Small cystic lesions of the pancreas: clinical significance and findings at follow-up

Background: Our purpose was to correlate the imaging findings of small cystic pancreatic lesions to the incidence of growth on follow-up imaging and their pathologic diagnoses. Methods: CT images for 159 patients with cystic pancreatic lesions were retrospectively evaluated and lesions were assessed for size, number, connection to the main pancreatic duct (MPD), MPD dilatation, and any presence of loculation, wall irregularity, thick septations, or solid components. A total of 86 patients had follow-up imaging with time periods of less than 6 months (n = 21), 6-12 months (n = 22), 1-2 years (n = 14), and greater than 2 years (n = 29). Lesion histology was available in 20 patients. Results: Lesions with pathologic correlation proved to be: side branch intraductal papillary mucinous neoplasm or tumor (IPMT) (n = 5), combined type IPMT (n = 4), nonmucinous cyst (n = 4), chronic pancreatitis (n = 2), and reactive atypia with nonmucinous fluid (n = 1), combined type IMPT with foci of adenocarcinoma (n = 1), mucinous adenocarcinoma (n = 2), and nonmucinous adenocarcinoma (n = 1). Lesions with solid components were significantly more likely to grow and be malignant (P < 0.05). The presence of MPD dilatation was more common in patients with combined type IPMTs or malignancies. No other factors were predictive of malignancy. Conclusions: Solid components are predictive of malignancy, and MPD dilatation should prompt consideration of surgery. Other cystic lesions can be followed.