The number of lymph nodes identified in a simple pancreatoduodenectomy specimen: comparison of conventional vs orange-peeling approach in pathologic assessment

Abstract

Lymph node status is one of the most important predictors of survival in resectable pancreatic ductal adenocarcinoma; therefore, thorough lymph node evaluation is a critical assessment in pancreatoduodenectomy specimens. There is considerable variability in pancreatoduodenectomy specimens processed histologically. This study compares two approaches of lymph node dissection and evaluation (standard vs orange peeling) of pancreatoduodenectomy specimens. A different approach to dissection of pancreatoduodenectomy specimens was designed to optimize lymph node harvesting: All peripancreatic soft tissues were removed in an orange-peeling manner before further dissection of the pancreatic head. This approach was applied to 52 consecutive pancreatoduodenectomy specimens performed for ductal adenocarcinoma at two institutions. Specimen dissection was otherwise performed routinely. Overall number of lymph nodes harvested, number of positive lymph nodes, and their anatomic distribution were analyzed and compared with cases that had been dissected by the conventional approach. The mean number of lymph nodes identified by the orange-peeling approach was 14.1 (by institution, 13.8 and 14.4), as opposed to 6.1 (by institution, 7 and 5.3) in cases processed by conventional approach (P=0.0001). The number of lymph node-positive cases also increased substantially from 50% (by institution, 54 and 46%) in the conventional method to 73% (by institution, 88 and 58%) in the orange-peeling method (P=0.02). The orange-peeling method of lymph node harvest in pancreatoduodenectomy specimens for ductal adenocarcinoma enhances overall and positive lymph node yield and optimizes ductal adenocarcinoma staging. Therefore, lymph node harvest by the orange-peeling method should be performed routinely before specimen sectioning in assessment of pancreatoduodenectomy for ductal adenocarcinoma.

Figure 1

Orange-peeling method. The peripancreatic soft tissues are dissected after margins were obtained but before sectioning of the pancreatic head. (a) Posterior surface of pancreatoduodenectomy specimen is seen before orange peeling. (b) The view after posterior pancreatoduodenal lymph node area (groove between pancreatic head and duodenal wall) is shaved off. (c) The view after posterior pancreatic surface is also orange peeled.

Figure 2

Pancreatic neck margin (green) and retroperitoneal margin (black) are seen before orange peeling (a, b). Retroperitoneal margin is inked black, cut as a 3-mm thick slice (c), bread-loafed, and entirely submitted on edge as perpendicular margin (d).