Possible oncogenesis of mucinous cystic tumors of the pancreas lacking ovarian-like stroma

Abstract

Background/aims: Clinicopathological features and postoperative results from mucinous cystic tumors of the pancreas (MCTs) were reviewed. MCTs with ovarian-like stroma (MCTs-OLS+; n = 6) and those lacking ovarian-like stroma (MCTs-OLS-; n = 4) were compared to elucidate the oncogenesis of MCT without OLS.

Patients and methods: Ten patients with MCT were studied.

Results: The 6 MCTs-OLS+ cases occurred in females and were located in the body and tail of the pancreas. The mean tumor size was 6.5 cm (range 2-11 cm). The majority (5/6) of MCTs-OLS+ were multilocular and exhibited tiny loculi on the cyst wall and septum characteristic of MCTs-OLS+. Pathological classifications were adenoma in 4 patients and noninvasive adenocarcinoma in 2 patients. All 6 patients were alive without tumor recurrence 6-124 months after tumor resection. Of the 4 MCTs-OLS- cases, 2 were males and 2 females; MCTs- OLS- were located in the tail of the pancreas. The mean tumor size was 6.9 cm (range 4-8.4 cm). Invasive cancer in the pancreatic parenchyma or extrapancreatic tissue was recognized in all 4 patients, and the pathological classification of epithelia of the cyst wall were adenocarcinomas. These findings were also compatible with common invasive ductal carcinomas of the pancreas with secondary retention cyst on pseudocyst. All patients died of the disease (15, 27, 31 and 80 months after resection, respectively). Whether or not OLS is specific for MCTs of the pancreas should be clarified in future studies.

Conclusion: The results of our study led to three hypotheses regarding the oncogenesis of MCTs-OLS-: (1) MCTs in which OLS disappears during the development of invasive carcinoma; (2) advanced cancer derived from intraductal papillary mucinous tumor of the pancreas, and (3) invasive ductal carcinoma of the pancreas with secondary cyst.