Columnar Cell Lesions and Flat Epithelial Atypia of the Breast

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.

Management of flat epithelial atypia on breast core biopsy may be individualized based on correlation with imaging studies

Flat epithelial atypia of the breast commonly co-exists with atypical ductal hyperplasia, lobular neoplasia, and indolent forms of invasive carcinomas such as tubular carcinoma. Most patients with pure flat epithelial atypia on core biopsy undergo surgical excision to evaluate for carcinoma in the adjacent breast tissue. Studies to date have reported varying upgrade rates with most recommending follow-up excision. These studies have often lacked detailed radiographic correlation, central review by breast pathologists and information regarding the biology of the carcinomas identified upon excision. In this study, we report the frequency of upgrade to invasive carcinoma or ductal carcinoma in situ in excision specimens following a diagnosis of pure flat epithelial atypia on core biopsy. Radiographic correlation is performed for each case and grade/receptor status of detected carcinomas is reported. Seventy-three (73) core biopsies containing pure flat epithelial atypia were identified from our files, meeting inclusion criteria for the study. In the subsequent excision biopsies, five (7%) cases contained invasive carcinoma or ductal carcinoma in situ and seventeen (23%) contained atypical ductal hyperplasia or lobular neoplasia. All of the ductal carcinoma in situ cases with estrogen receptor results were estrogen receptor positive and intermediate grade. The invasive tumors were small (pT1a) hormone receptor-positive, HER2-negative, low-grade invasive ductal or tubular carcinomas with negative sentinel lymph-node biopsies. No upgrades were identified in the 14 patients who had all of their calcifications removed by the stereotactic core biopsy. Our rate of upgrade to carcinoma, once cases with discordant imaging are excluded, is at the lower end of the range reported in the literature. Given the low upgrade rate and indolent nature of the carcinomas associated with flat epithelial atypia, case management may be individualized based on clinical and radiographic findings. Excision may not be necessary for patients without remaining calcifications following core biopsy.

Is there 'progression through grade' in ductal invasive breast cancer?

Recent molecular data pointed towards the possibility of a stepwise dedifferentiation in a subgroup of invasive breast cancer (BC) cases. It was hypothesized that oestrogen receptor positive (ER+) grade 3 (G3) ductal invasive BCs are the end stage of a dedifferentiation process of luminal BC. A progression of luminal A towards luminal B BCs associated with a 'progression through grade' and an increased cell proliferation seemed the obvious explanation. In order to verify this hypothesis on a morphological and immunohistochemical level, we investigated 865 invasive BC cases. All cases were reviewed for the presence of intratumoural heterogeneity in grade of the invasive cancer and the presence of associated ductal carcinoma in situ (DCIS). With the use of tissue microarrays, the molecular subtype was determined and correlated with clinico-pathological features. In addition, all cases were stained for p21, p27, Ki-67, Cyclin D1, bcl-2, p53, and p16 and the results subjected to a biomathematical dependency analysis. The frequency of ER-positivity decreased with tumour size. The frequency of luminal A BC decreased as well, whereas the number of luminal B BCs remained constant. A gradual increase of the frequency of basal-like, HER2-driven and non-expressor BCs with tumour size was seen. In only 1 out of 865 BC cases, both a G1 and a G3 invasive cancer component was seen within the same BC. In two cases, a ductal invasive G1 carcinoma was associated with a poorly-differentiated DCIS. The frequency of columnar cell lesions was evenly distributed over ER+ and ER- ductal invasive G3 carcinomas. The biomathematical analysis gave striking hints against an obligate progression of BC trough grade. In conclusion, our results show that a morphological recognizable striking 'progression through grade' at least in its extreme form from G1 towards G3 is a very rare event in the natural course of invasive BC, including luminal BC.

Columnar cell lesions of the breast: mammographic findings with histopathologic correlation

Because of advances in mammography and a concomitant rise in the number of breast biopsies being performed for mammographically detected abnormalities, increasing numbers of columnar cell lesions (CCLs) are being described by pathologists. However, these lesions can be challenging to manage, since their classification has changed over time and only limited research has been conducted regarding their clinical significance. CCLs may be characterized by a single layer of columnar cells (columnar cell change [CCC]), multiple layers with stratification and apical tufting (columnar cell hyperplasia [CCH]), or monomorphic cells with cytologic atypia (flat epithelial atypia [FEA]). The differentiation between CCC, CCH, and FEA is clinically significant: CCC and CCH are considered benign lesions, whereas FEA can be associated with, and even a precursor to, low-grade ductal carcinoma in situ and atypical ductal hyperplasia. Therefore, the identification of FEA at core biopsy should prompt excision of the remaining portion of the lesion.

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.