Technical Differentiation And Clinical Application Boundaries Of Breast Biopsy Needle Types

https://www.mayoclinic.org/tests-procedures/breast-biopsy/about/pac-20384812

In the spectrum of breast biopsy needle types, hollow needle biopsy needles (CNB) and fine needle aspiration (FNA) needles are the two most representative branches, differing significantly in their technical principles and clinical value.

Hollow needle biopsy needles are "cutting" sampling tools; their core structure is a combination of a grooved core and an outer cannula. During the procedure, after the needle core is inserted into the lesion, the outer cannula is advanced to cut the tissue within the groove, obtaining a columnar tissue strip with a diameter of 1-2 mm and a length of 1-2 cm. Depending on the needle diameter, CNBs are further divided into automatic ejection type (e.g., 14G, 16G) and semi-automatic/manual type. The automatic ejection type relies on a spring mechanism to achieve integrated "insertion-cutting-needle withdrawal," requiring only a few seconds of operation time and achieving a sampling success rate of over 95%. It is currently the preferred method for image-guided breast biopsy (such as ultrasound and mammography). Its advantage lies in providing complete histological structures, allowing for the determination of tumor invasion depth, histological grade, and even immunohistochemical detection, providing crucial information for the formulation of neoadjuvant chemotherapy regimens for breast cancer.

Fine-needle aspiration needles are "aspiration" tools, typically using 21G-25G ultrafine needles connected to a 10ml negative pressure syringe. During the procedure, negative pressure suction draws cells from the lesion into the needle tube, creating a cell smear. The advantages of fine-needle aspiration (FNA) lie in its minimal invasiveness (only 0.5mm puncture site), lack of anesthesia, and low risk of complications, making it suitable for initial screening of multiple microcalcifications or cystic lesions. However, its limitations are also significant: it can only obtain cytological specimens, cannot observe tissue structure, and its diagnostic accuracy for benign lesions such as papilloma and sclerosing adenosis is only 60%-70%, and it is difficult to differentiate between carcinoma in situ and invasive carcinoma.

In clinical application, the two are not mutually exclusive: for palpable, obvious masses, FNA can be used as a primary screening method; if the results are questionable or the lesion is not palpable, further CNB (core needle biopsy) is required. The recent trend of "fine-needle hollowing" (such as 18G minimally invasive biopsy needles) is blurring the lines between the two-these needles combine the low invasiveness of fine needles with the histological sampling capabilities of hollow needles, providing a new option for the diagnosis of early, small lesions.