Endoscopic ultrasound-guided fine-needle aspiration and fine-needle biopsy for solid lesions: Does a “belt and suspenders” approach add value?Referring to van Riet PA et al. p. 37–44
18 December 2019 (online)
For over two decades, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has been the standard means of sampling both solid and cystic lesions of the luminal gastrointestinal tract, the pancreas, and surrounding structures. Rapid onsite evaluation (ROSE) of cytological samples has also been employed at the majority of centers performing EUS, and has been shown to increase tissue adequacy rates as well as provide clinicians and patients with a diagnosis in real time .
Recent years have seen the rise of EUS-guided fine-needle biopsy (FNB), also referred to as EUS-guided core biopsy. FNB samples are often true tissue cores that are, in general, larger and provide histological information . FNB samples can be used for a variety of special stains and molecular testing; this has become very important and, at many centers, standard practice in the era of personalized medicine.
“While FNA needles served us well for many years, I suspect their time in the limelight is waning.”
There remains ongoing debate about whether or not FNA or FNB is a superior technique for sampling solid lesions. Some feel that FNA is more than up to the task, especially given how well it has worked in clinical practice for so many years. FNA proponents also point to the lower cost of FNA needles compared with FNB needles. Advocates for FNB argue that histological samples allow a much more thorough pathological analysis to be undertaken, and that the cost difference between FNA and FNB needles, though real, is not large enough to prevent the adoption of FNB as a primary sampling technique.
A third group of endosonographers has investigated and sometimes advocated for the use of both FNA and FNB during the same procedure  . The idea behind this approach is that an FNA device can generate a sample to be analyzed via ROSE and thus obtain a diagnosis during the procedure, and an FNB device can be used to obtain core tissue samples for more detailed analysis at a later date.
In this issue of Endoscopy, van Riet et al. report on 73 patients who underwent EUS-FNA followed by EUS-FNB, or vice versa, for solid lesions . The diagnostic accuracy for malignancy with a single needle was 78 % (57/73), and this increased to 92 % (67/73) when both FNA and FNB needles were utilized (P = 0.002). The incremental yield of combined FNA and FNB over the use of one needle alone differed depending on which device was utilized first. FNA before FNB resulted in a significant increase in accuracy (P = 0.03), whereas the use of FNB first did not. A total of 16 patients were incorrectly diagnosed after a single needle was used, 10 of whom were able to achieve a diagnosis with a second device. Among these 10 patients, the second device was an FNB needle on 6 occasions, showing that both types of devices can (rarely) fail.
This is a curious study with an interesting hypothesis. This “belt and suspender” approach to sampling solid lesions during EUS procedures certainly has diagnostic merit, but I am left wondering about the downsides to dual sampling despite its obvious benefits. Clearly, using two needles (of any kind) will increase costs significantly, rendering moot any potential concerns about the increased cost of FNB needles compared with FNA needles. Furthermore, using two different needles will, by definition, increase procedure time, which has both safety and economic implications for the patient and the endoscopy laboratory, respectively.
The authors comment in their discussion that they feel that FNA needles are more flexible than FNB needles and thus can “reach and traverse difficult target lesions,” but this has certainly not been my personal experience in approximately two decades of performing EUS with all manner of FNA and FNB devices. The authors also correctly point out that FNB core samples can be used by cytopathologists to perform ROSE and this is the practice at my institution, weakening the argument for the use of FNA needles for this purpose  . To some extent, I wonder whether the “horse has left the barn” at this point, as FNB needles have now entered widespread use and the role of FNA appears to be declining. In my own practice, with rare exception, I only utilize FNA needles for sampling cystic lesions or during certain interventional EUS procedures. For patients with solid lesions, I virtually always perform FNB as my oncologists have come to expect core samples so that any additional testing they require can be obtained without repeat biopsy procedures.
Overall the authors of this study advocated using a FNB needle as a “logical first choice,” which I would agree with. While FNA needles served us well for many years, I suspect their time in the limelight is waning.
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