar cell change with atypia,” “columnar cell hyperplasia with or without atypia,” “columnar alteration with prominent apical snouts and secretion,” and so forth were reviewed.

Conclusions.—This distinctive lesion represents one of the earliest morphologically recognizable neoplastic alterations of the breast that is commonly associated with mammographically suspicious microcalcifications. It is characterized by mildly to severely atypical cells simply replacing the single layer of native epithelial cells in a flat fashion without appreciable proliferation; tufting, intraluminal bridging, micropapillary structures, and so forth are typically absent or very focal and minimal, if present at all. Based on the degree of cytologic atypia, low- and high-grade flat ductal intraepithelial neoplasia need to be separated. Although additional studies are needed to better understand the clinical significance of flat ductal intraepithelial neoplasia, several lines of evidence strongly support the concept of clinging. Indeed, as pointed out by Azzopardi, surgical pathologists need to pay more attention to the cytologic alterations of the breast lesions by analyzing the involved cell populations using high-power magnification.

Flat Epithelial Atypia of the Breast

Lesions of the breast characterized by enlarged terminal duct lobular units lined by columnar epithelial cells are being encountered increasingly in breast biopsy specimens. Some of these lesions feature cuboidal to columnar epithelial cells in which the lining cells exhibit cytologic atypia. The role of these lesions (recently designated "flat epithelial atypia" [FEA]) in breast tumor progression is still emerging. FEA commonly coexists with well-developed examples of atypical ductal hyperplasia, low-grade ductal carcinoma in situ, lobular neoplasia, and tubular carcinoma. These findings and those of recent genetic studies suggest that FEA is a neoplastic lesion that may represent a precursor to or the earliest morphologic manifestation of ductal carcinoma in situ. Additional studies are needed to better understand the biologic nature and clinical significance of these lesions.

Histologic associations and long-term cancer risk in columnar cell lesions of the breast: a retrospective cohort and a nested case-control study

BACKGROUND

Mammary columnar cell lesions with atypia have been receiving increased scrutiny in view of their association with atypical hyperplasia (AH) and carcinoma. However, the few retrospective outcome studies performed have failed to establish an increased risk for recurrence or carcinoma on long-term follow-up.

METHODS

The authors evaluated the overall cancer risk for 1261 biopsies with columnar cell lesions (CCL) in 4569 women from the Nashville Breast Cohort who were biopsied between 1969 and 1988. On the basis of Schnitt and Vincent-Salomon's classification, they also classified 229 biopsies with CCL into 3 categories: without hyperplasia or atypia, with hyperplasia lacking atypia, and with atypia. By using a nested case-control design, they compared the risks of invasive cancer associated with these 3 categories.

RESULTS

A 2- to 3-fold increase in the occurrence of AH in the presence of CCL versus in their absence (P< .005) was observed. Relative risk of invasive breast cancer for women with both AH and CCL compared with those with AH alone did not differ significantly (risk ratio [RR]=1.55; P= .29). The presence of CCL alone was associated with a mild increase in the overall cancer risk (RR=1.47; P= .05). In the nested case-control study, no significant risk difference was observed among the 3 categories of CCL.

CONCLUSIONS

The authors observed a positive association between CCL and AH. The possibility that CCL by themselves significantly elevate breast cancer risk is not well supported. However, a finding of CCL on benign breast biopsy may indicate the presence of AH, a more worrisome lesion.

Interobserver variability and aberrant E-cadherin immunostaining of lobular neoplasia and infiltrating lobular carcinoma

