Reply to Lévy et al.

We appreciate the interest of Dr. Lévy and colleagues [1] in our report [2]. We agree that endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) should be performed to direct clinical management, meaning FNA results will affect surgical decision making. Our purpose in publishing this multicenter experience was twofold: (i) to increase awareness in the EUS community of this very rare entity, the solid pseudopapillary tumor (SPT), and (ii) to evaluate, we emphasize, the diagnostic accuracy of EUS-FNA in making a definitive diagnosis, as compared to surgical pathology. The key word here is ”diagnostic.” No patient in the series was referred with a pre-EUS suspicion of an SPT, and SPT was included in the differential diagnosis on the EUS report in only 50 % of cases in our series. Thus it was considered, but not necessarily suspected. This tumor is frequently misdiagnosed as a neuroendocrine tumor preoperatively. In the study by Bardeles et al., 50 % of the cases were diagnosed as neuroendocrine tumors based upon the EUS appearance [3]. In our series, five patients were diagnosed with neuroendocrine tumors by EUS-FNA cytology and immunostaining (as immunostains specific for SPT were not performed). Hence, our purpose herein of increasing awareness and recommending immunostain profiles when this lesion is considered, which will increase the diagnostic accuracy.

Regarding the influencing of surgical decision making, one could argue that a differential diagnosis of neuroendocrine tumor vs SPT is moot, as recommendations are to resect both. However, in the era of minimally invasive surgical approaches, a definitive preoperative diagnosis can influence decision making. Indeed, in our series, laparoscopic distal pancreatectomy was performed in 29 % based upon the definitive preoperative diagnosis. Our recent series reporting EUS-FNA results of nonfunctioning neuroendocrine tumors had a similar conclusion: definitive preoperative diagnosis led to a laparoscopic approach in 34 % of cases [4]. As physicians, don’t we owe it to our patients to recommend the least morbid treatment? And the other often forgotten factor is that patients, at least in our neck of the woods, want to know their diagnosis before undergoing a surgery that can carry a significant morbidity.

This brings us to the safety of the procedure. There were no complications related to the EUS-FNA procedure in our series, thus it is a safe procedure. Lévy et al. [1] infer that our procedures were not ”safe” given our short follow-up period. They insinuate that EUS-FNA will lead to peritoneal seeding, equating the FNA procedure (with a 22- or 25-g needle) to ”abdominal trauma” [5]. In the much more prevalent scenario of pancreatic cancer, tumor seeding has always been a concern. EUS-FNA has been found to be a much ”safer” approach compared with percutaneous biopsy, with a far smaller incidence of tumor seeding [6]. In the case of EUS-FNA of pancreatic head tumors (25 % of our SPT series), the needle path is within the resection field, so the argument does not hold. Additionally, we are aware of only one case of tumor seeding due to EUS-FNA in the setting of pancreatic cancer [7]. To quote Lévy, ”a metastatic diffusion has never been shown after EUS-FNA in the setting of SPPT,” and we do not believe this fear should influence our evaluation of patients.

Competing interests: None

References

• 1 Lévy P, Auber A, Ruszniewski P. Do not biopsy solid pseudopapillary tumor of the pancreas!.  Endoscopy. 2008;  40
• 2 Jani N, Dewitt J, Eloubeidi M. et al . Endoscopic ultrasound-guided fine-needle aspiration for diagnosis of solid pseudopapillary tumors of the pancreas: a multicenter experience.  Endoscopy. 2008;  40 200-203
• 3 Bardales R, Centeno B, Mallery S. et al . Endoscopic ultrasound-guided fine-needle aspiration cytology diagnosis of solid pseudopapillary tumor of the pancreas: a rare neoplasm of elusive origin but characteristic cytomorphologic features.  Am J Clin Pathol. 2004;  121 654-662
• 4 Jani N, Khalid A, Kaushik N. et al . EUS-guided FNA diagnosis of pancreatic endocrine tumors: new trends identified.  Gastrointest Endosc. 2008;  67 44-50
• 5 Lévy P, Bougaran J, Gayet B. Diffuse peritoneal carcinosis of pseudo-papillary and solid tumor of the pancreas. Role of abdominal injury.  Gastroenterol Clin Biol. 1997;  21 789-793
• 6 Micames C, Jowell P S, White R. et al . Lower frequency of peritoneal carcinomatosis in patients with pancreatic cancer diagnosed by EUS-guided FNA vs. percutaneous FNA.  Gastrointest Endosc. 2003;  58 690-695
• 7 Paquin S C, Gariépy G, Lepanto L. et al . A first report of tumor seeding because of EUS-guided FNA of a pancreatic adenocarcinoma.  Gastrointest Endosc. 2005;  61 610-611