A novel approach to biliary tract pathology based on similarities to pancreatic counterparts: Is the biliary tract an incomplete pancreas?

There are peribiliary glands around the biliary tract, and these glands drain into the bile duct lumen. Interestingly, small amounts of pancreatic exocrine acini are intermingled with these glands. Experimental studies using animals suggest that the biliary tract shows some potential for pancreatic differentiation. It is noteworth that the biliary tract and pancreas have similar pathological features. IgG4‐related sclerosing cholangitis and autoimmune pancreatitis are representative inflammatory diseases with similar features. Intraductal papillary neoplasms are found in the biliary tract and also in the pancreas: intraductal papillary neoplasm of the bile duct (IPNB) and intraductal papillary mucinous neoplasm of the pancreas (IPMN). IPNB and IPMN share common histologic and phenotypic features and biological behaviors. Interestingly, mucinous cystic neoplasm (MCN) arises in both the pancreas and the heaptobiliary system. Intraductal tubular neoplasia is found in both the biliary tract and pancreas as well. Intraepithelial neoplasm is found in the biliary tract and pancreas: biliary intraepithelial neoplasm (BilIN) and pancreatic intraepithelial neoplasm (PanIN). BilIN and PanIN are followed by conventional invasive adenocarcinoma, while IPNB and IPMN are followed by tubular adenocarcinoma and mucinous carcinoma in both organs. Further study of the biliary tract's pathophysiology based on its similarity to pancreatic counterparts is warranted.     

胰腺导管内乳头状黏液性肿瘤的诊断和鉴别诊断

目的探讨胰腺导管内乳头状黏液性肿瘤的临床病理学特征及其与黏液囊性肿瘤的鉴别诊断要点。方法复习17例导管内乳头状黏液性肿瘤的临床病理学特征,与13例黏液囊性肿瘤对照;行HE染色及免疫组织化学EnVision法染色,检测肿瘤内黏液素MUC（1、2、5AC）的表达。结果17例导管内乳头状黏液性肿瘤中10例发生在男性;13例位于胰头。大体切面可观察到15例肿瘤与胰腺主导管相通。镜下可见到胰腺导管增生呈乳头状,并有上皮轻至重度不典型增生的改变。无卵巢样间质,肿瘤内交错出现萎缩或正常的胰腺腺泡和胰岛。9例主要表达MUC2,4例主要表达MUC5AC,4例伴有浸润癌者主要表达MUC1。13例黏液囊性肿瘤中11例发生于中老年女性;胰尾部10例,胰头1例,全胰腺2例;肿瘤与主导管不相通。组织学特征是含有卵巢样间质。肿瘤细胞主要表达MUC5AC,不表达MUC2,伴有浸润癌的2例,癌组织也表达MUC1。结论导管内乳头状黏液性肿瘤预后较好,患者性别、年龄、肿瘤部位、卵巢样间质、与主胰管是否相通及表达MUC2和（或）MUC1检测均可帮助诊断,并与黏液囊性肿瘤鉴别。后者主要表达MUC5AC。MUC1阳性提示侵袭性生物学行为。     

Endoscopic ultrasound-guided fine-needle aspiration cytology diagnosis of intraductal papillary mucinous neoplasm of the pancreas is highly predictive of pancreatic neoplasia

Intraductal papillary mucinous neoplasms (IPMN) have been considered difficult to diagnose by fine-needle aspiration (FNA) cytology. We identified 57 cases diagnosed as IPMN or consistent with IPMN by endoscopic ultrasound (EUS)-guided FNA over a 9-yr period. Histologic follow-up was available for 20 patients (35%). Pancreatic neoplasia was demonstrated in 18 of these cases (90%). The histologic diagnoses were IPMN (16 cases), pancreatic intraductal neoplasia (grade 1b, 1 case), invasive mucin-producing adenocarcinoma (1 case), and chronic pancreatitis with a pseudocyst (2 cases). Sixty-two cases of IPMN without coexisting adenocarcinoma were diagnosed by histology during this time period. Of these, 35 (56%) had a preceding EUS-guided FNA. The diagnosis made by EUS-guided FNA in these 35 cases was negative or nondiagnostic (6 cases), benign cyst (1 case), chronic pancreatitis (2 cases), atypical ductal cells (2 cases), adenocarcinoma or suspicious for adenocarcinoma (3 cases), consistent with mucinous cystic neoplasm (4 cases), and IPMN or consistent with IPMN (16 cases). An EUS FNA diagnosis of probable or definite neoplasia was, therefore, made in 71% of cases of histologically proven IPMN.     

