Epithelial atypia in biopsies performed for microcalcifications. Practical considerations about 2,833 serially sectioned surgical biopsies with a long follow-up
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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.
KeywordsBreast Epithelial atypia Lobular neoplasia Atypical ductal hyperplasia Cancer
Breast biopsies for infraclinical lesions are more frequent with mammographic screening programs, but the distribution of the corresponding histological lesions and their associations are still imprecise. Difficulties encountered in following up patients without cancer account for the fact that the clinical significance of certain non-malignant lesions and the management of patients are still debated. Moreover, the problem of surgical biopsy sampling has never been fully investigated and has added additional confusion in appreciating the distribution and clinical significance of such lesions. In 1981, breast epithelial atypia were hardly mentioned and not clearly defined in the World Health Organization/International Union Against Cancer (WHO/UICC) histologic classification of breast tumors . The histologic classification of noncancerous lesions has been mainly based on studies analyzing for each lesion the associated risk of subsequent cancer. These studies were initiated by the survival studies of Dupont and Page [15, 46] based on lesions discovered by palpation before the era of mammography. Thereafter, further studies [6, 9, 17, 24, 31, 51, 62, 67] substantiated these results, which were ratified in 2003 by the new American Joint Committee on Cancer (AJCC)/UICC classification of breast tumors . Schematically, this classification differentiates benign epithelial lesions (usual ductal hyperplasia and other lesions) from atypical lesions of ductal or lobular type. Although this historical classification is challenged by a new classification , it remains the most widely used in practice. Interestingly, the occurrence of epithelial atypia was low in Page’s study  and has increased with mammographic screening programs [60, 66] and with the development of percutaneous large core needle biopsy (CNB) methods using stereotactic mammography or ultrasound guidance. At present, CNB is frequently used for the initial evaluation of clinically occult breast lesions, thus generating dilemma for the subsequent management of certain noncancerous lesions. At our institution, surgical biopsies (SB) have always been managed in the same way, and most patients with atypical and malignant lesions have been followed. The objectives of our work were to analyze the occurrence of epithelial atypia and their association with a concomitant cancer in a large series of SB performed for microcalcifications without a palpable tumor and to assess the subsequent cancer probability in the group of patients with an initial diagnosis of epithelial atypia. Finally, we provide some practical considerations for the management of patients with epithelial atypia in this era of mammographic screening and CNB.
Materials and methods
Selection of patients
At Institut Bergonié, from January 1975 to December 2002, 3,166 breast biopsies for diagnostic purposes, 2,833 SB and 333 CNB, were performed for microcalcifications without any palpable mass in 2,708 patients (mean age 51.8 years, range 19.7–81 years). Among them, 248 (9%) had several biopsies in the same or contralateral breast. Since 1998, microcalcifications have been classified according to the classifications of the American College of Radiology . SB for diagnostic purposes were defined before 1998 by the absence of a preoperative diagnosis based on the clinical–mammographic–cytologic triplet and by the absence of a positive frozen section and, since 1998, by the presence of epithelial atypia on CNB. Excluded from this study were 132 cancers and 139 non-atypical benign lesions diagnosed on CNB as well as 49 re-excisions performed elsewhere than in our center. Thus, 2,833 SB in 2,375 patients were available for analysis, among which 13 corresponded to re-excision after a CNB with epithelial atypia. Since 1989, needle localization, intraoperative specimen radiography, and post-excisional biopsy mammography have been performed in most cases.
Surgical biopsies and tissue sampling: serial macroscopic sectioning
SB was removed in one fragment and measured more than 3 cm in 94% of the cases (mean size 60 mm, 5–250 mm). For SB margin assessment, either the surface of the specimen was inked or the surgeon during the same operation removed additional tissue in the remaining cavity after excision of the specimen (surgical margins). After fixation in Holland Bouin, SB and margin specimens were serially sectioned in their entirety into numbered slices every 2 mm . In most cases (89%), careful macroscopic examination of the specimen failed to reveal any lesion. Each numbered slice was put in as many numbered separate cassettes as necessary and paraffin-embedded in sequence. The median number of blocks per SB was 26 (from 2 to 180) and 8 (from 1 to 44) for surgical margins. Each block was examined on one hematoxylin–eosin–safran stained slide.
