Background: Intraductal papillary mucinous tumor (IPMT) is a type of pancreatic cystic neoplasm. IPMT consists of intraductal papillary mucinous adenoma (benign IPMT) and intraductal papillary mucinous carcinoma (malignant IPMT). Preoperative diagnosis of malignancy is difficult; the invasiveness and metastatic character are not well known. The purpose of the study was to evaluate the optimal diagnostic and therapeutic strategy of IPMT.
Methods: Medical charts of 38 patients with final diagnosis of IPMT in Kyoto University Hospital were retrospectively reviewed. Preoperative imaging, mode of operation, and clinical and histopathologic findings were analyzed.
Results: In 38 IPMTs, imaging of localization was correct in 82% by computed tomography, 90% by ultrasonography, 70% by endoscopic retrograde cholangiopancreatography, 100% by magnetic resonance cholangiopancreatography, and 100% by endoscopic ultrasonography. Evaluation of malignancy by endoscopic ultrasonography resulted in sensitivity and specificity of 81% and 78%, respectively. Pylorus-preserving pancreaticoduodenectomy was preferably performed in 20 of 38 patients with IPMT. Twenty-two patients had histologically malignant disease. Half of them had an invasive component in the adjacent stroma. One case of malignant IPMT showed lymph node metastasis, and the patient had no recurrence after pancreaticoduodenectomy with regional lymphadenectomy. No case was diagnosed as margin positive; however, 27% showed a dysplasia with atypia in the epithelial cells of the cut edge of the pancreas. One patient with negative atypia at the cut edge of the pancreas developed a recurrent tumor in the remnant pancreas.
Conclusions: The preoperative diagnosis of malignancy is difficult, and 50% of malignant IPMT showed an invasive component. Thus, radical resection of the pancreas with regional lymph node dissection should be the choice of treatment. Lymph node metastasis and intraductal distant invasion should be carefully managed in the surgical treatment of these lesions.