Malignant intraductal papillary mucinous neoplasm of the pancreas: in situ versus invasive carcinoma surgical resectability.
OBJECTIVE
To retrospectively evaluate computed tomographic (CT) findings in patients with in situ and invasive malignant intraductal papillary mucinous neoplasms (IPMNs) of the pancreas and to evaluate the accuracy for surgical resectability, with surgery and pathologic analysis as the reference standards.


METHODS
Institutional review board approval was obtained, and the informed consent requirement was waived. Forty-six patients with malignant IPMN proved at pathologic examination of the surgically resected specimen (n = 44) or laparotomy (n = 2) underwent surgery after multidetector CT was performed. CT findings were retrospectively evaluated to determine if a pancreatic malignant IPMN tumor was present; to make this determination, CT criteria were used to differentiate in situ from invasive tumors and signs of unresectability (liver metastasis, vascular CT pattern of encasement, or regional lymph node metastasis). The extent of the vascular CT pattern of encasement was recorded for each patient (no obliteration of the fat plane, obliteration of the fat plane of <50%, or obliteration of the fat plane of > or =50%). Statistical analysis was performed with the chi(2) and Student t tests.


RESULTS
CT revealed a mural nodule in the pancreatic duct wall in 14 patients with in situ carcinoma and one patient with invasive carcinoma (P < .003). CT revealed an infiltrative pancreatic mass in 17 patients with invasive carcinoma and two patients with in situ carcinoma (P < .02). Of the mural nodules, 93% were seen in patients with in situ carcinoma, whereas 90% of infiltrative pancreatic masses were observed in patients with invasive carcinomas. The positive predictive value of CT for determining resectability was 100%, and the overall accuracy of CT for determining resectability and unresectability was 74%. The positive predictive value of CT for determining unresectability was 17%, mainly owing to overestimation of arterial invasion.


CONCLUSIONS
CT is helpful in the differentiation of in situ and invasive IPMN. Classic vascular invasion criteria lead to the overestimation of surgical tumor unresectability in patients with malignant IPMN.
Vullierme
Marie-Pierre
MP
Department of Radiology, Beaujon Hospital, Clichy La Garenne, France. marie-pierre.vullierme@bjn.aphp.fr
Giraud-Cohen
Marie
M
Hammel
Pascal
P
Sauvanet
Alain
A
Couvelard
Anne
A
O'Toole
Dermot
D
Levy
Philippe
P
Ruszniewski
Philippe
P
Vilgrain
Valérie
V
D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000601:surgery*; D002288:Adenocarcinoma, Mucinous / Q000000981:diagnostic imaging / Q000601:surgery; D000231:Adenocarcinoma, Papillary / Q000000981:diagnostic imaging / Q000601:surgery; D000328:Adult; D000368:Aged; D021441:Carcinoma, Pancreatic Ductal / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D010180:Pancreatectomy / Q000379:methods*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome