Relationship between columnar cell changes and low-grade carcinoma in situ of the breast—a cytogenetic study

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.

Blunt duct adenosis: a separate entity from columnar cell lesions?

Blunt duct adenosis (BDA) is a breast lesion first described by Foote and Stewart in 1945 as a proliferative benign lesion of the terminal duct lobular unit. Throughout recent decades, further literature descriptions of BDA have been confusing. Some consider BDA to be a separate entity, some a growth pattern of columnar cell changes. The WHO 2012 considered BDA and columnar cell changes to be synonyms, while columnar cell lesions, especially those with atypia, are part of a spectrum of early precursors of the low nuclear grade breast neoplasia family. In the updated WHO 2019 version, BDA is mentioned as 'not recommended' terminology for columnar cell lesions without further discussing it, leaving the question open if BDA should be considered a separate entity.Good diagnostic criteria for BDA have however largely been lacking, and its biological background has not yet been unravelled. In this paper, we point out that BDA is mainly associated with benign breast lesions and not with other recognised precursor lesions. Further, 16q loss, which is the hallmark molecular event in the low nuclear grade breast neoplasia family, is lacking in BDA. We therefore hypothesise that BDA may not be a true precursor lesion but a benign polyclonal lesion, and propose morphological diagnostic criteria to better differentiate it from columnar cell lesions.

Role of columnar cell lesions in breast carcinogenesis: analysis of chromosome 16 copy number changes by multiplex ligation-dependent probe amplification

Columnar cell lesions have been proposed as precursor lesions of low-grade breast cancer. The molecular characteristic of low-grade breast neoplasia is whole-arm loss of chromosome 16q. Copy number changes of 6 genes on 16p and 20 genes on 16q were analysed by multiplex ligation-dependent probe amplification in 165 lesions of 103 patients. Twenty-three columnar cell lesions and 19 atypical ducal hyperplasia lesions arising in columnar cell lesions were included, as well as cases of usual ductal hyperplasia, blunt duct adenosis, ductal carcinoma in situ, lobular neoplasia and invasive carcinoma. Usual ductal hyperplasia and blunt duct adenosis lacked whole-arm losses of 16q. In contrast, columnar cell lesions without atypia, columnar cell lesions with atypia, atypical ductal hyperplasia, low-grade ductal carcinoma in situ and low-grade invasive carcinomas increasingly harboured whole-arm losses of 16q (17%, 27%, 47% and 57%, respectively). However, no recurrent losses in specific genes could be identified. In several patients, columnar cell lesions and atypical ductal hyperplasia harboured similar losses as related ductal carcinoma in situ or invasive carcinomas within the same breast. There were indications for 16q breakpoints near the centromere. Whole-arm gains on 16p were relatively scarce and there was no relation between whole-arm gains of 16p and progression of lesions of the low-grade breast neoplasia family. In conclusion, columnar cell lesions (with and without atypia) often harbour whole-arm losses of 16q, which underlines their role as precursors in low-grade breast carcinogenesis, in contrast with usual ductal hyperplasia and blunt duct adenosis. However, no recurrent losses in specific genes could be identified, pointing to minor events in multiple tumour suppressor genes rather than major events in a single 16q gene contributing to low-grade breast carcinogenesis.

Mucinous precursor lesions of mucinous carcinoma in breast: Incidence and histopathologic features

Objectives Columnar cell lesion (CCL), atypical ductal hyperplasia (ADH) and ductal carcinoma in situ (DCIS) may be premalignant lesion of mammary invasive carcinoma. A few recent investigators reported that the precursor lesions exhibited mucin production and they might be potential precursor lesion for mucinous carcinoma (mCA). This study aims to investigate the incidence and histopathologic characteristics of mucinous precursor lesions, including mucinous DCIS (mDCIS) and mucinous CCL (mCCL). Methods We retrospectively analyzed invasive carcinomas with mucin. Cases were grouped into three subgroups: pure mCA, mixed mCA, and invasive carcinoma of no special type with mucin production (IC of NST-m). Precursor lesions were evaluated with PAS and alcian blue staining. Results Total 27 cases of invasive carcinoma with mucin were analysed and classified as 18 pure mCA, 7 mixed mCA, and 2 IC of NST-m. mDCISs were found in 12 pure mCA, 4 mixed mCA and 2 IC of NST-m. mCCLs were found in 7 pure mCA and 2 mixed mCA. Majority of mucin was identified in both cytoplasm and ductal lumen, while some tumors exhibited only cytoplasmic mucin. We also observed three patterns of mDCIS classifiable by location of mucin and architecture of tumor cells. Conclusions Cytoplasmic mucin suggested that mucinous feature of precursor lesions in the vicinity of mCA might not be a passive morphologic finding but be involved in development of mCA.