The distinction between lobular neoplasia and infiltrating lobular carcinoma from ductal neoplasia and infiltrating duct carcinoma with equivocal histologic features may present a challenge as this distinction has important therapeutic implications. Although E-cadherin staining has been of value in helping to make this determination, the variability of the E-cadherin staining pattern and the immunohistochemistry techniques can be problematic in clinical practice. A total of 161 cases of breast lesions previously diagnosed as lobular neoplasia and infiltrating lobular carcinoma were selected from the departmental files. Three surgical pathologists interpreted them in a blinded manner for the histology diagnoses and E-cadherin staining. E-cadherin staining was conducted on the paraffin-embedded sections of the breast lesions using two different source antibodies. Our results using morphology and E-cadherin stain agreed with the previous diagnoses of lobular neoplasia and infiltrating lobular carcinoma in 140 of 161 cases (86.9%). Among the 140 cases, three pathologists agreed with the morphologic diagnoses of lobular neoplasia and infiltrating lobular carcinoma in 100 (71.4%), two pathologists in 26 (18.6%) and one pathologist in 14 (10%). All three pathologists disagreed with the previous diagnoses of lobular neoplasia and infiltrating lobular carcinoma but reevaluated as ductal lesions in 21 cases (13.0%). E-cadherin staining was confirmatory in 136 of total 161 cases (84.5%) of both lobular and duct lesions by showing the loss of staining in lobular lesions and the presence of complete membrane staining in duct lesions. Aberrant E-cadherin reactions were retained weak or partial incomplete thin membrane reaction in lobular-type lesions and reduced membrane reaction in ductal-type lesions were seen in 25 of the total 161 cases (15.5%). E-cadherin immunoreaction with two different antibodies showed discrepant results in 5 of 78 cases tested (6.4%). This study illustrates (1) interobserver variability of the morphologic diagnoses of lobular neoplasia/infiltrating lobular carcinoma and duct neoplasia/infiltrating duct carcinoma, (2) the occasional presence of aberrant E-cadherin stain pattern in these breast lesions and (3) variability of E-cadherin immunostaining results by two different antibodies.

The significance of lobular neoplasia on needle core biopsy of the breast

The management of a core biopsy diagnosis of lobular neoplasia is controversial. Detailed radiological–pathological review of 47 patients with cores showing classical lobular neoplasia was performed (patients with pleomorphic lobular carcinoma in situ (LCIS) or associated risk lesions were considered separately). Immediate surgical excision in 25 patients showed invasive carcinoma in 7, ductal carcinoma in situ (DCIS) in 1 and pleomorphic LCIS in 1; radiological–pathological review showed that the core biopsy missed a mass in 5, missed calcification in 2 and that calcification appeared adequately sampled in 2. Nineteen patients had follow-up of at least 2 years. Four patients developed malignancy at the site of the core biopsy (invasive carcinoma in three, DCIS in one); one carcinoma was mammographically occult, one patient had dense original mammograms and two had calcifications apparently adequately sampled by the core. In conclusion, most carcinomas identified at the site of core biopsy showing lobular neoplasia were the result of the core missing the radiological lesion, emphasising the importance of multidisciplinary review and investigation of any discordance. Some carcinomas were found after apparently adequate core biopsy, raising the question of whether excision biopsy should be considered after all core biopsy diagnoses of lobular neoplasia.

The "Rosen Triad": tubular carcinoma, lobular carcinoma in situ, and columnar cell lesions

The histologic triad of tubular carcinoma (TC), columnar cell lesion (CCL), and lobular carcinoma in situ (LCIS) has been recognized, but has not yet been fully characterized. The "Rosen Triad"-named in tribute to its first categorical description by the eponymous pathologist-is a morphologic observation that may have important clinical and pathologic implications. To study these implications, the literature on the topic was reviewed. Our own institution's experience with this triad was also reviewed via a study of clinicopathologic material from all TCs diagnosed at excision during a 5-year period (2001 to 2006). The diagnosis of TC was confirmed in 86 of our cases, and relevant patient data were analyzed. TC was associated with some degree of CCL in all (100%, 86/86) cases and with LCIS in 53% (46/86) of cases. Although cases of TC that were associated with LCIS (vs. those not associated with LCIS) seemed to be slightly more likely to have multifocal TC, have another synchronous higher-grade invasive carcinoma and show nodal positivity, these differences were not found to be statistically significant (P<0.05). All 3 lesions (TC, CCL, and LCIS), whenever tested, were estrogen receptor positive, progesterone receptor-positive, and Her-2/neu negative. On the basis of our review of the literature and our own experience, until such time as the biologic explanation and clinical implication of this triad is further elucidated, we recommend that pathologists be aware of this triad and should proactively seek the other 2 lesions if any one of these elements of this triad is identified in any diagnostic breast tissue.

