Columnar cell lesions of the breast: pathological features and clinical significance

Upgrade Rate of Flat Epithelial Atypia Diagnosed at Stereotactic Core Needle Biopsy of Microcalcifications: Is Excisional Biopsy Indicated?

OBJECTIVE

Whether the optimal management of pure flat epithelial atypia (FEA) found on core needle biopsy (CNB) specimens is surgical excision or imaging follow-up remains controversial. This study aimed to determine the upgrade rate to ductal carcinoma in situ (DCIS), invasive carcinoma or a high-risk lesion (atypical ductal hyperplasia, atypical lobular hyperplasia, or lobular carcinoma in situ), and it explored the relationship between a family history of breast cancer and the risk of upgrade.

METHODS

Cases with pure FEA found on stereotactic CNB of microcalcifications between March 2011 to December 2017 were followed by excisional biopsy or periodic imaging. The proportion of cases upgraded to a high-risk lesion and the odds of upgrade as related to a family history of breast cancer were determined with 95% confidence intervals (CIs).

RESULTS

We identified 622 cases of pure FEA; 101 (16.2%) underwent surgical excision and 269 (43.2%) had imaging follow-up of ≥ 24 months. There were no upgrades to DCIS or invasive cancer in any of these 370 individuals (0%), and 4.6% (17/370; 95% CI: 2.9%-7.2%) were upgraded to a high-risk lesion. There was a nonstatistically significant trend between family history and upgrade to high-risk lesion (odds ratio 1.72 [95% CI: 0.65%-4.57%]).

CONCLUSION

In our study, the upgrade rate of pure FEA to malignancy was 0%. We suggest that regular imaging follow-up is an appropriate alternative to surgery. Because of potential differences in biopsy techniques and pathologist interpretation of the primary biopsy, individual institutions should audit their own results prior to altering their management of FEA.

Multicolor immunofluorescence reveals that p63- and/or K5-positive progenitor cells contribute to normal breast epithelium and usual ductal hyperplasia but not to low-grade intraepithelial neoplasia of the breast

We contend that knowledge about the cellular composition of normal breast epithelium is a prerequisite for understanding proliferative breast disease. Against this background, we used multicolor immunofluorescence to study normal breast epithelium and two types of intraepithelial proliferative breast lesion for expression of the p63, basal keratin K5, glandular keratin K8/18, SMA, ER-alpha, and Ki67. We studied eight normal breast epithelium samples, 12 cases of usual ductal hyperplasia, and 33 cases of low-grade intraepithelial neoplasia (9 flat epithelial atypia, 14 low-grade ductal carcinoma in situ and 10 cases of lobular neoplasia). Usual ductal hyperplasia showed striking similarity to normal luminal breast epithelium including p63+ and/or K5+ luminal progenitor cells and the full spectrum of luminal progeny cells. In normal breast epithelium and usual ductal hyperplasia, expression of ER-alpha was associated with lack of expression of the proliferation antigen Ki67. In contrast, we found in both types of low-grade intraepithelial neoplasia robust expression of keratin K8/18 and a positive association between ER-alpha and Ki67 expression. However, these lesions were consistently negative for p63 and/or K5. Our observational study supports the view that usual ductal hyperplasia and low-grade intraepithelial neoplasia are different entities rather than part of a spectrum of the same disease. We propose a new operational model of cell differentiation that may serve to better understand correlations between normal breast epithelium and proliferative breast diseases. From our data we conclude that p63+ and/or K5+ progenitor cells contribute to maintenance of normal epithelium and usual ductal hyperplasia, but not to low-grade intraepithelial neoplasia of the breast.

