Cystic neoplasms of the pancreas and tumor-like lesions with cystic features: a review of 418 cases and a classification proposal

Abstract

Although cystic neoplasms and lesions of the pancreas are rare, they have attracted a great deal of attention because of their potential curability. Since, in recent years, several new entities have been identified, the relative frequency of the tumors and their classification need to be reevaluated. In a series of 1454 tumorous lesions of the pancreas collected between 1971 and 2003 in our surgical pathology files and consultation files, all cystic pancreatic neoplasms and tumor-like lesions were identified and typed both histologically and immunohistochemically. There were 418 cases (29%) showing cysts with a diameter ranging between 0.5 cm and 27 cm. Most common were solid pseudopapillary neoplasms (21%) and intraductal papillary-mucinous neoplasms (18%). When only the cystic neoplasms and lesions that had been resected in a single institution were considered, intraductal papillary mucinous neoplasms were the most frequent cystic neoplasms, while solid pseudopapillary neoplasms took fifth place behind ductal adenocarcinomas with cystic features, serous cystic neoplasms and mucinous cystic neoplasms. The most frequent cystic tumor-like lesions were pancreatitis-associated pseudocysts. New and rare entities that have recently been identified are mucinous nonneoplastic cysts, acinar cell cystadenomas and cystic hamartomas. Bearing in mind that figures from referral centers such as ours may be biased regarding the relative frequency of lesions, we concluded from our data that intraductal papillary-mucinous neoplasms are the most frequently occurring pancreatic cystic neoplasms, rather than solid pseudopapillary neoplasms. It was possible to classify all cystic lesions encountered in our files or described in the literature in a new system that distinguishes between neoplastic and nonneoplastic lesions, with further subdivisions into epithelial (adenomas, borderline neoplasms and carcinomas) and nonepithelial tumors. This classification is easy to handle and enables a distinction on the basis of clinical behavior and prognosis.

Pancreatic ductal adenocarcinomas with cystic features: neither rare nor uniform

“…In a recent study on cystic neoplasms and lesions of the pancreas we were able to show that pancreatic ductal adenocarcinomas with cystic features accounted for 7% of all cases. 3 Since similar figures have also been reported by other authors, 16,17,21 pancreatic ductal adenocarcinomas with cystic features are among those cystic neoplasms that have to be considered, when a tumorous cystic change of the pancreas is detected by imaging procedures.…”

“…3 Intraductal papillary-mucinous neoplasms, in contrast to 'large-gland type' pancreatic ductal adenocarcinomas, are localized in the main pancreatic duct and have an intraductal papillary mucin-producing tumor component, which is often MUC1 negative and MUC2 positive. 23,35 When invasive, the invasive component may assume the appearance of a usual ductal adenocarcinoma or a mucinous noncystic carcinoma.…”

“…The most common cystic tumors are intraductal papillary-mucinous neoplasms, serous cystic neoplasms, mucinous cystic neoplasms and solid pseudopapillary neoplasms. 2,3 Rare cystic neoplasms include acinar cell cystadenocarcinomas, 4 acinar cell cystadenomas, 5 cystic endocrine tumors 6 and cystic mesenchymal tumors. 7 The differential diagnosis of pancreatic cystic neoplasms, however, also includes pancreatic ductal adenocarcinomas with cystic changes.…”

Solid tumors of the pancreas can put on a mask through cystic change

“…German cases of cystic PDAC showed same staining patterns as the PDAC [8]. Central necrosis may result in a unilocular cyst surrounded by a rim of viable malignant tissue [9]. Pseudocysts in patients with no history of chronic pancreatitis should be closely evaluated for differential diagnosis of malignancy [3,10,11].…”

Light scattering spectroscopy identifies the malignant potential of pancreatic cysts during endoscopy

“…Therefore, the decision to consider surgery for a pancreatic cyst requires the treating physician to weigh data from potentially inaccurate EUS-FNA results with several even less conclusive imaging tests and with the patient’s ability to tolerate the surgery. As a result, of the pancreatoduodenectomies which are performed on cystic lesions, only about 42% are later confirmed as featuring precursor lesions with malignant potential 11 . On the other hand, precancerous and small resectable cancerous cysts, when left untreated, have the risk of progressing to incurable cancer.…”