Intraductal papillary mucinous neoplasm

Intraductal papillary mucinous neoplasm (IPMN) is a grossly visible (≥1 cm), mucin-producing neoplasm that arises in the main pancreatic duct and/or its branches. Patients with intraductal papillary mucinous neoplasm can present with symptoms caused by obstruction of the pancreatic duct system, or they can be asymptomatic. There are 3 clinical subtypes of intraductal papillary mucinous neoplasm: main duct, branch duct, and mixed. Five histologic types of intraductal papillary mucinous neoplasm are recognized: gastric foveolar type, intestinal type, pancreatobiliary type, intraductal oncocytic papillary neoplasm, and intraductal tubulopapillary neoplasm. Noninvasive intraductal papillary mucinous neoplasms are classified into 3 grades based on the degree of cytoarchitectural atypia: low-, intermediate-, and high-grade dysplasia. The most important prognosticator, however, is the presence or absence of an associated invasive carcinoma. Some main duct-intraductal papillary mucinous neoplasms progress into invasive carcinoma, mainly tubular adenocarcinoma (conventional pancreatic ductal adenocarcinoma) and colloid carcinoma. Branch duct-intraductal papillary mucinous neoplasms have a low risk for malignant transformation. Preoperative prediction of the malignant potential of an intraductal papillary mucinous neoplasm is of growing importance because pancreatic surgery has its complications, and many small intraductal papillary mucinous neoplasms, especially branch duct-intraductal papillary mucinous neoplasms, have an extremely low risk of progressing to an invasive cancer. Although most clinical decision making relies on imaging, a better understanding of the molecular genetics of intraductal papillary mucinous neoplasm could help identify molecular markers of high-risk lesions. When surgery is performed, intraoperative frozen section assessment of the pancreatic resection margin can guide the extent of resection. Intraductal papillary mucinous neoplasms are often multifocal, and surgically resected patients should be followed for metachronous disease.     

Cystic tumors of the liver: on the problems of diagnostic criteria

We report on three cases of cystic neoplasms of the liver with mucinous epithelium. Case 1 showed a low-grade cystic neoplasm with ovarian-like stroma (OS). Case 2 showed a low-grade cystic neoplasm without OS, and case 3 showed a high-grade cystic neoplasm without OS. In all three cases, bile duct communication (BDC) was absent. Currently, pancreatic mucinous cystic neoplasm (MCN) and intraductal papillary mucinous neoplasm of the pancreas (IPMN) are clearly distinguishable. However, MCN of the liver and intraductal papillary neoplasm of the bile duct (IPN-B) are not as easily distinguished. According to the latest WHO classification (2010), these conditions are classed as typical MCN of the liver, MCNs of the liver without OS, or IPN-Bs without BDC. The clinicopathological differences between MCN without OS and IPN-B without BDC are controversial. We present three cases describing these presentations and discuss the difficulties related to the diagnostic criteria used to distinguish between MCN of the liver and IPN-B.     

