9 - Breast

Abstract

Fine-needle aspiration (FNA) of breast remains an important tool for the diagnosis of breast lesions. Breast FNA is reported using diagnostic categories (the Yokohama System) that convey the degree of risk for malignancy and are aligned with therapeutic options. In addition to FNA, cytologic examination is often used in the setting of a nipple discharge. It is critical to differentiate breast cancer from benign conditions such as fibroadenoma, pregnancy/lactation change, fibrocystic changes, fat necrosis, and radiation effect. Careful attention to architectural features such as cellular configuration, cohesion, and nuclear atypia help avoid false-negative and false-positive diagnoses. Various types of breast neoplasia can be diagnosed by FNA, including papillary lesions, lobular carcinoma, medullary carcinoma, mucinous carcinoma, tubular carcinoma, and metaplastic carcinoma. With the increasing use of implants for breast reconstruction, the postimplantation seroma and associated anaplastic large-cell lymphoma are new diagnostic entities that need to be recognized.