Cystic lesions of the pancreas

Intraductal papillary mucinous neoplasm of the biliary tract: a real disease?

BACKGROUND

Despite increasing numbers of reports, biliary tract intraductal papillary mucinous neoplasm (BT-IPMN) is not yet recognized as a unique neoplasm. The aim of the present study was to define the presence of BT-IPMN in a large series of resected biliary neoplasms.

METHODS

From May 1994 to December 2006, BT-IPMN cases were identified by reviewing pathology specimens of all resected cholangiocarcinomas and other biliary neoplasms when cystic, papillary or mucinous features were cited in pathology reports.

RESULTS

BT-IPMN was identified in 23 out of 253 (9%) specimens using the strict histopathological criteria of IPMN. The most common presenting symptom was abdominal discomfort which was present in 15 patients (65%). Only one of the original operative pathology reports used the term IPMN; 16 (70%) used the terms cystic, mucinous and/or papillary. BT-IPMN was isolated to non-hilar extra-hepatic ducts in 12 (52%), intra-hepatic ducts in 6 (26%) and hilar extra-hepatic ducts in 5 patients (22%). Carcinoma was found in association with BT-IPMN in 19 patients (83%); 5-year survival was 38% after resection.

CONCLUSION

BT-IPMN occurs throughout the intra- and extra-hepatic biliary system and can be identified readily as a unique neoplasm. Broader acceptance of BT-IPMN as a unique neoplasm may lead to a better understanding of the pathogenesis of biliary malignancies.

Defining new pancreatic tumour entities by molecular analysis

Recent advances in molecular biology, biochemistry and genetics have broadened our understanding of tumourigenesis and of the maintenance and spread of pancreatic cancer far beyond traditional microscopic histopathological analysis. While the main focus of pancreatic cancer research has been on pancreatic ductal adenocarcinoma, molecular research has also led to a better understanding of rare tumours of the pancreas, as well as to the definition of previously unknown tumour entities that can only be identified through the application of molecular tools. Furthermore, molecular analysis increasingly reveals the genetic and cell biological heterogeneity of established tumour entities, making subclassification of tumours possible. Genetic and molecular approaches may, therefore, not only lead to a better understanding of the pathogenesis of pancreatic tumours, but also culminate in more precise diagnosis as well as individually tailored treatment strategies for affected patients.

Is serous cystadenoma of the pancreas a model of clear-cell-associated angiogenesis and tumorigenesis?

BACKGROUND

Similar to the other von Hippel-Lindau (VHL)-related tumors such as renal cell carcinomas and capillary hemangioblastomas, serous cystadenomas (SCAs) of the pancreas are also characterized by clear cells. Over the years, we have also noticed that the tumor epithelium shows a prominent capillary network.

METHODS

Eighteen cases of SCA were reviewed histologically, and immunohistochemical analysis was performed for CD31 and vascular endothelial growth factor (VEGF) as well as the molecules implicated in clear-cell tumorigenesis: GLUT-1, hypoxia-inducible factor-1 (HIF-1alpha), and carbonic anhydrase IX (CA IX).

RESULTS

There was an extensively rich capillary network that appears almost intraepithelially in all cases of SCA, which was confirmed by CD31 stain that showed, on average, 26 capillaries per every 100 epithelial cells. VEGF expression was identified in 10/18 cases. Among the clear-cell tumorigenesis markers, CA IX was detected in all cases, GLUT-1 and HIF-1alpha in most cases.

CONCLUSION

As in other VHL-related clear-cell tumors, there is a prominent capillary network immediately adjacent to the epithelium of SCA, confirming that the clear-cell- angiogenesis association is also valid for this tumor type. Molecules implicated in clear-cell tumorigenesis are also consistently expressed in SCA. This may have biologic and therapeutic implications, especially considering the rapidly evolving drugs against these pathways. More importantly, SCA may also serve as a model of clear-cell-associated angiogenesis and tumorigenesis, and the information gained from this tumor type may also be applicable to other clear-cell tumors.

Pancreatic cysts: pathologic classification, differential diagnosis, and clinical implications

CONTEXT

Cystic lesions of the pancreas are being recognized with increasing frequency and have become a more common finding in clinical practice because of the widespread use of advanced imaging modalities and the sharp drop in the mortality rate of pancreatic surgery. Consequently, in the past 2 decades, the nature of many cystic tumors in this organ has been better characterized, and significant developments have taken place in the classification and in our understanding of pancreatic cystic lesions.