Biliary tumors with pancreatic counterparts

Some biliary diseases mimic pancreatic diseases pathologically as well as pathogenetically. Such diseases can be called “biliary diseases with pancreatic counterparts”. Biliary intraepithelial neoplasm (BilIN), intraductal papillary neoplasm of bile ducts (IPNB), hepatobiliary mucinous cystic neoplasm (hMCN), and IgG4-inflammatory pseudotumor represent the biliary counterparts of pancreatic intraepithelial neoplasm (PanIN), intraductal papillary mucinous neoplasm of pancreas (IPMN), pancreatic MCN, and mass forming type 1 autoimmune pancreatitis (AIP), respectively. BilIN and PanIN represent pre-invasive intraepithelial stages of nodular sclerosing cholangiocarcinoma and pancreatic ductal adenocarcinoma, respectively. IPNB and IPMN are grossly visible, predominant papillary, intraductal neoplasms that may progress to invasive carcinoma. Morphologically similar MCNs with subepithelial ovarian-like stroma occur in both the hepatobiliary system as well as the pancreas. IgG4-inflammatory pseudotumor, usually of the lymphoplasmacytic type, and mass forming type 1 AIP represent IgG4-related disease in the biliary tree and pancreas respectively. The biliary tract, which is associated with the peribiliary glands, including the pancreatic acini, can be regarded as an incomplete pancreas, so several diseases mimicking pancreatic diseases may be expected to occur in the biliary tract (biliary diseases with pancreatic counterparts).     

Cytologic features of pancreatic intraepithelial neoplasia and pancreatitis: Potential pitfalls in the diagnosis of pancreatic ductal carcinoma

Fine‐needle aspiration (FNA) has played a significant role in the diagnosis of pancreatic masses but false‐positive diagnoses occur. The Anatomic Pathology files were searched for FNAs of pancreas with subsequent resections. FNAs with a diagnosis of positive for or suspicious for adenocarcinoma followed by a benign resection specimen were reviewed and the surgical pathology and cytology findings correlated. Six cases had a cytologic diagnosis of adenocarcinoma or suspicious for adenocarcinoma but resection specimens were benign. In two cases, a non‐invasive intraductal papillary mucinous neoplasm (IPMN) without significant dysplasia was present surrounded by foci of pancreatic intraepithelial neoplasia (PanIN). In both cases, the degree of atypia within the IPMN was less than that seen cytologically. The nuclear features of the PanIN overlapped those seen in the smears. In two cases, a neuroendocrine neoplasm was present accompanied by multifocal PanIN. The cytologic features of the neuroendocrine neoplasm did not correlate with the material cytologically diagnosed as adenocarcinoma. The cytologically atypical epithelium was similar to the PanIN. Two diagnoses of adenocarcinoma were made cytologically but the pancreatectomy specimens revealed pancreatitis with reactive atypia. Cytologic diagnosis of pancreatic adenocarcinoma has high specificity. Six cytologic misdiagnoses of adenocarcinoma occurred in 105 patients. The cytologic features of these misdiagnoses correlated with histopathologic changes of intermediate to high‐grade PanIN or marked reactive atypia in severe pancreatitis. PanIN may be an under recognized, but significant source of false‐positive results. Diagn. Cytopathol. 2011. © 2010 Wiley‐Liss, Inc.     

Ruptured mucinous cystic neoplasm with an associated invasive carcinoma of pancreatic head in a pregnant woman: report of a case and review of literature

Mucinous cystic neoplasm (MCN) of the pancreas is characterized by mucin-producing columnar epithelium and an ovarian-type stroma. It occurs almost exclusively in women and is almost always located in the pancreatic body or tail. Here, we report a case of large MCN located in the pancreatic head but not in the body nor tail in a 32-year-old pregnant woman, which was thought to have grown rapidly during pregnancy. It was ruptured at 34 weeks of gestation and the patient was admitted to the emergency department of the University of Fukui Hospital with an acute abdomen. Emergency cesarean section followed by pancreaticoduodenectomy was performed. The tumor consisted of many small cysts lined by a single-layer of mucinous epithelium with papillary growth and partial solid parts showing invasive growth and sarcomatoid changes, indicating mucinous cystic neoplasm with an associated invasive carcinoma (previously referred as mucinous cystadenocarcinoma). Thickened septa revealed ovarian-type stroma strongly positive for α-inhibin and partly positive for progesterone receptor immunohistochemically. We also review and discuss previous reports of MCNs including those with an associated invasive carcinoma in pregnant patients.     

