Diagnostic Concordance and Preoperative Risk Factors for Malignancy in Pancreatic Mucinous Cystic Neoplasms.

Background/aims: As pancreatic mucinous cystic neoplasms (MCNs) are considered premalignant lesions, the current guidelines recommend their surgical resection. We aimed to investigate the concordance between preoperative and postoperative diagnoses and evaluate preoperative clinical parameters that could predict the malignant potential of MCNs.

Methods: Patients who underwent surgical resection at Samsung Medical Center for pancreatic cystic lesions and whose pathology was confirmed to be MCN, between July 2000 and December 2017, were retrospectively analyzed.

Results: Among a total of 132 patients 99 (75%) were diagnosed with MCN preoperatively. The most discordant preoperative diagnosis was an indeterminate pancreatic cyst. The proportion of male patients was higher (24.2% vs 7.1%, p=0.05) in the diagnosis-discordance group and the presence of worrisome features in radiologic imaging studies, such as wall thickening/enhancement (12.1% vs 37.4%, p=0.02) or solid component/mural nodule (3.0% vs 27.3%, p=0.02), was lower in the diagnosis-discordance group. The presence of symptoms (57.7% vs 34.9%, p=0.02), tumor size greater than 4 cm (80.8% vs 55.7%, p=0.04), and radiologic presence of a solid component/mural nodule (42.3% vs 16.0%, p=0.01) or duct dilatation (19.2% vs 6.6%, p=0.01) were significantly associated with malignant MCNs.

Conclusions: In our study, the overall diagnostic concordance rate was confirmed to be 75%, and our findings suggest that MCNs have a low malignancy potential when they are less than 4 cm in size, are asymptomatic and lack worrisome features on preoperative images.