OBJECTIVE

To provide an overview of the current concepts in classification, differential diagnosis, and clinical/biologic behavior of pancreatic cystic tumors.

DATA SOURCES

The authors' personal experience, based on institutional and consultation materials, combined with an analysis of the literature.

CONCLUSIONS

In contrast to solid tumors, most of which are invasive ductal adenocarcinomas with dismal prognosis, cystic lesions of the pancreas are often either benign or low-grade indolent neoplasia. However, those that are mucinous, namely, intraductal papillary mucinous neoplasms and mucinous cystic neoplasms, constitute an important category because they have well-established malignant potential, representing an adenoma-carcinoma sequence. Those that are nonmucinous such as serous tumors, congenital cysts, lymphoepithelial cysts, and squamoid cyst of pancreatic ducts have no malignant potential. Only rare nonmucinous cystic tumors that occur as a result of degenerative/necrotic changes in otherwise solid neoplasia, such as cystic ductal adenocarcinomas, cystic pancreatic endocrine neoplasia, and solid-pseudopapillary neoplasm, are also malignant and have variable degrees of aggressiveness.

Management of mucin-producing cystic neoplasms of the pancreas

During the last decade small lesions of the pancreas have been increasingly recognized in clinical practice. Among these lesions, mucin-producing cystic neoplasms represent a recently described and unique entity among pancreatic tumors. In 1996, the World Health Organization distinguished two different types of mucinous cystic tumors: intraductal papillary mucinous neoplasms (IPMNs) of the pancreas, which are characterized by mucin production, cystic dilation of the pancreatic ducts, and intrapapillary growth, and mucinous cystic neoplasms (MCNs), which are defined by ovarian-like stroma and in most cases do not communicate with pancreatic ducts. Further, IPMNs can be subdivided into main-duct type, mixed-type, and branch-duct type tumors. Older data did not distinguish among different subsets of cystic neoplasms of the pancreas, and consequently many databases were inconsistent. Histopathologically, both IPMNs and MCNs demonstrate a wide spectrum of cellular atypia ranging from mild mucinous hyperplasia to invasive adenocarcinoma. Because mucinous cystic neoplasms of the pancreas show significant differences in clinical behavior from patient to patient, knowledge of the clinicopathologic characteristics and natural history of specific subtypes of IPMNs and MCNs has become crucial for physicians working in the field of gastroenterology. The present work offers an overview of current and generally accepted clinical guidelines for the diagnosis and treatment of IPMNs and MCNs.

Xanthogranulomatous inflammation of the peripancreatic region mimicking pancreatic cystic neoplasm

Xanthogranulomatous inflammation (XGI) is histopathologically characterized by a marked proliferative fibrosis, parenchymal destruction, and infiltration of foamy histiocytes intermixed with other inflammatory cells. Herein, we report a case of a 73-year-old man without symptoms who was initially diagnosed with a pancreatic cystic tumor but later with XGI in the peripancreatic region. Although XGI has been reported to occur in various organs or tissues, such as the gallbladder, kidney, bone, stomach, colon, appendix, lymph nodes, and soft tissues, XGI involving the pancreas or its surrounding tissues is extremely rare. When a pancreatic cystic lesion does not have typical clinicoradiological features of common pancreatic cystic neoplasms, this pathologic condition should be considered in the differential diagnosis.

Large mucinous cystic neoplasm of the pancreas associated with pregnancy

Mucinous cystic neoplasms (MCNs) of the pancreas occur mostly in females and are potentially sex hormone-sensitive. However, a MCN occurring during pregnancy is quite rare. A 30-year-old woman in the tenth week of pregnancy was referred to us because of a rapid increase in left hypochondrial distending pain. On ultrasound, the patient had a large intra-abdominal cystic lesion. She was thereafter diagnosed with missed abortion and a computed tomography scan showed that the lesion was a cystic tumor 18 cm in diameter originating from the pancreatic tail. The patient subsequently underwent tumor resection with distal pancreatectomy, sparing the spleen. Histopathological analysis of the specimen revealed a pancreatic MCN with moderate dysplasia. Immunohistochemically, the tumor was positive for both estrogen and progesterone receptors. To our knowledge, this is the first reported case of pancreatic MCN with moderate dysplasia in association with pregnancy. Our case strongly indicates that pancreatic MCN is female-hormone dependent.

