Mucinous cystic neoplasms of the pancreas: high-resolution cross-sectional imaging features with clinico-pathologic correlation.

Abstract

To describe the high-resolution cross-sectional (MDCT/MRI) features of mucinous cystic neoplasms (MCN) of the pancreas with clinico-pathologic correlation; to identify imaging predictors of high-grade dysplasia/carcinoma; and to estimate MCN growth rate. Thirty-two women (mean age: 46; range, 25-79years) with resected MCN who underwent preoperative MDCT (n=20) or MRI (n=12) examinations over a 14-year period were included. Two radiologists examined retrospectively in consensus the following MDCT/MRI features: MCN location, size/volume, presence of capsule and thickness of the capsule, and presence of mural nodules, enhancing septations, calcifications, chronic pancreatitis, and main pancreatic duct dilation. Imaging features were correlated with clinical symptoms, biochemistry results, and histopathologic features. A univariate model was analyzed for the prediction of high-grade dysplasia/carcinoma. Preoperative MCN growth rate was assessed using a subset of patients with more than one imaging study available (n=6). Twenty-five (78%) patients presented with symptoms and 8 (25%) patients had abnormal serum biochemical values. Mean MCN maximum dimensions were 48×45×45mm with a mean volume of 169mL. MCN were located in the tail (n=18), body (n=10), neck (n=2), and (head=2); 30 (93.5%) MCN were encapsulated, 3 (9%) had calcifications, 4 (12%) showed enhancing nodules, 9 (28%) had enhancing septations, and 5 (15%) had main pancreatic duct dilation. Associated chronic pancreatitis was observed in 4 (12%) patients. The only predictors for high-grade dysplasia/carcinoma were MCN size and volume. Using a cut-off size greater than 8.5cm, the specificity and sensitivity for high-grade dysplasia/carcinoma were 97 and 60%, respectively (p=0.003; OR 81, 95% CI 3.9-1655.8). Mean MCN growth rate was estimated at 4.2mm/year with a doubling time of 8.23years. MCN size (>8.5cm) and volume are the only features on MDCT/MR imaging that correlate with high-grade dysplasia/carcinoma. The average growth rate for MCNs is slow at approximately 4mm per year.