Intraductal papillary mucinous tumors of the pancreas: imaging studies and treatment strategies

Abstract

Objective: We analyzed clinicopathologic and imaging features and the prognosis of intraductal papillary mucinous tumor (IPMT) of the pancreas to identify imaging findings indicative of malignancy and to establish the optimal treatment strategy.

Summary background data: In IPMT, preoperative differentiation between adenoma and adenocarcinoma is often difficult. Appropriate treatment based on pathologic study and surgical outcome has not been adequately documented.

Methods: Forty-one patients with IPMT underwent surgery; 15 with adenoma and 26 with adenocarcinoma; main duct type in 13, combined type in 12, and branch duct type in 16.

Results: In malignant IPMT, deep invasion was found in 62% and lymph node metastasis in 23% (peripancreatic nodes in 19% and distant nodes in 4%). Tumors with mural nodules (86%) had a significantly higher incidence of carcinoma than tumors without nodules (37%). IPMT with a main pancreatic duct > or =15 mm or tumor diameter > or =30 mm (branch duct type) showed a high prevalence of adenocarcinoma. Main duct (54%) and combined (58%) type tumor, and tumors with mural nodules (64%) often showed invasion. All five branch duct tumors less than 30 mm without nodules were adenomas. However, imaging studies could not definitely distinguish adenocarcinomas from adenomas. Complete resection was possible for all adenomas and 88% of adenocarcinomas. Five-year survival rates for patients with adenomas and adenocarcinomas were 100% and 82%, respectively.

Conclusions: IPMT has a favorable prognosis, regardless of deep invasion or node metastasis. IPMT requires peripancreatic node dissection in addition to complete tumor excision. Node dissection may be omitted for branch duct tumors less than 30 mm without mural nodules.