Correlation between CT patterns and pathological classification of intraductal papillary mucinous neoplasm.

OBJECTIVE

To examine CT patterns of intraductal papillary mucinous neoplasm (IPMN), analyze their correlation with pathologic classification, and discuss the value of CT in the diagnosis and differential diagnosis of IPMN.

METHODS

CT patterns of 39 IPMN patients, whose clinical data were complete and whose diagnosis was confirmed by surgery and pathology, were classified into three types: (1) simple main pancreatic duct (MPD) dilation type, (2) MPD dilation with pancreatic cystic lesion type, and (3) simple pancreatic cystic lesion type. Correlations between the three CT types and Takada pathologic classification (MPD type, furcation type and mixture type) were analyzed. The 39 IPMN cases were pathologically classified as the benign group and the malignant/borderline group. CT characteristics including the presence or absence of mural nodules, intrafocal partitions, focal size and the degree of MPD and common bile duct (CBD) dilation were analyzed statistically.

RESULTS

A correlation was found between the CT simple MPD dilation type and the pathological MPD type, between the MPD dilation with pancreatic cystic lesion type and the furcation and mixture types, and between the simple cystic lesion type and the furcation type (p<0.001). The benign rate was 92% in patients without intrafocal mural nodules, and 42% in patients with intrafocal mural nodules. The difference between the two groups was statistically significant (p=0.003). The presence or absence of intrafocal partitions was not correlated with benignancy or malignancy (p=0.793). The maximum diameter of malignant/borderline lesions was bigger than that of benign ones (p=0.016). There was no significant difference in MPD and CBD diameters between the benign and malignant/borderline groups. Regardless of pathological classification, the MPD diameter was larger than the CBD diameter in all cases (p=0.02).

CONCLUSION

The three CT types of IPMN well correlated with the pathologic classification, which is helpful for analyzing CT manifestations and improving the accuracy of diagnosis. MPD dilation is usually larger than CBD dilation in IPMN patients, which is also helpful in the diagnosis and differential diagnosis of IPMN in the context of other related findings.