Identification of malignancy factors by analyzing cystic tumors of the pancreas

AIM

The diversity in the aggressiveness of cystic tumors of the pancreas - ranging from the usually benign serous cystadenoma to lesions of variable degrees of malignancy - was utilized for the identification of molecular factors that are involved in the occurrence of malignancy.

METHODS

We analyzed the transcript profiles of different cystic tumor types. The results were confirmed at the protein level by immunohistochemistry. Also, functional studies with siRNA silencing were performed.

RESULTS

Expression variations at the RNA and protein level were identified that are closely correlated with the degree of malignancy. Besides, all tumors could be classified effectively by this means. Many of the identified factors had not previously been known to be associated with malignant cystic lesions. siRNA silencing of the gene with the most prominent variation - the anti-apoptotic factor FASTK (Fas-activated serine/threonine kinase) - revealed a regulative effect on several genes known to be relevant to the development of tumors.

CONCLUSION

By a molecular analysis of rare types of pancreatic cancer, which are less frequent in terms of disease, variations could be identified that could be critical for the regulation of malignancy and thus relevant to the treatment of also the majority of pancreatic tumors.

Progressive metaplastic and dysplastic changes in mouse pancreas induced by cyclooxygenase-2 overexpression

Cyclooxygenase-2 (COX-2) overexpression is an established factor linking chronic inflammation with metaplastic and neoplastic change in various tissues. We generated transgenic mice (BK5.COX-2) in which elevation of COX-2 and its effectors trigger a metaplasia-dysplasia sequence in exocrine pancreas. Histologic evaluation revealed a chronic pancreatitis-like state characterized by acinar-to-ductal metaplasia and a well-vascularized fibroinflammatory stroma that develops by 3 months. By 6 to 8 months, strongly dysplastic features suggestive of pancreatic ductal adenocarcinoma emerge in the metaplastic ducts. Increased proliferation, cellular atypia, and loss of normal cell/tissue organization are typical features in transgenic pancreata. Alterations in biomarkers associated with human inflammatory and neoplastic pancreatic disease were detected using immunohistochemistry. The abnormal pancreatic phenotype can be completely prevented by maintaining mice on a diet containing celecoxib, a well-characterized COX-2 inhibitor. Despite the high degree of atypia, only limited evidence of invasion to adjacent tissues was observed, with no evidence of distant metastases. However, cell lines derived from spontaneous lesions are aggressively tumorigenic when injected into syngeneic or nude mice. The progressive nature of the metaplastic/dysplastic changes observed in this model make it a valuable tool for examining the transition from chronic inflammation to neoplasia.

Cystic lesions of the pancreas. A diagnostic and management dilemma

BACKGROUND/AIMS

Due to enhanced imaging modalities, pancreatic cysts are being increasingly detected, often as an incidental finding. They comprise a wide range of differing underlying pathologies from completely benign through premalignant to frankly malignant. The exact diagnostic and management pathway of these cysts remains problematic and this review attempts to provide an overview of the pathology underlying pancreatic cystic lesions and suggests appropriate methods of management.

METHODS

A search was undertaken with a Pubmed database to identify all English articles using the keywords 'pancreatic cysts', 'serous cystadenoma', 'intraductal papillary mucinous tumour', 'pseudocysts', 'mucinous cystic neoplasm' and 'solid pseudopapillary tumour'.

RESULTS

The mainstay of assessment of pancreatic cysts is cross-sectional imaging incorporating CT and MRI. Fine-needle aspiration (FNA) (often with endoscopic ultrasound) may provide valuable additional information but can lack sensitivity. Symptomatic cysts, increasing age and multilocular cysts (with a solid component and thick walls) are predictors of malignancy. A raised cyst aspirate CEA, CA 19-9 and mucin content (including abnormal cytology), if present, can accurately distinguish premalignant and malignant cysts from benign ones.

CONCLUSION

In summary, all patients with pancreatic cystic lesions, whether asymptomatic or symptomatic, must be thoroughly investigated to ascertain the underlying nature of the cyst. Small asymptomatic cysts (<3 cm) with no suspicious features on imaging or FNA may be safely followed up. Follow-up should continue for at least 4 years, with a repeat FNA if needed. An algorithm for the management of pancreatic cystic tumours is also suggested. and IAP.

