No abstract

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound (EUS) guided fine-needle aspiration (FNA) biopsy, techniques of EUS-FNA, terminology and nomenclature of pancreatobiliary disease, ancillary testing and post-biopsy treatment and management. All documents are based on the expertise of the authors, a review of the literature, discussion of the draft document at several national and international meetings over an 18 month period and synthesis of online comments of the draft document on the Papanicolaou Society of Cytopathology web site [www.papsociety.org]. This document selectively presents the results of these discussions and focuses on a proposed standardized terminology scheme for pancreatobiliary specimens that correlate cytological diagnosis with biological behavior and increasingly conservative patient management of surveillance only. The proposed terminology scheme recommends a six-tiered system: Non-diagnostic, negative, atypical, neoplastic [benign or other], suspicious and positive. Unique to this scheme is the “neoplastic” category separated into “benign” (serous cystadenoma) or “other” (premalignant mucinous cysts, neuroendocrine tumors and solid-pseudopapillary neoplasms (SPNs)). The positive or malignant category is reserved for high-grade, aggressive malignancies including ductal adenocarcinoma, acinar cell carcinoma, poorly differentiated neuroendocrine carcinomas, pancreatoblastoma, lymphoma and metastases. Interpretation categories do not have to be used. Some pathology laboratory information systems require an interpretation category, which places the cytological diagnosis into a general category. This proposed scheme provides terminology that standardizes the category of the various diseases of the pancreas, some of which are difficult to diagnose specifically by cytology. In addition, this terminology scheme attempts to provide maximum flexibility for patient management, which has become increasingly conservative for some neoplasms.

Objective Invasive cancers arising from intraductal papillary mucinous neoplasm (IPMN) are recognised as a morphologically and biologically heterogeneous group of neoplasms. Less is known about the epithelial subtypes of the precursor IPMN from which these lesions arise. The authors investigate the clinicopathological characteristics and the impact on survival of both the invasive component and its background IPMN. Design and patients The study cohort comprised 61 patients with invasive IPMN (study group) and 570 patients with pancreatic ductal adenocarcinoma (PDAC, control group) resected at a single institution. Multivariate analyses were performed using a stage-matched Cox proportional hazard model. Results The histology of invasive components of the IPMN cohort was tubular in 38 (62%), colloid in 16 (26%), and oncocytic in seven (12%). Compared with PDAC, invasive IPMNs were associated with a lower incidence of adverse pathological features and improved mortality by multivariate analysis (HR 0.58; 95% CI 0.39 to 0.86). In subtype analysis, this favourable outcome remained only for colloid and oncocytic carcinomas, while tubular adenocarcinoma was associated with worse overall survival, not significantly different from that of PDAC (HR 0.85; 95% CI 0.53 to 1.36). Colloid and oncocytic carcinomas arose only from intestinal-and oncocytic-type IPMNs, respectively, and were mostly of the main-duct type, whereas tubular adenocarcinomas primarily originated in the gastric background, which was often associated with branch-duct IPMN. Overall survival of patients with invasive adenocarcinomas arising from gastric-type IPMN was significantly worse than that of patients with non-gastric-type IPMN (p=0.016). Conclusions Tubular, colloid and oncocytic invasive IPMNs have varying prognosis, and arise from different epithelial subtypes. Colloid and oncocytic types have markedly improved biology, whereas the tubular type has a course that resembles PDAC. Analysis of these subtypes indicates that the background epithelium plays an equally, if not more, important role in defining the biology and prognosis of invasive IPMNs.