Flat epithelial atypia of the breast

Flat epithelial atypia is a presumably neoplastic alteration of terminal duct-lobular units that is characterized by the replacement of the native luminal epithelium by ductal cells demonstrating low-grade cytologic atypia. The atypical cells maintain a "flat" pattern of growth without evidence of architectural atypicality. Morphologic, immunohistochemical, and molecular investigations support that flat epithelial atypia represents an early step in the evolution of low-grade ductal carcinomas. It is frequently seen in association with atypical ductal hyperplasia, low-grade ductal carcinoma in situ, invasive tubular carcinoma, and lobular neoplasia. The risk for subsequent breast carcinoma remains to be defined, but flat epithelial atypia likely represents a nonobligate precursor with an extended time course to progression. Certain benign alterations may superficially mimic its appearance; careful attention to cytologic and architectural characteristics can help one distinguish these unrelated entities from flat epithelial atypia.

Clinical and pathologic features of ductal carcinoma in situ associated with the presence of flat epithelial atypia: an analysis of 543 patients

Flat epithelial atypia is an alteration of mammary terminal duct lobular units that is considered to be a precursor to, or early stage in, the development of some forms of ductal carcinoma in situ. No prior study has systematically evaluated the relationship between various clinico-pathologic features of ductal carcinoma in situ and the presence of coexistent flat epithelial atypia. An understanding of such relationships could provide insight into the connection between flat epithelial atypia and ductal carcinoma in situ. We reviewed slides from 543 ductal carcinoma in situ patients enrolled in a case-control study assessing epidemiologic and pathologic risk factors for local recurrence. We examined the association between the presence of flat epithelial atypia and various clinical factors, pathologic features of the ductal carcinoma in situ, and the presence of coexistent atypical ductal hyperplasia, lobular neoplasia, and non-atypical columnar cell lesions. In univariate analysis, the presence of flat epithelial atypia was significantly related to ductal carcinoma in situ nuclear grade (most common in low grade, least common in high grade; P<0.0001), architectural pattern (most common in micropapillary and cribriform, least common in comedo; P<0.0001), absence of comedo necrosis (P<0.001), absence of stromal desmoplasia (P=0.02) and absence of stromal inflammation (P=0.03). In multivariable analysis, features of ductal carcinoma in situ independently associated with flat epithelial atypia were micropapillary and cribriform patterns and absence of comedo necrosis. Additionally, flat epithelial atypia was significantly associated with the presence of atypical ductal hyperplasia, lobular neoplasia, and columnar cell lesions in both univariate and multivariable analyses. These observations provide support for a precursor-product relationship between flat epithelial atypia and ductal carcinoma in situ lesions that exhibit particular features such as micropapillary and cribriform patterns and absence of comedo necrosis.

Epithelial atypia in biopsies performed for microcalcifications. practical considerations about 2,833 serially sectioned surgical biopsies with a long follow-up

This study analyzes the occurrence of epithelial atypia in 2,833 serially sectioned surgical breast biopsies (SB) performed for microcalcifications (median number of blocks per SB:26) and the occurrence of subsequent cancer after an initial diagnosis of epithelial atypia (median follow-up 160 months). Epithelial atypia (flat epithelial atypia, atypical ductal hyperplasia, and lobular neoplasia) were found in 971 SB, with and without a concomitant cancer in 301 (31%) and 670 (69%) SB, respectively. Thus, isolated epithelial atypia were found in 670 out of the 2,833 SB (23%). Concomitant cancers corresponded to ductal carcinomas in situ and micro-invasive (77%), invasive ductal carcinomas not otherwise specified (15%), invasive lobular carcinomas (4%), and tubular carcinomas (4%). Fifteen out of the 443 patients with isolated epithelial atypia developed a subsequent ipsilateral (n = 14) and contralateral (n = 1) invasive cancer. The high slide rating might explain the high percentages of epithelial atypia and concomitant cancers and the low percentage of subsequent cancer after a diagnosis of epithelial atypia as a single lesion. Epithelial atypia could be more a risk marker of concomitant than subsequent cancer.

Flat epithelial atypia (DIN 1a, atypical columnar change): an underdiagnosed entity very frequently coexisting with lobular neoplasia

AIMS

Flat epithelial atypia of the breast [FEA; synonyms: ductal intraepithelial neoplasia (DIN) 1a, atypical columnar change] is increasingly recognized by pathologists and shows distinct genetic alterations. The aim of this study was to determine its biological significance as an incidental finding in breast biopsy specimens.

