Mucinous cystic neoplasm of the pancreas is not an aggressive entity: lessons from 163 resected patients.

Mucinous cystic neoplasms (MCNs) of the pancreas have often been confused with intraductal papillary mucinous neoplasms. We evaluated the clinicopathologic characteristics, prevalence of cancer, and prognosis of a large series of well-characterized MCNs in 2 tertiary centers.Analysis of 163 patients with resected MCNs, defined by the presence of ovarian stroma and lack of communication with the main pancreatic duct.MCNs were seen mostly in women (95\%) and in the distal pancreas (97\%); 25\% were incidentally discovered. Symptomatic patients typically had mild abdominal pain, but 9\% presented with acute pancreatitis. One hundred eighteen patients (72\%) had adenoma, 17 (10.5\%) borderline tumors, 9 (5.5\%) in situ carcinoma, and 19 (12\%) invasive carcinoma. Patients with invasive carcinoma were significantly older than those with noninvasive neoplasms (55 vs. 44 years, P = 0.01). Findings associated with malignancy were presence of nodules (P = 0.0001) and diameter > or =60 mm (P = 0.0001). All neoplasms with cancer were either > or =40 mm in size or had nodules. There was no operative mortality and postoperative morbidity was 49\%. Median follow-up was 57 months (range, 4-233); only patients with invasive carcinoma had recurrence. The 5-year disease-specific survival for noninvasive MCNs was 100\%, and for those with invasive cancer, 57\%.This series, the largest with MCNs defined by ovarian stroma, shows a prevalence of cancer of only 17.5\%. Patients with invasive carcinoma are older, suggesting progression from adenoma to carcinoma. Although resection should be considered for all cases, in low-risk MCNs (< or =4 cm/no nodules), nonradical resections are appropriate.