The complicated anatomy of the pancreas and its surroundings and the confusing terminology of various resection margins have often rendered the accurate pathological evaluation of the pancreaticoduodenectomy specimens tricky for the pathologists. Moreover, there have been discrepancies in the reported frequencies of R1 resections of pancreatic cancers in past literature mostly due to 1) divergent definitions of R1 resections (e.g. the 1mm-rule by the British Royal College of Pathologists (RCPath) versus the 0 mm-rule by the International Union Against Cancer; 2) lack of consensus on the definition of resection margins (e.g. uncinate process margin, SMA margin, retroperitoneal margin, radial margin, anterior/posterior margins and SMV/PV groove margins); and 3) absence of a standardized pathological examination protocol (e.g. College of American Pathologists (CAP) protocol, RCPath protocol, International Study Group of Pancreatic Surgery (ISGPS) consensus (2014)).
The traditional method for grossing pancreaticoduodenectomy specimens is the “bivalving” technique, where the specimen is sectioned along the axes of the common bile duct and the main pancreatic duct. This way, the relationship between the tumor and the ductal systems and the ampulla of Vater can be examined. However, this technique often results in the distortion of the specimen especially after formalin fixation, hindering the identification of important margins such as the SMA and SMV/PV groove margins, and the planes of section are often inconsistent due to the anatomic variability of the bile duct and pancreatic duct.
The axial sectioning technique has been implemented into the routine grossing protocols for pancreatic head/uncinate process cancers in SNUH and SNUBH since 2014. The pancreatic neck, anterior, posterior, SMV/PV groove, SMA, bile duct and intestinal (proximal/distal) margins are inked differently on the uncut fresh specimen. The specimens are fixed without further manipulation, and then sliced axially from top to bottom. So far, in our experience this method has enabled easier reconstruction of the three-dimensional anatomy and microscopic interpretation of the circumferential margins. It was easier to correlate the pathology with the clinico-radiological findings. However, the number of blocks/slides per case increased with this procedure.
In this session, the gross examination and pathological reporting procedures for pancreaticoduodenectomy specimens and the definitions of resection margins will be discussed.