Natural history of indeterminate pancreatic cysts

The optimal treatment for incidental asymptomatic pancreatic cysts is not known. The purpose of this study was to determine whether nonmucinous cysts by cyst-aspiration analysis can be observed safely.

A prospective protocol was initiated in September of 1999 for all suspected cystic neoplasms. Asymptomatic patients with negative cyst aspirates (no extracellular mucin, and concentration of carcinoembryonic antigen in the cyst fluid <200 ng/mL) were followed-up clinically and radiographically.

Through December 2004, 221 patients have been evaluated, and 80 (36%) initially were operated. There were 141 (64%) patients with indeterminate cysts, 98 have been followed-up for more than 12 months. Compared with resected patients, observed patients were older (62 vs 56 y, P < .006), and had smaller cysts (2.4 vs 4.0, P = .001). At a mean follow-up period of 24 months, 4 patients (4%) were resected. The indication, time to resection, and pathology were as follows: 2 patients for symptoms (abdominal pain and obstructive jaundice) at 24 and 72 months, respectively: mucinous and serous cystadenomas; 1 patient for an increase in size (6.6 to 7.8 cm) at 18 months: lymphoepithelial cyst; and 1 patient for abdominal pain and increase in size (2.0 to 3.7 cm) at 41 months: pseudocyst. The only patient resected for a mucinous neoplasm had a cyst fluid carcinoembryonic antigen level of 896 ng/mL. In the remaining observed patients, 20 (23%) showed a decrease in cyst size, and 16 (19%) showed an increase in size (mean diameter change, 21%).

Initial follow-up evaluation indicates that asymptomatic patients without evidence of a mucinous neoplasm by cyst aspiration can be followed clinically and with interval imaging.