Invasive mucinous cystic neoplasms of the pancreas

Mucinous cystic neoplasms (MCN) and intraductal papillary mucinous neoplasms (IPMN) of the pancreas both appear to have been included and intermixed in some early reports of pancreatic cystic neoplasms. Recognition of their distinguishing features evolved during the last decade of the twentieth century. One legacy of the early period is the statement that mucinous cystic neoplasms sometimes progress to invasive colloid carcinoma. It is now recognized that colloid carcinomas characteristically arise from IPMN. We set out to see if we could find MCN that invaded as colloid carcinomas and found no examples in MCN collected in two academic medical centers. We then sought to expand the number of MCN by evaluating series from additional centers. This yielded no examples of colloid carcinomas associated with 291 MCN, however one MCN exhibited a minor component with colloid (non-cystic mucinous) growth pattern within the fibrous wall of the neoplasm. The expression of CDX2, a marker of intestinal differentiation that is found in colloid carcinomas was examined by immunostaining in the original MCN series and in the MCN with the intratumoral colloid growth pattern. Focal expression of CDX2 was found in 22 of 43 MCN including the MCN that exhibited the intratumoral colloid growth pattern. Overall, the data suggest that MCN rarely, if ever, invade as colloid carcinoma but the expression of CDX2 by some MCN and the observation of intratumoral colloid growth pattern in one MCN seems to leave open the possibility that MCN might rarely invade as colloid carcinoma.     

Histologic characteristics of pancreatic intraepithelial neoplasia associated with different pancreatic lesions

Pancreatic intraepithelial neoplasia (PanIN) has been found in association with pancreatic ductal adenocarcinoma, intraductal papillary-mucinous neoplasm (IPMN), mucinous cystic neoplasm, and other pancreatic lesions, but the characteristics of PanINs associated with these lesions are not well characterized. In this study, 185 partial or total pancreatectomy specimens were collected, and 173 had complete slides for reviewed, which included 74 pancreatic ductal adenocarcinomas, 28 IPMNs, 7 mucinous cystic neoplasms, 44 other nonductal tumors, and 20 nontumorous lesions. Differences in grade, extent, and duct involvement among PanINs associated with different lesions were analyzed. Patients with PanINs were older than those without, regardless of associated tumor or lesions. No sex predilection was noted. PanINs were found in 89%, 96%, 86%, 64%, and 55% pancreata with ductal adenocarcinomas, IPMNs, mucinous cystic neoplasm, other nonductal tumors, and nontumorous lesions, respectively. PanIN 1 and 2 were commonly associated with all types of lesions, but high-grade PanIN 3 was more frequently associated with ductal adenocarcinomas. Ductal involvement of PanINs was more extensive in association with ductal adenocarcinomas than in any other types of pancreatic tumors or lesions. PanINs associated with pancreatic ductal adenocarcinomas affected both the main and branched ducts, whereas PanINs associated with other types of pancreatic tumors or lesions were mainly present in the branch ducts. No statistical differences were observed in distribution, extent, and grade of PanINs among IPMNs, mucinous cystic neoplasms, other nonductal tumors, and nontumorous lesions. Our study demonstrated a high concurrence between PanINs and other precancerous lesions and histologic features of PanINs associated with different pancreatic diseases.     

Pseudointraductal papillary mucinous neoplasia caused by microscopic periductal endocrine tumors of the pancreas: a report of 3 cases

Intraductal papillary mucinous neoplasms constitute histologically distinctive pancreatic tumors characterized by cystically dilated pancreatic ducts lined by papillary epithelium, often with extensive mucin production. With increasing awareness of and vigilance for these tumors, there has been a surge in the incidence of intraductal papillary mucinous neoplasms in the last few decades. However, resections of presumed intraductal papillary mucinous neoplasms sometimes reveal other types of cystic lesions. Here we describe 3 cases of small, incidentally identified pancreatic endocrine tumors that focally compressed the main pancreatic duct and presented clinically, radiologically, and grossly as intraductal papillary mucinous neoplasm. The histology of the dilated ducts in all cases lacked convincing features of intraductal papillary mucinous neoplasm, prompting more careful examination of the specimens and eventual identification of small well-differentiated endocrine neoplasms. The constellation of findings represented by pancreatic endocrine neoplasm-associated duct stricture and dilatation can mimic intraductal papillary mucinous neoplasm clinically and pathologically. Awareness of this phenomenon can potentially avoid misdiagnosis of intraductal papillary mucinous neoplasm in such cases.     

