Ultrasound guided fine-needle aspiration cytology of breast lesions.

Breast biopsy consists in the collection of cells or tissue fragments from a breast lesion and their analysis by a pathologist. There are several types of breast biopsy defined on the basis of the type of needle used: fine-needle aspiration and biopsy performed with a spring-based needle. This article focuses on fine-needle aspiration performed under sonographic guidance.It is used mainly to assess cysts that appear to contain vegetations or blood or that are associated with symptoms; lesions and solid nodules that are not unequivocally benign; and axillary lymph nodes that appear suspicious on physical examination and/or sonography.In addition to distinguishing between benign and malignant lesions, ultrasound guided fine-needle aspiration also plays an important role in tumor grading and in immunocytochemical identifying specific tumor markers. This article describes the technique used and the possible causes of false negative and false positive findings. Despite its limitations, fine-needle aspiration has become a fundamental tool for the identification and preoperative management of malignant breast lesions.