What are the relative disadvantages of FNA core needle biopsy and needle excision?
FNA: The results depend on the skill of the individual performing the procedure and the cytopathologist. There can be a high percentage of unsatisfactory aspirates (20% to 30% of cases). Invasive versus in situ cancer cannot be differentiated on FNA. The false-negative rate for image-guided FNA is unknown.
Core needle biopsy: Tissue displacement may occur during the biopsy procedure, resulting in misinterpretation of intraductal carcinoma as invasive carcinoma. Inversely, cancer can occasionally be understaged on core needle biopsy. That is, due to sampling, only DCIS may be biopsied and the invasive portion may not be sampled on a core biopsy.
Needle localization with excisional biopsy: This is the most expensive and most traumatic of all the biopsy procedures.