Whipple made simple for surgical pathologists: orientation, dissection, and sampling of pancreaticoduodenectomy specimens for a more practical and accurate evaluation of pancreatic, distal common bile duct, and ampullary tumors.

Pancreaticoduodenectomy (PD) specimens present a challenge for surgical pathologists because of the relative rarity of these specimens, combined with the anatomic complexity. Here, we describe our experience on the orientation, dissection, and sampling of PD specimens for a more practical and accurate evaluation of pancreatic, distal common bile duct (CBD), and ampullary tumors. For orientation of PDs, identification of the "trapezoid," created by the vascular bed at the center, the pancreatic neck margin on the left, and the uncinate margin on the right, is of outmost importance in finding all the pertinent margins of the specimen including the CBD, which is located at the upper right edge of this trapezoid. After orientation, all the margins can be sampled. We submit the uncinate margin entirely as a perpendicular inked margin because this adipose tissue-rich area often reveals subtle satellite carcinomas that are grossly invisible, and, with this approach, the number of R1 resections has doubled in our experience. Then, to ensure proper identification of all lymph nodes (LNs), we utilize the orange-peeling approach, in which the soft tissue surrounding the pancreatic head is shaved off in 7 arbitrarily defined regions, which also serve as shaved samples of the so-called "peripancreatic soft tissue" that defines pT3 in the current American Joint Committee on Cancer TNM. With this approach, our LN count increased from 6 to 14 and LN positivity rate from 50% to 73%. In addition, in 90% of pancreatic ductal adenocarcinomas there are grossly undetected microfoci of carcinoma. For determination of the primary site and the extent of the tumor, we believe bisectioning of the pancreatic head, instead of axial (transverse) slicing, is the most revealing approach. In addition, documentation of the findings in the duodenal surface of the ampulla is crucial for ampullary carcinomas and their recent site-specific categorization into 4 categories. Therefore, we probe both the CBD and the pancreatic duct from distal to the ampulla and cut the pancreatic head to the ampulla at a plane that goes through both ducts. Then, we sample the bisected pancreatic head depending on the findings of the case. For example, for proper staging of ampullary carcinomas, it is imperative to take the sections perpendicular to the duodenal serosa at the "groove" area, as ampullary carcinomas often extend to this region. Amputative (axial) sectioning of the ampulla, although good for documentation of the peri-Oddi spread of the intra-ampullary tumors, unfortunately disallows documentation of mucosal spread of the papilla of Vater tumors (those arising from the edge of the ampulla, where the ducts transition to duodenal mucosa and extending) into the neighboring duodenum. Axial sectioning also often fails to document tumor spread to the "groove" area. In conclusion, knowledge of the gross characteristics of the anatomic hallmarks is essential for proper dissection of PD specimens. The approach described above allows practical and accurate documentation and staging of pancreas, distal CBD, and ampullary cancers.

Isolated solitary ducts (naked ducts) in adipose tissue: a specific but underappreciated finding of pancreatic adenocarcinoma and one of the potential reasons of understaging and high recurrence rate.

The distinction of ductal adenocarcinoma from chronic pancreatitis remains one of the most difficult challenges in surgical pathology. The glandular units of invasive carcinoma are often well formed with well-polarized cells, appearing deceptively benign. Conversely, the ducts of chronic pancreatitis may be atypical and pseudoinfiltrative as a result of acinar atrophy and fibrosis. We recently noted isolated solitary ductal units (ISDs) in adipose tissue to be a reliable indicator of adenocarcinoma. In this study, the frequency of ISDs was investigated in 105 pancreatic resections with ductal adenocarcinoma and 32 with chronic pancreatitis only. ISD was defined as a solitary gland lying individually in adipose tissue, either directly abutting adipocytes or separated from them by only a thin rim of fibromuscular tissue. ISD was detected in 50/105 (47.6%) of pancreatic resections for ductal adenocarcinoma, but not in any resections with chronic pancreatitis only (specificity 100%; sensitivity 47.6%). Most of the ISDs were very well differentiated and cytologically bland. A small subset of these units represented vascular invasion, in which the carcinoma cells epithelialized the vessel lining, transforming the vessel into a duct-like structure, virtually indistinguishable from normal ducts or PanINs. The vascular nature of these units was verified by Elastic-Van Gieson stain and muscular markers highlighting the elastic lamina and muscular wall, respectively. ISDs were often located in histologic sections taken for the evaluation of the retroperitoneal margin and pancreatic-free surfaces where adipose tissue is more abundant. In conclusion, ISD lying in adipose tissue unaccompanied by other elements, present in 47.6% of pancreatic resections when peripancreatic soft tissues away from the tumor are sampled, is a very specific finding for carcinoma that may be instrumental in the diagnosis and staging of carcinoma as well as margin evaluation.