Mucinous cystic neoplasms of the pancreas: are we overestimating malignant potential?

Surgical resection is recommended for all mucinous cystic neoplasms (MCNs) of the pancreas as a result of: 1) lack of an accurate tumor marker for invasive cancer; 2) young age at diagnosis; and 3) historical studies revealing 36 per cent incidence of malignancy in resected lesions. This study compares the clinicopathologic and prognostic features of our series of resected MCNs to recent studies using the current International Association of Pancreatology (IAP) system. Thirty-eight resected MCNs were identified. Almost all patients were female (97.4%); median age at diagnosis was 53.5 years (interquartile range [IQR], 41.3 to 61.0). The majority occurred in the body/tail of the pancreas (86.8%); median size on computed tomography/magnetic resonance imaging was 5.0 cm (IQR, 3 to 8.8). Comparison of the five high-grade (HG, 13.2%) and 33 low-grade (86.8%) MCNs revealed that 1) patients were similar in age (55.0 vs 52.0 years, respectively) and 2) HG lesions were significantly larger on preoperative imaging (9.9 vs 3.5 cm) and final pathology (10.9 vs 3.5 cm). These data, taken together with five recent studies that adhere to the 2012 IAP criteria (385 total MCNs), reveal that a cutoff of less than 3 cm without mural nodules would have only missed one (0.26%) HG lesion. Surveillance of these lesions may be appropriate for some patients.