METHODS AND RESULTS

On the assumption that both FEA and lobular neoplasia (LN) derive from progenitor cells in the terminal ductal-lobular unit, we investigated the association between FEA and LN semiquantitatively in 111 excisional breast biopsy specimens which contained LN, but did not contain ductal carcinoma in situ (DCIS) or invasive carcinoma. Ninety-six cases (86.5%) revealed coexistence of LN and FEA (P < 0001). The distribution of LN was focal in 41 cases (37%), multifocal in 50 (45%) and extensive in 20 (18%) cases. FEA was identified as focal, multifocal and extensive in 29 (26%), 42 (38%) and 25 (23%) cases, respectively. Distribution patterns of LN and FEA showed no statistically significant correlation.

CONCLUSIONS

Due to the striking association between LN and FEA in our material, one may speculate that these two lesions are biologically related and that FEA is an early but non-obligate precursor lesion similar to LN. Based on this assumption, regular clinical and mammographic follow-up of patients with FEA would be prudent.

High frequency of coexistence of columnar cell lesions, lobular neoplasia, and low grade ductal carcinoma in situ with invasive tubular carcinoma and invasive lobular carcinoma

This study was undertaken to determine the morphologic features and frequency of putative precursor lesions involved in the development of some pure forms of special types and low grade breast carcinoma. We reviewed 147 successive tumor cases, comprising tubular carcinoma (TC); pure type (n=56) and mixed type (n=20), invasive lobular carcinoma (ILC); classic type (n=57), and tubulolobular carcinoma (TLC; n=14). The presence of preinvasive lesions including columnar cell lesions (CCLs), usual epithelial hyperplasia, ductal carcinoma in situ (DCIS), and lobular neoplasia (LN) was determined. Estrogen receptor and E-cadherin immunohistochemistry was performed. Ninety-five percent (95%) of pure TCs had associated CCLs with the majority showing flat epithelial atypia. Atypical ductal hyperplasia (ADH)/DCIS was present in 89% patients. Colocalization of CCL, ADH/DCIS, and TC was seen in 85% patients, all displaying the same cytologic-nuclear morphology in most cases. LN was seen in 16%. In ILC, 91% cases showed LN. CCL and ADH/DCIS were seen in 60% and 42% cases, respectively. E-cadherin was positive in TLC but reduced in TC and completely absent in ILC. In conclusion, our findings support the hypothesis that CCLs are associated with pure and mixed forms of TC, and that LN is involved in ILC development. Our observations suggest that these lesions represent family members of low grade precursor, in situ and invasive neoplastic lesions of the breast. Molecular studies are being performed to substantiate the hypothesis that tubular and lobular carcinomas have direct evolutionary links to CCLs and flat epithelial atypia.

Cytologic diagnosis of columnar-cell lesions of the breast

This study describes the cytologic features of breast columnar-cell lesions (CCLs) and determines whether these lesions can be diagnosed by fine-needle aspiration. We present ten cases of biopsy-proven CCL with prior fine-needle aspiration material and discuss the spectrum of changes, as well as features important in the cytologic distinction of CCL from diagnostic mimics. CCLs were characterized by flat sheets of cells with enlarged nuclei, distinct cell borders, and finely granular cytoplasm. Cytologic atypia ranged from minimal to severe, and many cases (8/10) exhibited a paucity of myoepithelial cells. CCL showed significant cytologic overlap with papillary neoplasms and well-differentiated adenocarcinomas. The prospective diagnosis of CCL cannot reliably be made by fine-needle aspiration. However, it is important to recognize the range of cytologic atypia that can be seen with CCL to avoid an overdiagnosis of malignancy.

Characterization of columnar cell lesions of the breast: immunophenotypic analysis of columnar alteration of lobules with prominent apical snouts and secretions

Columnar cell lesions of the breast are detected with increasing frequency in routine pathology practice, in part as a result of the widespread biopsy of nonpalpable breast abnormalities detected by screening mammography. Immunohistochemical investigation of the lesions in relation to the normal breast or to other breast pathologies is not well characterized, and the malignant potential of this spectrum of lesions has not been examined clinically. In this study, a cohort of 45 breast specimens containing columnar cell lesions, in particular, columnar alteration of lobules with prominent apical snouts and secretions (CAPSS), was investigated for expression of a series of breast tumor biomarkers. Using a semiquantitative immunohistochemical scoring system, up-regulation of estrogen, progesterone, and androgen receptors in CAPSS lesions to levels not significantly different from that in in situ or invasive breast tumors was identified. In four cases where CAPSS within a specimen lacked expression of a steroid hormone receptor, the coexisting in situ or invasive carcinoma also lacked expression of that receptor. In 81% of CAPSS lesions, E-cadherin immunostaining was reduced in isolated foci of cells or was decreased in intensity in all cells within the lesion. Quantitation of Ki-67 immunostaining demonstrated that proliferation of cells within CAPSS lesions was increased, compared with normal breast epithelium, but was lower than that detected in in situ or invasive cancers within the same specimens. Results of these analyses indicate that CAPSS shares immunophenotypic alterations with other premalignant lesions, the clinical implications of which may be investigated using established breast tumor biomarkers.

