Modern therapies and iatrogenic changes in breast pathology.

Iatrogenic changes within the breast can provide challenges for the histopathologist in routine practice. Diagnostic procedures, such as core biopsies, result in reactive changes and can cause displacement of benign and malignant cells, the interpretation of which may cause difficulties in the resection specimen. Breast augmentation surgery with implants or injection of fillers, performed for cosmetic reasons or as part of a reconstructive process following removal of breast cancer, also produces reactive changes locally and at distant sites that may mimic cancer. The entity of implant-associated anaplastic large-cell lymphoma is now well recognized, with progress in our understanding of the underlying biological factors that drive its development. Chemotherapy and radiotherapy used in the treatment of breast cancer causes characteristic changes in normal breast tissue, and can alter the histological appearance and receptor status of the tumour. Radiotherapy to the breast, for breast cancer or childhood malignancies, increases the risk of developing a secondary malignancy in the breast long after treatment. In this review, we describe some of the iatrogenic changes that may be seen in histological specimens from the breast.