Classification of lesions and review of slides
Since 1975, all patients have been prospectively included in our clinical, histologic, and biologic database by senior pathologists (IM, GMG, IS, JMC). For each SB and each lesion, we prospectively entered in our pathologic database morphological descriptive criteria by using 65 pathological items for noncancerous lesions and 181 for cancers. Definitions and terminologies given in the literature were used to report columnar cell lesions (CCL), non-atypical ductal hyperplasia, atypical ductal hyperplasia, ductal carcinoma in situ (DCIS), and lobular carcinoma in situ (LCIS) [1, 4, 7, 10, 17, 19, 21, 22, 23, 24, 25, 26, 27, 28, 38, 43, 44, 45, 47, 49, 50, 56, 59, 61, 69, 72, 74, 75]. The interest of our database was to collect morphological descriptive criteria of nearly all the breast lesions without labeling them. In fact, labels and definitions of breast lesions have varied throughout the past 30 years, while neither lesions nor their corresponding descriptive criteria (i.e., size, type, architecture, cellular and nuclear features, etc...) have changed. The only changes during this period were the definitions and/or the names given to these lesions. As we have listed for each lesion all the corresponding descriptive criteria among the 236 available items, we have been able to reclassify each lesion according to the “new” criteria recommended by referent authorities for a new definition, by selecting in our database the “new” correspondent descriptive criteria corresponding to this new definition. Consequently, this provided a homogeneous approach to the pathological lesions at the time of our study. For example, low-grade DCIS ≤ 2 mm have been reclassified as atypical ductal hyperplasia/ductal intraepithelial neoplasia (ADH/DIN) 1B (n = 30) according to the new AJCC/UICC classification of breast tumors , and lesions that we used to term before 1997  as clinging carcinoma of the monomorphic type  have been reclassified as flat epithelial atypia (FEA)/DIN 1A or columnar cell change (CCC) with atypia (n = 84) . About half of these 114 cases have been systematically reviewed by one (IM) or two senior pathologists (IM and GMG or IS), and there was a complete concordance between the second review and the initial descriptive criteria listed in the database. Similarly, lesions that we used to name LCIS before 1997 have been renamed lobular neoplasia (LN) since 1997, corresponding either to atypical lobular hyperplasia (ALH) or to LCIS. On the contrary, all the cases with micropapillary lesions were reviewed (n = 155) because there was no item corresponding to precise descriptive criteria of micropapillations (number, topography around the duct, type).
Atypical ductal hyperplasia: definition and sizing
Among the group of ADH/DIN 1B, we individualized two morphologic types of ADH. Neither had any high-grade cytological atypia or necrosis.
FEA were present either as a single lesion or in association with ADH in the same TDLU and since 1997 have been included in the ADH group. The distinction of FEA from columnar change without atypia was based on the criteria given by the WHO for the definition of FEA. Furthermore, columnar change without atypia was characterized by one or two layers of columnar cells without nuclear atypia, i.e., no increase in the nuclear/cytoplasmic ratio, no prominent nucleoli. Nevertheless, some cases of columnar change with progesterone impregnation, especially in the second part of the cycle, might display a lobular distension with a secretory material and large nuclei with prominent nucleoli. In such cases, myoepithelial cells displayed the same alterations with clarified cytoplasms, thus facilitating the diagnosis. The distinction of ADH mimicking DCIS from usual hyperplasia (UDH) was based on morphological criteria. Architectural pattern and cytologic criteria of usual ductal hyperplasia were easy to identify in most cases. UDH corresponded to a proliferation of epithelial cells in solid or fenestrated areas without any polarization of surrounding cells. Cells were haphazardly arranged with overlapping nuclei or were parallel with characteristic streamings. They were elongated or pseudo epithelioid, but there was no columnar metaplasia. Cytoplasms were more or less abundant with indistinct borders. Nuclei had irregular size and shape and sometimes contained a prominent eosinophilic inclusion. In some rare cases, immunohistochemical staining with cytokeratin 5/6  was used and was negative in ADH mimicking DCIS and strongly positive in UDH. In some lesions, differential diagnosis between ADH and low-grade DCIS was all the more difficult because there were intermediate and intricated morphological aspects in the same TDLU. In practice, diagnosis of micropapillary lesions was often difficult. Extensive micropapillary lesions were classified as DCIS when quantitative and qualitative criteria were simultaneously present, i.e., lesion sizing more than 2 mm corresponding to micropapillations with a tight base over the entire periphery of the ducts. Additional sections could be useful for demonstrating more or less qualitative or quantitative diagnostic criteria. When malignancy remained equivocal, the case was classified as ADH. When a concomitant cancer was diagnosed, histologic size was assessed, and in DCIS, the percentage of blocks with cancer (“positive blocks”) was specified . Presence and topography of microcalcifications were also assessed. Lastly, when FEA and/or “mimicking” DCIS foci were found on excision margins of a SB with DCIS, a further surgical resection was not performed.
