Navigating Atypical Breast Lesions: When to Worry and What to Do
"Understanding Flat Epithelial Atypia, Radial Scars, and Intraductal Papillomas for Informed Decisions About Breast Health"
High-risk breast lesions, identified through histologic epithelial abnormalities, elevate the risk of breast cancer due to potential underestimation during core needle biopsies or increased long-term risk. The rising use of screening mammography has led to more frequent diagnoses of these lesions through percutaneous image-guided biopsies.
For surgeons, understanding which lesions necessitate surgical excision to rule out associated malignancies is crucial. In the absence of concurrent malignancy, a high-risk lesion represents a histologic finding linked to an elevated breast cancer risk. Atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH), and lobular carcinoma in situ (LCIS) are well-known examples, with extensive research dedicated to them.
Beyond these, other challenging high-risk lesions include flat epithelial atypia (FEA), radial scars, and papillary lesions. This article reviews these latter high-risk lesions, providing clinical management recommendations to empower informed decisions about breast health.
Risk and Management Uncertainty
Radial scars (RS) and flat epithelial atypia (FEA) are benign breast lesions found on core needle biopsies, and most are still being excised even as observation becomes more common. A 2025 review reports that RS without atypia has a 0–9% upgrade rate to malignancy, though the supplied summary does not give a corresponding figure for FEA. FEA is described as a benign proliferative lesion with columnar cell changes and cytologic atypia, often called an atypical or high-risk lesion. A 2024 systematic review identifies ADH, ALH, LCIS, and FEA as lesions associated with increased subsequent breast cancer risk, while noting that long-term risk had not yet been synthesized.
Diagnosis and Management Challenges
ADH, ALH, and FEA are common lesions detected mainly through mammographic screening and are considered risk lesions as well as non-obligate precursors of low-grade in-situ carcinoma. The 2026 multisociety guideline effort brought together the American Society of Breast Surgeons, Society of Breast Imaging, and College of American Pathology to develop management guidance for atypical lesions and LCIS. For FEA diagnosis, a 2026 review proposes a context-based approach that considers cytological and architectural features and helps distinguish FEA from overlapping findings, including apocrine proliferations and FEA within other breast lesions. The available summaries also identify persistent diagnostic uncertainty and limited prospective data as constraints on management.
Flat Epithelial Atypia (FEA): What It Means and How to Manage It
First defined in 2003, Flat Epithelial Atypia (FEA), previously termed columnar cell change/hyperplasia with atypia, involves epithelial changes in the terminal duct lobular units (TDLU). Histologically, FEA comprises one or more epithelial layers replacing normal epithelium within the TDLU acini, which are typically dilated and contain luminal calcifications. The lesional cells are monomorphic, featuring round, uniform nuclei lacking normal basal polarity. FEA cells resemble those in atypical ductal hyperplasia/low-grade ductal carcinoma in situ (DCIS), but without the epithelial architectural complexity; hence, the atypical epithelium is “flat.”
- Earlier Reports: Showed 10-30% of cases had invasive cancer or DCIS at surgical excision, supporting routine surgical excision.
- Recent Studies: Indicate lower upgrade rates, likely from improved lesion sampling using larger needles, vacuum-assisted techniques, and radiologic-pathologic concordance.
- Thorough Percutaneous Sampling: When all microcalcifications are removed, upgrade rates drop to 0-7%.
- Personal History Matters: Berry et al. found higher upgrade rates in women with a personal history of breast cancer (50%) versus those without (11%).
A Source Outside the Breast Lesion Evidence
The listed source is a surgical oncology manual excerpt about squamous cell carcinoma in situ of the anus (SISCCA), rather than atypical breast lesions. It says SISCCA is typically identified by high-resolution anoscopy (HRA). The excerpt notes that ongoing studies are investigating excision alone as treatment for SISCCA. It provides no research findings or recommendations about atypical breast lesions.
Screening and Diagnostic Complexity
Mammographic screening has increased detection of invasive breast cancers and of lesions regarded as precursors, such as ductal carcinoma in situ, as well as risk factors for later breast cancer, such as ADH. Atypical epithelial breast lesions form a heterogeneous group that includes ADH, ALH, FEA, atypia in a papilloma, atypical microglandular adenosis, and apocrine atypia; diagnosis can be challenging. FEA is described as a benign proliferative lesion with columnar cell changes and cytologic atypia, although it is often labeled atypical or high-risk. These source summaries establish diagnostic and classification challenges but do not provide comparative evidence that a particular management approach has failed.
FEA and Supplemental MRI
A 2026 summary of new guidelines says that FEA alone does not warrant supplemental MRI. It also says a second pathology review should be considered for FEA, particularly when the original interpretation comes from a non-specialized pathology practice. The reason given is that FEA may be reclassified as a higher-order lesion such as ADH. The supplied source does not provide a direct comparison of MRI outcomes or a broader comparison with other atypical lesions.
Making Informed Decisions
FEA, radial scars, and papillary lesions identified via percutaneous biopsy can be challenging to manage because of potential cancer underestimation. Radial scars and papillary lesions with atypia have a 25-30% risk of upgrade to cancer, warranting surgical excision. For FEA, radial scars, and papillary lesions without atypia, cancer upgrade risks are low if the lesion is well-sampled.
High-Risk Lesions and Long-Term Risk
A review of high-risk breast lesions covers atypical intraductal epithelial proliferation, lobular neoplasia—including LCIS and ALH—FEA, radial scar, and papillary lesions. A separate systematic review abstract states that biopsy-proven ADH, ALH, LCIS, and FEA are associated with increased subsequent breast cancer risk, while noting that long-term risk had not previously been synthesized. Together, these sources frame atypical lesions as a diverse group requiring attention to both diagnostic category and future risk. The supplied material does not provide specific long-term risk estimates.
Multisociety Guidance
In 2026, the American Society of Breast Surgeons, Society of Breast Imaging, and College of American Pathology released joint guidance addressing proliferative breast lesions with atypia and LCIS. The recommendations are described as evidence-informed and consensus-based, covering ADH, ALH, FEA, classic LCIS, pleomorphic LCIS, and florid LCIS. The guideline source says clinicians managing patients with atypical breast lesions or LCIS should consider integrating the recommendations into clinical management. The supplied summaries do not specify how adoption varies across practices.
FEA as a Proposed Precursor
FEA has been proposed as a precursor lesion on the pathway to breast cancer based on its cytologic features and its co-occurrence with atypical hyperplasia and breast cancer. It is also often referred to as an atypical or high-risk lesion. A review of atypical epithelial breast lesions emphasizes that this is a heterogeneous group and that diagnosis can be challenging. These sources describe the clinical framing of FEA but do not report patient experiences or individual outcomes.
Information should be considered when discussing with patients their preferences for surgical excision and longer-term surveillance. Long-term breast cancer risk for women with these lesions is modest (relative risk of 2) in the absence of atypical hyperplasia.
By understanding the nuances of these lesions, individuals can work closely with their healthcare providers to develop personalized management plans that balance the need for accurate diagnosis and risk reduction with the desire to minimize unnecessary interventions. This collaborative approach ensures the best possible outcomes for long-term breast health.