Background/aims: Intraductal papillary mucinous neoplasms of the pancreas (IPMNs) are consisted of two types; branch-duct type and main-duct type. Branch-duct type is more common and follows a better course than main- duct type. However, the natural history of branch-duct type IPMN has not been exactly verified yet. The aim of this study was to investigate the natural course of branch-duct type IPMN.
Methods: The medical records of 45 patients with branch-duct type IPMN diagnosed by pancreatogram were reviewed retrospectively. The mean age was 62.9+/-8.3 years old and the mean follow-up duration was 27.4+/-18.9 months. Demographic, clinical and radiologic characteristics were evaluated. The histological findings of specimens resected during the follow-up period were also analyzed.
Results: Ten (22.2%) out of 45 patients showed enlargement of the cysts during follow-up. Initial size of the cyst in patients with cyst enlargement were smaller than in patients without it in univariate analysis (p<0.01). Cysts less than 1.0 cm were significantly associated with cyst enlargement with odds ratio of 4.48 in multivariate analysis. Ten patients underwent surgical resection and pathologic examination revealed one carcinoma in situ and one invasive adenocarcinoma. The presence of mural nodule was associated with malignant change of IPMNs (p=0.02). None of unresected cases showed metastasis or disease-related death.
Conclusions: Natural history of branch-duct type IPMNs is generally good. The occurrence of mural nodule is associated with the malignant change of the cyst but not the speed of size increment.