Location Matters in IPMN: Clinicopathological Differences, Malignancy Risk and Oncological Outcomes for Lesions Located in Head Vs Body and Tail of the Pancreas.

BACKGROUND:The clinico-pathological characteristics and accuracy of the current International Association of Pancreatology guidelines for IPMN in relation to its location within the pancreas has not been investigated. METHODS:751 patients who underwent pancreatic resection for IPMN in two tertiary referral centers were retrospectively categorized into subgroups according to location within the pancreas. Likelihood of worrisome features, high-risk stigmata (HRS), clinico-pathological features and presence of malignancy were compared. RESULTS:480 (64%) patients had IPMN in the ventral pancreas (i.e. head, uncinate process and neck), and 271(36%) in the dorsal gland (i.e. body/tail). Malignancy was present in 54% (n = 259) of patients with ventral IPMN and in 39% (n = 107) of those with dorsal lesions (p < 0.0001). There was a significantly higher proportion of intestinal epithelium in ventral IPMNs when compared to those in the dorsal pancreas, both in the general cohort and in invasive cancer group (27% vs 15%, OR: 1.94 95%CI:1.16-3.24 p = 0.006 and 31% vs 22% OR 1.52 95%CI: 0.77-3, p = 0.24 respectively). Patients with ventral IPMN more frequently presented with HRS (49%vs 37%, p < 0.001), while dorsal IPMN often showed only worrisome features (54%vs 43%, p = 0.06). ROC curve analysis identified optimal cut-off values for main pancreatic duct diameter of 9 mm in ventral IPMNs and 5 mm in dorsal IPMNs for malignancy prediction. CONCLUSIONS:Ventral IPMNs are more commonly resected and show higher rates of intestinal epithelium and malignancy compared with dorsal lesions. A MPD size > 5 mm in IPMNs of the dorsal pancreas is associated with a substantial risk of malignancy.