Reappraisal of synchronous and multifocal mucinous lesions of the female genital tract: a close association with gastric metaplasia

Aims:  To describe the gastric phenotype of synchronous mucinous metaplasia and neoplasms of the female genital tract (SMMN–FGT).
Methods and results:  Six patients (mean age 57 years, range 39–83 years) were diagnosed with SMMN–FGT. All six patients had mucinous metaplasia of endometrium, which showed features of lobular endocervical glandular hyperplasia (LEGH)/pyloric gland metaplasia (PGM) in five and was associated with mucinous adenocarcinoma in three. Five patients had mucinous metaplasia of the fallopian tubes, of which three showed borderline features. Two patients had mucinous borderline tumour of the ovary. Five patients had cervical lesions including LEGH/PGM associated with either adenocarcinoma in situ or minimal deviation adenocarcinoma of the cervix. All mucinous lesions were positive for HIK1083 and/or MUC6. One patient with minimal deviation adenocarcinoma involving the vagina died of her disease, whereas five patients, including three with microinvasion and three with positive peritoneal cytology or mucinous ascites, were alive without recurrence after a mean follow-up of 46 months (range 13–102 months).
Conclusions:  There is a close association between SMMN–FGT and LEGH/PGM. Microinvasion and positive peritoneal cytology may not have an influence on outcome.     

Intraductal tubular adenoma (pyloric gland-type) of the pancreas: a reappraisal and possible relationship with gastric-type intraductal papillary mucinous neoplasm

Aims:  Intraductal tubular adenoma (ITA) is an uncommon intraluminal polypoid lesion that occurs in the main pancreatic duct and involves the main pancreatic duct in the region of head or body. Three cases of ITA are presented, the literature reviewed and their association with intraductal papillary mucinous neoplasm (IPMN) is postulated.
Methods and results:  ITA is composed of tightly packed tubular structures with focal cystic dilation and papillary areas lined by gastric/pyloric epithelium showing minimal to mild cytological atypia. Pancreatic intraepithelial neoplasia (PanIN) 1A and B was present in smaller ducts of all cases. In addition, in the cases in this report and 50% of cases reported in the literature, an associated gastric-type IPMN was present in the same duct as the ITA or in adjacent ducts. The coexistence of ITA and IPMN and the similarities of their epithelial lining (gastric/pyloric mucosa) suggest a possible pathogenic link.
Conclusions:  ITA can occur without (type A) or with (type B) an associated gastric-type IPMN. ITA could represent a localized, polypoid form of gastric-type IPMN.It is a benign lesion with no evidence of invasion and no direct tumour-related deaths. Its relationship to intraductal tubular carcinoma remains to be elucidated.     

Fine needle aspiration cytology of primary cutaneous mucinous carcinoma of axilla‐report of a rare case

Primary mucinous eccrine carcinoma is a rare malignant adnexal tumor of older patients. The histopathological features of this tumor are well‐established but the cytomorphology of this neoplasm has only been documented in a few cases. The cytology and histology of this tumor may mimic metastatic mucinous carcinoma and may cause a diagnostic dilemma, especially when the tumor is located at axilla. A correct diagnosis is important because the prognosis is better than that of a metastatic mucinous carcinoma. Here we report the cytological and histological features of a case of primary cutaneous mucinous carcinoma of axilla in an elderly male patient.     