Digital mammography: more microcalcifications, more columnar cell lesions without atypia

The incidence of columnar cell lesions in breast core needle biopsies since full-field digital mammography in comparison with screen-filmed mammography was analyzed. As tiny microcalcifications characterize columnar cell lesions at mammography, we hypothesized that more columnar cell lesions are diagnosed since full-field digital mammography due to its higher sensitivity for microcalcifications. In all, 3437 breast core needle biopsies performed in three hospitals and resulting from in total 55 159 mammographies were revised: 1424 taken in the screen-filmed mammography and 2013 in the full-field digital mammography period. Between the screen-filmed mammography and full-field digital mammography periods, we compared the proportion of mammographies that led to core needle biopsies, the mammographic indication for core needle biopsies (density, microcalcifications, or both) and the proportion of columnar cell lesions with or without atypia. The columnar cell lesions were graded according to Schnitt, and we included atypical ductal hyperplasia arising in the context of columnar cell lesions. Proportions were compared using χ(2) tests and prevalence ratios were adjusted for age and hospital. We found that more core needle biopsies per mammogram were taken in the full-field digital mammography period (7.6%) compared with the screen-filmed mammography period (5.0%, P<0.0001). Microcalcifications were more often diagnosed with full-field digital mammography than with screen-filmed mammography (adjusted prevalence ratio: 1.14, confidence interval 95%: 1.01-1.28). Core needle biopsies from the full-field digital mammography era showed more columnar cell lesions (10.8%) than those from the screen-filmed mammography era (4.9%; adjusted prevalence ratio: 1.93, confidence interval 95%: 1.48-2.51), particularly due to more columnar cell lesions without atypia (8.2% respectively 2.8%) while the proportion of columnar cell lesions with atypia remained nearly constant (2.0 vs 2.6%). In conclusion, since the implementation of full-field digital mammography, more microcalcifications are seen at mammography, more often resulting in core needle biopsies, which especially yields more columnar cell lesions without atypia.

Columnar cell lesions of the breast: an update and significance on core biopsy

Columnar cell lesions of the breast refer to the morphological spectrum of alterations of the epithelial lining of variably dilated acini of the terminal duct lobular unit (TDLU), often related to secretions and calcifications. After decades of varied terminologies, the term of 'flat epithelial atypia' by the World Health Organization (WHO) consensus group encompasses the part of the spectrum where columnar cell change or columnar cell hyperplasia acquires low grade cytological atypia, merging with atypical ductal hyperplasia and low grade ductal carcinoma in situ. Its association with low grade invasive carcinoma and lobular neoplasia, whether by proximity to these lesions, or by similar molecular expressions, has prompted greater scrutiny into its clinical significance. Although recent literature attempts to refine the term 'flat epithelial atypia', the applicability of its morphological criteria in routine diagnostic practice remains to be seen, and interobserver variability is highly possible. This poses even greater challenges especially in limited samples of breast tissue, such as in core biopsies, for pre-operative decision-making. The purpose of this review is to elucidate evolving clinical and diagnostically relevant principles that surround and influence the significance of this still controversial entity, especially when discovered on core biopsy in the initial phase of breast diagnosis and management.

Columnar cell lesions of the breast - significant or not?

Columnar cell lesions (CCL) of the breast range from the innocuous CAPSS (Columnar alteration with prominent apical snouts and secretions) to DCIS. Their precancerous potential poses diagnostic and therapeutic riddles, especially for those with mammographic microcalcifications.

AIM

To document the incidence of columnar cell lesions in the breast, to study their morphologic spectrum and to study the significance of their association with benign and malignant breast lesions.

MATERIAL AND METHODS

We studies 100 consecutive breast specimens. These specimens included biopsies, lumpectomies and mastectomies. Columnar cell lesions were classified as per Schnitt criteria. Associated lesions in the adjacent tissue were also studied.

RESULTS

Of the 100 samples (43 malignant and 57 benign), 37 cases showed CCL: CAPSS 23, columnar cell hyperplasia-11 and Columnar cell hyperplasia with atypia-3. The commonest associated lesion was fibrocystic change (n=54). Their incidence in benign and malignant lesions was 42% and 30% respectively, with no statistical significance in the difference. Lesions with atypia were seen only in malignant cases.

CONCLUSION

Columnar cell lesions are common, and often overlooked. These lesions are seen in association with both benign and malignant breast lesions. It is only the presence of atypia in CCL that warrants a special mention and necessitates follow up, and resection if indicated.