Intraductal papillary-mucinous tumors arising in Santorini's duct: clinicopathologic features and the treatment of choice.

Almost all reported cases of intraductal papillary-mucinous tumors of the pancreas (IPMTs) originate from Wirsung's duct (WD), the main pancreatic duct, or their branches. IPMTs arising from Santorini's duct (SD) and its branches have rarely been reported. This article presents the clinicopathologic features of IPMTs originating in SD and its branches. Of 36 IPMTs resected in our institution, 5 originated in the region of SD: 3 in SD and 2 from its branches. Both SD and WD were dilated in all cases on radiographic and ultrasonographic studies. The maximum diameter of SD, determined by computed tomography or ultrasonography, was larger than that of WD in all cases. Seven reports of IPMT arising from SD have been published. Four lesions originated from SD and the others from its branches. Overall, 9 of 12 lesions (75%) were considered malignant. In conclusion, the coexistence of an IPMT and a dilated SD suggests an origin in the SD. These tumors have a high malignant potential and should be excised.