Displaced Epithelium in Breast Pathology: A Review

Background: Although iatrogenic displacement of epithelial cells after breast instrumentation is a well-documented phenomenon, it is usually underdiagnosed. Misinterpretation of this issue results in overtreatment of patients in some instances. Additionally, the hazard of tumor seeding and dissemination after needling is a concern to both clinicians and patients. Both issues are addressed in this narrative review. Methods: We searched PubMed for abstracts of English-language publications using keywords “needle track/tract” and “displaced epithelium/epithelial displacement/iatrogenic displacement,” which resulted in 439 records restricted to human subjects. We read all the abstracts and selected 27 manuscripts with the most relevance. Results: There are some histopathologic features that can be useful in differentiating between epithelial displacement and real invasion/metastasis. The risk of seeding or metastasis after needling is shown to be trivial. Factors militating against the growth of dislodged cells are also discussed. Conclusion: Epithelial displacement is an important issue in breast pathology that should be considered in every patient with a history of breast instrumentation.