Flache epitheliale Atypie und andere Zylinderzellläsionen der Brust

Columnar cell lesions are being increasingly identified in specimens excised for mammographically suspect microcalcifications. The entity of flat epithelial neoplasia remains a challenge for surgical pathologists due to its uncertain biological and clinical significance, inconsistent nomenclature, lack of prognostic data and the often unobtrusive and easily overlooked histological findings. This review aims to summarize our experience and the currently available literature on this topic, and will lead to a better understanding of this lesion. Because of its putative role as a precursor lesion and its many similarities to atypical ductal hyperplasia or ductal carcinoma in situ, differentiation from these lesions on the one hand and from columnar cell lesions without atypia on the other, is of importance and should result in different therapeutic recommendations depending on its presence in excisional or core needle biopsies.

Interobserver reproducibility in the diagnosis of flat epithelial atypia of the breast

Columnar cell lesions (CCLs) of the breast with low-grade/monomorphic-type cytologic atypia are being identified increasingly in biopsies performed owing to mammographic microcalcifications. The WHO Working Group on the Pathology and Genetics of Tumours of the Breast recently introduced the term 'flat epithelial atypia' (FEA) for these lesions. However, the ability of pathologists to reproducibly diagnose FEA and to distinguish it from CCLs without atypia has not been previously evaluated. Eight pathologists with an interest in breast pathology participated in a study to address this issue. The study reference pathologist provided the other seven study pathologists with a Powerpoint tutorial that included written criteria for, and representative images of, FEA and CCLs without atypia (ie, columnar cell change and columnar cell hyperplasia). Following review of the tutorial, the study pathologists examined images in Powerpoint format from 30 CCLs and were instructed to categorize each as either 'FEA' or 'not atypical'. Overall agreement among the eight pathologists was 91.8% (95% CI, 84.0-96.9%), and the multi-rater kappa value was 0.83 (95% CI, 0.67-0.94), which is within the 'excellent agreement' range. Agreement was slightly better for determining absence of FEA (92.8%: 95% CI, 84.1-97.4%), than for determining its presence (90.4%: 95% CI, 79.9-96.7%). We conclude that the diagnosis of FEA and its distinction from CCLs without atypia is highly reproducible with the use of available diagnostic criteria.

Tubular carcinoma of the breast and associated intra-epithelial lesions: a comparative study with invasive low-grade ductal carcinomas

Ductal intra-epithelial lesions of the breast are associated with invasive neoplasms and comprise a large spectrum of histological patterns. We have examined 23 cases of pure tubular carcinomas (TCs) of the breast and 53 cases of invasive ductal low-grade carcinomas to determine the relationship and distribution of intra-epithelial lesions, mainly of ductal in situ carcinoma type, but including also lobular intra-epithelial neoplasia (LIN) in both entities. Eleven cases of TC showed flat epithelial atypia (FEA) (47.8%), and, in 14 and 6 cases, micropapillary and cribriform low-grade ductal carcinoma in situ (DCIS) were present (60.7 and 26.1%, respectively). On the opposite, in ductal grade I invasive carcinomas, the most frequent architectural pattern was low-grade DCIS growing in arcades in 26 cases (49%). While absent in TCs, low-grade DCIS of solid type was found in five (9.4%) cases of ductal invasive carcinomas, where FEA were present in seven (13.2%) cases. LIN lesions were present in four (17.4%) cases of TC, whereas they represented 7.5%, as reported by Carstens et al. (Am J Clin Pathol 58:231-238, 1972), of cases of low-grade carcinomas. These results suggest that invasive pure TC and low-grade ductal carcinomas of the breast are different lesions, and support the fact that TC, of low histopathological grade, is a particular distinct tumoural entity.

