Flat Epithelial Atypia (FEA) is a specific finding identified by pathologists during a breast biopsy, usually performed due to microcalcifications seen on a mammogram. FEA represents a cellular change in the breast’s ductal and lobular structures. The cells are considered atypical, meaning they are not normal but are also not cancerous. The central question is whether this low-risk finding requires surgical removal (excision) or if it can be safely managed with observation. The management decision depends on assessing the lesion’s nature and the possibility of a more significant, missed diagnosis.
What Flat Epithelial Atypia Is
Flat Epithelial Atypia is a descriptive term for a lesion occurring in the terminal duct lobular units (TDLUs) of the breast. Under the microscope, the cells lining these small ducts and lobules appear slightly abnormal or atypical. These cells are typically columnar and display low-grade cytologic atypia, meaning they have mildly enlarged or irregular nuclei but lack the significant disorganization seen in higher-risk lesions.
FEA is categorized as a low-risk proliferative breast lesion. It is a distinct entity from lesions such as Atypical Ductal Hyperplasia (ADH), which carries a higher long-term risk of developing breast cancer. Despite this distinction, FEA is often found in association with other high-risk lesions or even certain types of breast cancer, which complicates its management. The finding itself does not cause physical symptoms and is almost always a microscopic discovery made after a core needle biopsy (CNB).
Why Excision is Often Considered
Surgical excision is frequently considered after an FEA diagnosis due to the risk of an “upgrade.” An upgrade refers to the discovery of a more serious lesion that the initial core needle biopsy (CNB) missed. This upgrade may be to a higher-risk precursor lesion, such as Atypical Ductal Hyperplasia, or to malignancy, such as Ductal Carcinoma In Situ (DCIS) or invasive breast cancer. Since the CNB only samples a small portion of the abnormality, the most atypical area may not have been captured.
Studies have quantified the upgrade risk for pure FEA—cases where no other atypical lesions were found on the biopsy. A meta-analysis of over 2,400 cases indicated a pooled upgrade rate to any form of breast cancer of approximately 5%. The risk of upgrading to invasive carcinoma is typically lower, around 1%, while the risk of finding DCIS is near 2%.
Excision acts as a definitive diagnostic step to ensure that the entire area of concern and the surrounding tissue are thoroughly examined by a pathologist. This is an attempt to mitigate the risk of a “sampling error” from the original core needle biopsy, which may have only grazed the surface of a more extensive abnormality. If the subsequent surgical specimen confirms only FEA with no associated higher-risk findings, the patient is spared the uncertainty of a missed diagnosis.
Navigating the Decision to Excise
The decision to proceed with surgical excision is not universal and depends on several patient- and procedure-specific factors. A key determinant is radiologic-pathologic concordance, which asks whether the FEA finding adequately explains the abnormality seen on imaging. If the imaging appears more suspicious than the FEA diagnosis suggests, or if the biopsy target was not fully sampled, excision is strongly favored to resolve the discordance.
The extent of FEA in the core biopsy sample is another important pathological variable. Pathologists may categorize the finding as “focal” versus “prominent.” Prominent FEA, meaning a greater volume of atypical cells, is associated with a higher potential upgrade risk. Additionally, if FEA is found alongside Atypical Ductal Hyperplasia (ADH) in the same biopsy, the risk of upgrade to cancer increases significantly, often prompting excision.
The adequacy of the initial core needle biopsy procedure is also heavily weighted. If the biopsy was performed for microcalcifications and post-biopsy imaging shows that the majority (over 90%) of the targeted calcifications were removed, the upgrade rate drops substantially. In cases of near-complete removal of the radiographic target, observation is more frequently considered. Finally, the patient’s personal risk profile, such as a history of prior breast cancer, may tilt the balance toward surgical management.
Surveillance and Long-Term Management
Once a management decision is made, a clear plan for long-term follow-up is established, whether the patient undergoes excision or observation. If the patient proceeds with surgical excision and the final pathology report confirms no upgrade—meaning no DCIS or invasive cancer was found—the long-term management typically involves increased surveillance. This includes more frequent clinical breast exams and annual mammograms, often starting six months after the procedure.
For patients managed with observation, the surveillance plan is more intensive and immediate to ensure no missed diagnosis is present. This typically involves short-term follow-up imaging, such as a mammogram or ultrasound, performed six to twelve months after the initial biopsy. If the imaging remains stable and the abnormality does not change or grow, the patient transitions to the increased annual surveillance schedule. Any change in the imaging appearance during the observation period triggers a recommendation for surgical excision.