New treatment for cystic tumors of the pancreas: EUS-guided ethanol lavage with paclitaxel injection

BACKGROUND

Cystic tumors of the pancreas are frequently detected and encompass a wide pathologic spectrum, ranging from benign to malignant. A substantial proportion of cystic tumors cannot be histologically classified, even after extensive diagnostic evaluation, and, therefore, ultimately require surgical resection. Recently, complete resolution of cystic tumors by EUS-guided ethanol lavage was reported in a pilot study.

OBJECTIVES

The aim of this study was to evaluate the safety, feasibility, and response after EUS-guided ethanol lavage with paclitaxel injection (EUS-EP) for cystic tumors of the pancreas.

DESIGN

A prospective study.

SETTING

A tertiary care, academic medical center, from July 2005 to November 2006.

PATIENTS

Fourteen patients who underwent EUS-EP were observed for more than 6 months. They were analyzed in terms of procedure safety, feasibility, and response.

INTERVENTION

EUS-EP.

MAIN OUTCOME MEASUREMENTS

To compare changes of cyst volume before and after an EUS-EP.

RESULTS

An EUS-EP was successfully performed in all cases except one patient in whom the cyst fluid was so viscous that it could not be sufficiently aspirated. Acute pancreatitis occurred in one patient, and minor complications, including hyperamylasemia (n = 6) and vague abdominal pain (n = 1), were observed. Complete resolution of a cystic tumor was observed in 11 patients and partial resolution in two patients, and a cyst persisted in one patient.

LIMITATIONS

A small patient number, a short follow-up time, a single treatment arm.

CONCLUSIONS

EUS-EP appears to be a safe, feasible, and effective method for treating cystic tumors of the pancreas. Further studies that involve larger populations and longer follow-ups are warranted.

Cystic neoplasia of the pancreas: pathology and biology

In contrast with solid tumors, most of which are invasive ductal adenocarcinoma with dismal prognosis, cystic lesions of the pancreas are often either benign or low-grade indolent neoplasia. Those that are mucinous, namely, intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs), constitute the most important category, not only because they are the most common, but more importantly because they have well-established malignant potential, representing an adenomacarcinoma sequence. While many are innocuous adenomas--in particular, those that are small and less complex, and in the case of IPMN, those that are branch-duct type are more commonly benign, some harbor or progress into in situ or invasive carcinomas. For this reason, pancreatic cysts with mucinous differentiation ought to be evaluated carefully, preferably by experts familiar with subtle evidences of malignancy in these tumors. In the past few years, the definition of IPMNs and MCNs has become more refined. The presence of ovarian-type stroma has now almost become a requirement for the diagnosis of MCN, and when defined as such, MCN is seen almost exclusively in women of perimenopausal age group as thick-walled multilocular cystic mass in the tail of the pancreas in contrast with IPMN which afflicts an elder population, both genders in almost equal numbers, and occur predominantly in the head of the organ. While mucinous lesions have well-established pre-malignant properties, most of the entities that fall into the nonmucinous true cyst category such as serous tumors, lymphoepithelial cysts, congenital cysts, and squamoid cyst of ducts have virtually no malignant potential. In contrast, the rare cystic tumors that occur as a result of degenerative/necrotic changes in otherwise solid neoplasia such as the rare cystic ductal adenocarcinomas, cystic endocrine neoplasia, and most importantly, solid-pseudopapillary tumor (SPT) in which cystic change is so common that it used to be incorporated into its name ("solid-cystic," "papillary-cystic") are malignant neoplasia, albeit variable degrees of aggressiveness. SPT holds a distinctive place among pancreatic neoplasia because of its highly peculiar characteristics, undetermined cell lineage, occurrence almost exclusively in young females, association with beta-catenin pathway, and also by being a very low-grade curable malignancy. In conclusion, cystic lesions in the pancreas constitute a biologically and pathologically diverse category most (but not all) of which are either benign or treatable diseases; however, a substantial subset, especially mucinous ones, has malignant potential that requires careful analysis.

Cystic neoplasms of the exocrine pancreas

The increasing use of radiological imaging has led to greater detection of small and asymptomatic cystic lesions of the pancreas. Most are resectable, but not all are neoplastic. This review provides an update on the histopathology, immunohistochemistry, molecular biology, pathogenesis and management of cystic neoplasms of the exocrine pancreas. These include the serous, the mucinous cystic, the intraductal papillary mucinous and the solid pseudopapillary neoplasms. Recently reported variants are described and very rare cystic variants of other pancreatic epithelial and mesenchymal neoplasms are briefly mentioned.