Flat epithelial atypia: concepts and controversies of an intraductal lesion of the breast

Image-guided biopsies of the breast play an integral role in the diagnostic evaluation of mammographically detected calcifications. Apart from cancer, on these biopsies we are increasingly recognising a hitherto poorly categorised group of benign to atypical entities collectively known as columnar cell lesions. A variant of this theme is flat epithelial atypia, a columnar lesion characterised by mildly atypical epithelial cells. There is emerging evidence to suggest that flat epithelial atypia may represent a precursor of or the earliest morphologically recognisable form of low-grade ductal carcinoma in situ. In addition, these lesions are often associated with tubular carcinomas and lobular neoplasia. This article reviews the current concepts and controversies surrounding flat epithelial atypia, with special emphasis on the biology, histological and clinical features. Potential diagnostic challenges faced by pathologists in the evaluation of these atypical columnar lesions are also discussed.

Assessment of lesions coexisting with various grades of ductal intraepithelial neoplasia of the breast

Ductal intraepithelial neoplasia (DIN) is descriptive of in situ breast lesions from usual ductal hyperplasia (UDH) to advanced ductal carcinoma in situ (DCIS). A total of 2628 cases of DIN diagnosed at the Armed Forces Institute of Pathology were separated based on their grade. These were assessed for the presence of invasive carcinoma (ductal or lobular) and lobular intraepithelial neoplasia (LIN) grades 1-3. The frequency of invasive cancer (ductal and lobular) appearing with DIN increased with increasing DIN grade from 2% in low-risk DIN (UDH) to 37% in DIN 2-3 (DCIS grades 2-3). The frequency of these invasive carcinomas, which were either lobular or displayed lobular features, however, decreased with increasing grade of DIN with a peak of 28% in DIN 1-flat type, (flat epithelial atypia) to a low of 2% in DIN 3. Likewise, the frequency of LIN appearing with DIN decreased as the grade of DIN increased, with a peak of 26% in DIN 1-flat type to a low of 9% in DIN 3. Lower-grade LIN 1 comprised 14% of the LIN in low-risk DIN cases, but only 4% of the LIN seen in DIN 3 cases. Conversely, higher-grade LIN 3 comprised only 6% of the LIN seen in low-risk DIN cases, while accounting for 15% of the LIN in DIN 3 cases. The frequency of invasive carcinoma in DIN 1 ranged from 4% in quantitatively limited DIN 1 less than or equal to 2 mm (atypical ductal hyperplasia) to 27% among the more abundant DIN 1 greater than 2 mm (DCIS grade 1). The frequency of LIN associated with DIN 1 less than or equal to 2 mm was 13.4%, and the frequency of LIN associated with DIN 1 greater than 2 mm was 16.6% when there was no DIN 1-flat type present. However, the frequency of the LIN seen in combination with DIN 1-flat type was reduced by 50% as the quantity of DIN exceeded 2 mm. Based on this retrospective analysis of DIN, we noted that: (1) invasive carcinoma is most frequently associated with the higher grades of DIN; (2) the grade of LIN parallels the grade of coexisting DIN; (3) a relationship exists between DIN 1-flat type and the occurrence of LIN and (4) this relationship in association with DIN less than or equal to 2 mm is not maintained in DIN greater than 2 mm.

Columnar cell lesions: current classification and controversies

"Columnar cell lesions" is a general descriptive term referring to disparate lesions having in common cells with a columnar configuration but not necessarily identical histologic or biologic characteristics. Within this large category, a group of lesions having in common a population of atypical cells (frequently columnar shaped) is emerging as early neoplastic lesions. This article reviews the histological features, differential diagnosis, associated lesions, biologic potential, clinical significance, and management of atypical columnar cell lesions.

Columnar cell lesions of the breast

Columnar cell lesions of the breast represent a spectrum of lesions which have in common the presence of columnar epithelial cells lining variably dilated terminal duct lobular units, ranging from those that show little or no cytologic or architectural atypia to those that show sufficient cytologic and architectural features to warrant a diagnosis of atypical ductal hyperplasia or ductal carcinoma in situ. Recent studies have begun to provide insights into the biological nature and clinical significance of these lesions. In this article, we review the current state of knowledge and propose a simplified scheme for their classification.