Role of Fine-Needle Aspiration in the Surgical Management of Pancreatic Neuroendocrine Tumors: Utility and Limitations in Light of the New World Health Organization Classification

Abstract

Context.-Pancreatic neuroendocrine tumors (PancNETs) are rare and tend to get overshadowed by their more prevalent and aggressive ductal adenocarcinoma counterparts. The biological behavior of PancNETs is unpredictable, and thus management is controversial. However, the new World Health Organization classification has significantly contributed to the prognostic stratification of these patients. Concurrently, there have been advances in surgical techniques for benign or lowgrade pancreatic tumors. These procedures include minimally invasive and parenchyma-sparing operations such as laparoscopy and enucleation.Objective.-To report on the utility and limitations of fine-needle aspiration in the preoperative evaluation and management of PancNETs.Design.-This was a retrospective review of our institutional tumor database from 2002 to 2012. There were 25 cases of PancNETs that were localized and staged by medical imaging and diagnosed by fine-needle aspiration.Results.-Fourteen patients underwent laparotomy, with some requiring only limited surgery; 4 had laparoscopic resections; 4 were serially observed without surgical intervention; and another 3 were inoperable. After a mean follow-up of 37 months, more than half of the patients had no evidence of disease, including most of those who underwent minimally invasive surgery.Conclusions.-Fine-needle aspiration is a useful diagnostic adjunct to medical imaging in the preoperative evaluation and management of PancNETs. However, there are limitations with regard to grading PancNETs using this technique.(Arch Pathol Lab Med. 2014;138:896-902; doi: 10.5858/ arpa.2013-0300-OA) C ross-sectional imaging, endoscopic ultrasound (EUS), and fine-needle aspiration (FNA) are important in the preoperative evaluation of pancreatic masses.1-4 Although the majority of pancreatic tumors are ductal adenocarcinomas, other neoplasms such as neuroendocrine tumors, acinar cell carcinomas, solid pseudopapillary neoplasms, cystic neoplasms, and metastases also occur. 5,6 Pancreatic neuroendocrine tumors (PancNETs) are a particularly interesting group of neoplasms because they can present clinically with neuroendocrine manifestations or remain silent until their presence is heralded by mass effect. They can be single and sporadic or can be a component of several syndromes.2-4 The biological behavior of PancNETs is unpredictable, especially in the absence of locoregional spread or metastases. Thus, the management is controversial. However, there is now a growing consensus that the new World Health Organization (WHO) classification has significantly contributed to the prognostic stratification of these patients.7-9 Concurrently, there have been advances in surgical techniques for benign or low-grade pancreatic tumors. These procedures include minimally invasive and parenchyma-sparing operations such as laparoscopy and enucleation.10-13 Herein, we report on the utility and limitations of FNA in the preoperative evaluation and management of PancNETs in light of these developments. MATERIALS AND METHO...

Accuracy of Pancreatic Neuroendocrine Tumour Grading by Endoscopic Ultrasound-Guided Fine Needle Aspiration: Analysis of a Large Cohort and Perspectives for Improvement

“…G3 tumours tend also to be larger at diagnosis, which influences the overall area punctured by FNA, and furthermore, they dilute the hotspot areas. Over-grading has also been described in the literature [9,20] and can be explained by the fact that some pNETs are contaminated by proliferating inflammatory cells, mostly lymphocytes or endothelial cells, which can sometimes be confounding on FNA material.…”

“…Since 2014 and the publication of our first paper [17], a few groups have done comparative studies between the Ki67-LI obtained on FNA and the corresponding resection specimens [2,9,15,16,[20][21][22][23][24]. Our study represents the largest to date, not only in terms of comparison of grading, but also in terms of Ki67-LI absolute values, between cytology and corresponding resection specimens, studying the influence of tumour size, the number of counted cells on FNA and overall and progression-free survival.…”

Algorithmic approach to neuroendocrine tumors in targeted biopsies: Practical applications of immunohistochemical markers

“…The proliferation index in fine-needle aspiration cell blocks should be interpreted with caution. 43,44,[47][48][49][50][51][52] Because neuroendocrine neoplasms can be quite heterogeneous with respect to their proliferative activity, small biopsy specimens often fail to meet the minimum requirements for formal grading. 43,44,[47][48][49][50][51][52] The reported concordance between endoscopic ultrasound-guided fineneedle aspiration cytology versus surgical pathology in NET grading (using the Ki-67 index) varies from 50% to 89.5%.…”

“…43,44,[47][48][49][50][51][52] Because neuroendocrine neoplasms can be quite heterogeneous with respect to their proliferative activity, small biopsy specimens often fail to meet the minimum requirements for formal grading. 43,44,[47][48][49][50][51][52] The reported concordance between endoscopic ultrasound-guided fineneedle aspiration cytology versus surgical pathology in NET grading (using the Ki-67 index) varies from 50% to 89.5%. 43,44,[47][48][49][50][51][52] Determination of the Site of Origin Given the treatment implications, a diagnosis of welldifferentiated NET may require further immunohistochemical workup to establish the site of origin, particularly if this information is ambiguous to the treating clinician.…”

“…The real challenge arises when distinguishing between low‐grade versus intermediate‐grade NETs. The proliferation index in fine‐needle aspiration cell blocks should be interpreted with caution . Because neuroendocrine neoplasms can be quite heterogeneous with respect to their proliferative activity, small biopsy specimens often fail to meet the minimum requirements for formal grading .…”