The natural history of the incidentally discovered small simple pancreatic cyst: long-term follow-up and clinical implications.

OBJECTIVE: The purpose of our study was to determine the natural history of small (</= 2 cm) simple pancreatic cystic lesions.
MATERIALS AND METHODS: A retrospective review was performed of patients with long-term follow-up who were diagnosed with small (</= 2 cm) simple pancreatic cysts on sonography or CT from 1985 to 1996. Long-term surveillance included radiographic surveillance of 5 years or longer, clinical follow-up of 8 years or longer, or response to questionnaire or telephone inquiry 8 year or longer after the original diagnosis. Cause of death was recorded for patients who died within 5-8 years of diagnosis. Patients were excluded if a history of pancreatitis or systemic cystic disease existed.
RESULTS: Seventy-nine patients had small simple pancreatic cysts. Forty-nine (62%) had adequate radiologic, clinical, or questionnaire follow-up. Of the 22 patients with radiologic follow-up, 13 (59%) had cysts that remained unchanged or became smaller (mean size, 8 mm; mean follow-up, 9 years), and nine (41%) had cysts that enlarged, from a mean of 14 mm to a mean of 26 mm (mean follow-up, 8 years). Of the 27 patients with clinical or questionnaire follow-up (mean follow-up, 10 years), none developed symptomatic pancreatic disease. Eighteen patients (23%) died within 8 years without adequate radiologic follow-up, none of pancreas-related causes. Twelve patients (15%) were lost to follow-up.
CONCLUSION: Although small, incidental, simple pancreatic cysts of 2 cm or smaller may enlarge over a prolonged time, morbidity or mortality due to these small simple cysts is extremely unlikely, and observation appears to be a safe management option.