Noninvasive intraductal papillary mucinous neoplasm with para-aortic lymph node metastasis: report of a case

Intraductal papillary mucinous neoplasms (IPMNs) with an invasive carcinoma component are categorized as minimally invasive or invasive. The prognosis after resection of minimally invasive IPMNs has been reported to be similar to that after resection of noninvasive IPMNs. We report a case of noninvasive branchduct IPMN with multiple lymph node metastases, including para-aortic node involvement, treated successfully by distal pancreatectomy with lymph node dissection. The patient, a 72-year-old man, had two multilocular cysts in the pancreatic body, 22 mm and 14 mm in diameter, respectively, communicating with the main pancreatic duct. The primary tumor and nodal metastases had similar patterns of mucin expression. The primary tumor contained a region of carcinoma in situ (CIS) without histological evidence of stromal invasion; thus, it was diagnosed as minimally invasive carcinoma. We report this case to emphasize two important points: first, even small branch-duct IPMNs without any indications for resection can have a component of CIS or more advanced disease; and second, even branch-duct IPMNs without any apparent invasive component can be aggressive and spread to the lymph nodes. Therefore, nodal status should be assessed carefully in every patient, even if the primary IPMN is not advanced.