The distance of tumor spread in the main pancreatic duct of an intraductal papillary-mucinous neoplasm: where to resect and how to predict it

Background

The surgical decision regarding where to resect the pancreas is an important judgement that is directly linked to the surgical procedure. An appropriate surgical margin to resect intraductal papillary-mucinous neoplasm (IPMN) of the pancreas based on the distance of tumor spread (DTS) in the main pancreatic duct has not been adequately documented. We analyzed the appropriate surgical margin based on the DTS in the main pancreatic duct of IPMN and the positive rate at the pancreatic cut end margin.

Methods

Forty patients with main duct- or mixed-type IPMN diagnosed histopathologically who underwent surgery at Tokai University Hospital between 1991 and 2008 were retrospectively analyzed. The resection line was determined to achieve a 2-cm surgical margin in patients with main duct- or mixed-type IPMN and as limited a resection as possible to remove the dilated branch duct in patients with branch duct-type IPMN according to macroscopic type. The dysplastic state of the epithelium was judged as positive for carcinoma in situ (high-grade dysplasia) or adenoma (very low to moderate dysplasia) and judged as negative for hyperplasia or normal.

Results

The mean DTS in the main pancreatic duct was 41.6 ± 30.0 mm, and that of the distance of tumor absence was 13.6 ± 12.4 mm. The positive rate at the pancreatic cut end margin in frozen sections was 29.7%. The final positive rate at the pancreatic cut end margin was 26.2%. There has been no evidence of local recurrence in the remnant pancreas. DTS in the main pancreatic duct of IPMN was correlated with the maximum diameter of the duct (R = 0.678).

Conclusion

Distance of tumor spread offered important insights about the appropriate site to resect the pancreas and the positive rate at the cut end margin in IPMN.