Endoscopic ultrasound-guided fine needle aspiration in cystic pancreatic lesions: is it still controversial?

We read with great interest the article by K. de Jong et al. entitled “Endoscopic ultrasound-guided fine-needle aspiration of pancreatic cystic lesions provides inadequate material for cytology and laboratory analysis: initial results from a prospective study” [1]. The authors performed endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) in 128 patients with pancreatic cystic lesions of varying sizes. The authors reported a very low technical success rate for FNA in their consecutive patients because adequate cellular material and sufficient fluid for biochemical analysis were obtained in only 44 out of 128 patients (34 %) and 68 out of 128 (53 %) respectively. They reported no significant difference between the sizes of the cysts in cases with or without a classifying diagnosis, or between cases from which sufficient fluid for biochemical analysis was or was not obtained. Nevertheless, they indicated that EUS-FNA was a safe technique that could be performed with a very low complication rate (2.4 %).

The authors recorded several morphologic characteristics of the cystic pancreatic lesions, such as a multiplicity of cysts, microcystic versus macrocystic character, septations, and nodules or calcifications; however, they did not give further data as to whether these findings had any relevance to the purpose of their study. Indeed, we believe that all these morphologic findings can potentially affect the cellularity and the volume of cyst fluid sampled. One of the main issues with this paper is that it reports that the size of the cystic lesion did not affect the adequacy of cellularity or sufficiency of fluid for biochemical analysis. We find this surprising because the type of cystic lesion or its micro/macrocystic nature is relevant to us when we are trying to ensure we obtain enough cystic material; the yield of fluid usually being small in a serous cystic lesion (due to its microcystic nature) so that a sampling error can easily occur. Furthermore, aspiration of mucinous lesions (although macrocystic in nature) may be difficult because of the fluid viscosity. The authors indicate that they used either 19-gauge or 22-gauge needles. Because the cellular atypia is always patchy in such lesions, which might hinder the adequacy of cellularity, 19-gauge needles would seem to be better from this point of view.

Another issue in this study is that it is not clear in the text whether the EUS experts performed cyst wall puncture and aspiration during the EUS-FNA procedure. It has been suggested that this technique increases the yield of FNA material for cytologic examination, especially for mucinous cysts [2]. We routinely do cyst wall puncture to improve the cellularity of samples during EUS-guided FNA of cystic pancreatic lesions. Another point is that it was unclear from this report whether there was an onsite cytopathologist or not. A cytopathologist present during the EUS examination can help us to confirm the adequacy of the cellularity of the sampled fluid or guide us to do a further puncture from another cyst in a multicystic lesion if the first puncture did not yield enough fluid with good cellularity. An onsite cytopathologist can also guide us to try other sampling methods, such as the cytobrush technique, at the same session if the cellularity of the aspirated cystic fluid is not good enough. In scant specimens we also know that EUS-guided FNA can provide us with cyst fluid for molecular analysis (K-ras mutation and allelic imbalances) that can help predict the malignant nature of a lesion.

Therefore, we believe that in our hands EUS and FNA are powerful tools, that EUS-guided FNA is a useful and safe procedure with low complication rates for assessing pancreatic cystic lesions, and that this is no longer a debatable or controversial issue in 2011. However, this should not prevent us from further improving our diagnostic techniques for the sake of our patients’ health.

References

• 1 de Jong K, Poley J W, van Hooft J E et al. Endoscopic ultrasound-guided fine-needle aspiration of pancreatic cystic lesions provides inadequate material for cytology and laboratory analysis: initial results from a prospective study.  Endoscopy. 2011;  43 585-590
• 2 Rogart J N, Loren D E, Singu B S et al. Cyst wall puncture and aspiration during EUS-guided fine needle aspiration may increase the diagnostic yield of mucinous cysts of the pancreas.  . 2011;  45 164-169