Follow-up of patients with epithelial atypia as a single lesion
There were 443 patients with epithelial atypia in one or several SB, without any previous or synchronous carcinoma in the same or contralateral breast and treated by biopsy alone (median follow-up 160 months, 7 to 315). Only 28/443 (6%) were lost to follow-up. Among the 415 other patients, 180 were monitored at our institute and 235 outside by correspondent specialists working in close relationship with our institute. All patients received a clinical examination and mammography once a year. When a new biopsy was necessary, it was performed at our institute.
Comparison of clinical and histologic characteristics was conducted by using the chi-square test. For women with epithelial atypia, the probability of developing in situ or invasive cancer was calculated from the date of the first biopsy to the earliest event: breast cancer (ipsi- or contralateral), death, or last contact (last consultation for the group monitored at our institute and checkpoint date, i.e., 1 March 2004, for the others). Probabilities were calculated according to the Kaplan–Meier method (SPSSv11).
Occurrence of epithelial atypia in the 2,833 surgical biopsies
Epithelial atypia were recorded in 971/2,833 SB (34%). They were found with and without a concomitant cancer in 301/971 (31%) and 670/971 (69%) of the cases, respectively. Thus, isolated epithelial atypia were found in 23% of the cases (670 out of the 2,833 SB). Calcifications were present at histologic examination in 98.6% of SB with cancer and were located in benign, cancerous, and both lesions in 10, 39, and 51% of the cases, respectively. In several cases, cancerous foci without any microcalcifications were located at points distant from those with calcifications detected by needle localization.
Types of epithelial atypia
Among the 971 SB with epithelial atypia, there were 101 SB with FEA as a single lesion (11%), 342 (35%) with ADH, 223 (23%) with LN, and 305 (31%) with ADH and LN. Thus, ADH was encountered in 647/971 SB (66%).
Types of cancers associated with epithelial atypia
Types of concomitant cancers (n = 301) in the 971 surgical biopsies with epithelial atypia
FEA (n = 101)
ADH (n = 342)
LN (n = 223)
ADH + LN (n = 305)
No. of cases (%)
No. of cases (%)
No. of cases (%)
No. of cases (%)
Cancers without epithelial atypia (malignancy alone)
There were 821 malignant SB without epithelial atypia [590 micro-invasive carcinomas, 206 infiltrating ductal carcinomas (IDC), and 25 infiltrating lobular carcinomas (ILC)].
