Prevalence of malignancy in patients with pure main duct intraductal papillary mucinous neoplasms.

Background: Risk of malignancy in main duct intraductal papillary mucinous neoplasm (MD-IPMN) ranges from 36% to 100% in the literature. Although surgical resection is recommended for all MD-IPMNs, the risk of malignancy based on main pancreatic duct (MPD) size alone remains unclear.

Objective: To assess the prevalence of malignancy in symptomatic and asymptomatic patients with pure MD-IPMN based on MPD size.

Design: Single-center retrospective study of prospectively collected data.

Settings: Tertiary referral center.

Patients And Interventions: Fifty-two patients with pure low-risk MD-IPMN. Clinical, endoscopic, radiographic, and pathologic data were reviewed.

Main Outcome Measurements: Prevalence of malignancy in patients with pure MD-IPMN based on histopathology of resected lesions.

Results: Sixteen asymptomatic patients had pure MD-IPMN on surgical pathology, 4 (25%) with malignant disease, compared with 25 of 36 symptomatic patients (69%) with pure MD-IPMN. Logistic regression identified symptoms and MPD size as predictors of malignancy. Receiver operating characteristic curve analysis demonstrated that MPD size (optimal cutoff of 8 mm) produced the greatest area under the curve to discriminate between benign and malignant MD-IPMN (.83; 95% CI, .72-.94). MPD size greater than 8 mm has a relative risk of 2.8 for malignancy (95% CI, 1.6-4.9).

Limitations: Retrospective, single-center study at a tertiary referral hospital. Study population included only patients who underwent surgical resection.

Conclusion: Asymptomatic MD-IPMN patients with a duct size of no more than 8 mm have a lower prevalence of malignancy and may represent a distinct group of patients with less aggressive biologic behavior. Further studies are needed to confirm our observations.