Subsequent cancer in patients with an initial diagnosis of epithelial atypia as a single lesion
Application of the WHO classification: practical considerations
Terminologies used for intraductal proliferative lesions with low-grade cytologic atypia, so-called atypical columnar cell lesions
Spectrum of lesions
1, 3–5 Layers
Cribriform spaces and their variants
No or rare arcades and micropapillary formations
Cohesive micropapillary tufts with a broad base
Non-cohesive micropapillary tufts with a tight base
Flat epithelial atypia/DIN 1A
ADH/DIN 1B ≤ 2 mm; or in two spaces
Columnar cell hyperplasia with atypia
ADH if not extensive
DCIS if extensive
Columnar cell change (CCC) with cytologic atypia
Complex structures with architectural and cytologic atypia
Columnar cell lesions + ADH
Microscopic focus of DCIS
Ex-clinging carcinoma of monomorphic type
ADH “mimicking” DCIS
ADH corresponding to “mini” DCIS ≤ 2 mm
CCC with cytologic atypia
CCH with architectural atypia
CCH with architectural atypia
CCH with cytologic atypia
Measured: ≤3 mm
Occurrence of epithelial atypia and their association with a concomitant cancer: practical considerations
In our study, the proportion of epithelial atypia is high (23%), a result difficult to compare to others in the literature, as the methodologies used by teams are different. In the Page and Dupont case-control studies [15, 46], ADH and ALH were found in 2.1 and 1.6% of the cases, respectively. In mammographic screening programs, epithelial atypia and cancers increase as the number of biopsies performed for microcalcifications increases, especially as ACR4/ACR5 lesions are more often excised than ACR3. However, as underlined by Page , “the most direct relationship of epithelial atypia incidence is to slide rating.” The number of slides per SB in our study (median 26) was higher than in the other studies on benign breast lesions: 1–5 in 93% of the cases in the study of Page et al.  (n = 283), 3 (range 1–25, n = 674) in the study of Shaaban et al. , and a mean of 1.6 slides per cm of tissue (n = 199) in the study of Tavassoli and Norris . In a recent study conducted in the south west of France in women aged between 50 and 75 with mammographically detected non-palpable breast lesions, a similar proportion of atypical lesions were found when biopsies were serially sectioned . Furthermore, this high slide rating allowed the detection of small concomitant cancers in the vicinity of epithelial atypia in 31% of our cases, with a skew towards low-grade lesions (high proportions of DCIS and low-grade invasive carcinomas, especially tubular carcinomas). Our results strengthen the hypothesis that FEA and ADH are risk markers of low-grade cancers. This has been confirmed by the study of Simpson et al.  on molecular genetic profiles of CCL. In some of them, there are both a morphological and a molecular continuum in the degree of proliferation and atypia, supporting the hypothesis that “CCL are a non-obligate, intermediary step in the development of some forms of low grade in situ and invasive carcinoma.” The association of epithelial atypia with a concomitant cancer in nearly one third of the cases in our study parallels previous findings concerning the frequency of cancers found in SB performed for atypia in CNB. Thus, approximately 30% [20, 29] and 15 to 21% [5, 8, 14, 18, 35, 45, 53, 63, 76] of excisions after CNB with ADH and LN, respectively, were proven to have cancer. Consequently, excision is recommended  for all patients in whom ADH is identified on CNB and may be justified in patients with FEA, as they are included in the spectrum of ACCL. Excision remains a controversial issue in patients with LN. Some authors have advocated it [3, 18, 33, 63], while others have rebutted it , especially when LN is an incidental non-extensive finding  with no radiologic–pathologic discordance  and without any synchronous mass lesion . SB corresponding to re-excision should be processed in its entirety by serial macroscopic sectioning [32, 65]. When pathologic examination is exclusively focused on mammographic calcifications, the risk is to underestimate the DCIS size/extension because cancerous foci without any calcification (10% in our study vs 6% in Owing’study)  may be located at points distant from those with benign breast tissue containing calcifications.
Subsequent cancer after an initial diagnostic of epithelial atypia as a single lesion: practical considerations
In the literature, 4 to 22% (average interval 8.3 years follow-up) [6, 42, 67] and 15 to 20% [16, 30, 56] of patients developed invasive carcinomas after a diagnosis of ADH and LN, respectively. The risk of developing cancer increases with extended follow-up, but many cancers after a diagnosis of LN have a good prognosis and a low mortality . These results are difficult to compare to ours because the methodologies are different. The low probabilities of subsequent invasive cancer in our study could be due to the high slide rating, allowing the detection of small concomitant cancer that might have been missed with a low slide rating and inadequate patient management [11, 54].
In conclusion, when epithelial atypia are present, they are associated in nearly one third of the cases with a concomitant close cancer and are found as isolated lesions in nearly 23% of SB performed for microcalcifications. In practice, ADH should be more clearly defined with simple guidelines for measuring lesions. When malignancy remains equivocal and/or when sizing is difficult, it is better to classify the lesion as ADH. Epithelial atypia could be more a “risk factor” of a concomitant geographically small close cancer than a risk marker for a subsequent cancer, as they form part of a spectrum of lesions .