Intraductal tubulopapillary neoplasm of the pancreas suspected by endoscopic ultrasonography–fine‐needle aspiration cytology: Report of a case confirmed by surgical specimen histology

Intraductal tubulopapillary neoplasm (ITPN) of the pancreas is rare compared with intraductal papillary mucinous neoplasm (IPMN). These entities are distinguished by endoscopic ultrasonography (EUS)–fine‐needle aspiration cytology (FNAC) on the basis of mucin production and the presence of a tubular or papillary growth pattern. In addition, there are several tumor types that should be distinguished from ITPN, such as solid pseudopapillary neoplasm, acinar cell carcinoma, and pancreatic neuroendocrine tumor. Herein, a case of an 80‐year‐old man with ITPN, which was suspected based on EUS‐FNAC findings at the time of review and confirmed by histological examination of the surgically resected specimen, has been presented. There have only been three reported cases that included the cytology of ITPN in the English language literature, all of which propose diagnostic features of ITPN based on cytological specimens. Here, a previously undescribed diagnostic feature of ITPN revealed by EUS–FNAC—tubules in contact with fibrovascular structures—correlated well with the histological findings of the surgically resected specimen, has been shown. Diagn. Cytopathol. 2015;43:1003–1006. © 2015 Wiley Periodicals, Inc.     

Intraductal papillary–mucinous neoplasm of the pancreas associated with polycystic liver and kidney disease

A case of intraductal papillary–mucinous neoplasm (IPMN) of the pancreas associated with polycystic liver and kidney disease is reported. A 63-year-old man was admitted to hospital with heartburn and upper abdominal pain. CT indicated multiple cysts in the liver and bilateral kidneys, and also showed multiple cystic lesions in the pancreatic head. Pancreatoduodenectomy was performed, and a pathological diagnosis of intraductal papillary–mucinous adenoma of branch duct type of the pancreas was made. He died of renal failure and hepatic failure due to recurrent cholangitis 12 years after the operation. An autopsy confirmed multiple cysts in the liver and kidneys. Multiple hepatic cysts were lined by biliary-type epithelium with no connection to the bile ducts. Peribiliary cysts were observed, and histology of the liver indicated von Meyenburg complexes. The kidneys showed that the cysts originated from all segments of the renal tubule. The autopsy findings suggested that the patient had suffered from autosomal-dominant polycystic kidney disease (ADPKD), but he did not have a family history of ADPKD. This case demonstrates that IPMN of the pancreas can occur as an extrarenal complication in patients with polycystic liver and kidney disease.     

The role of endoscopic ultrasound and endoscopic ultrasound-guided fine-needle aspiration in distinguishing pancreatic cystic lesions

Distinguishing mucinous from nonmucinous cystic lesions of the pancreas often constitutes a diagnostic dilemma. The clinical management differs between such lesions; therefore it is important to make an accurate preoperative diagnosis. Various centers have reported conflicting results regarding their ability to detect mucin-producing neoplastic cells and appropriately reach a diagnosis based on endoscopic ultrasound (EUS) guided FNA. The aim of this study is to assess the ability of EUS-FNA cytology to diagnose and differentiate mucinous from nonmucinous pancreatic cystic lesions. We reviewed records of patients who underwent EUS of pancreatic cystic lesions. If FNA was performed and mucinous neoplasm was suspected, aspirate was evaluated for cytomorphology and presence of mucin. FNA results were compared to final histologic diagnosis if surgery was performed.Cytologic diagnosis was provided for 28/30 (93%). By comparing EUS-FNA diagnoses with final surgical pathology, FNA accurately diagnosed in 10/11 cases with sensitivity and specificity for detection of malignancy of 100 and 89, respectively, while the accuracy for identification of mucinous cystic neoplasms was 100%. Our results indicate that in the appropriate clinical and imaging setting, EUS-FNA cytology with analysis for mucin production by tumor cells is an important test in distinguishing pancreatic cystic lesions and guiding further management.     

Expression and intracellular localization of matrix metalloproteinases in intraductal papillary mucinous neoplasms of the pancreas

To analyze the expression of matrix metalloproteinases (MMPs) and their relationships with the histological grades of the intraductal papillary mucinous neoplasm (IPMN) of the pancreas, we examined the frequency of expression and intracellular localization of MMP1, MMP2, MMP3, MMP7, and MMP9 in IPMN by immunohistochemistry. A total of 45 IPMN lesions (14 adenomas, 17 borderline lesions, nine noninvasive carcinomas, and five invasive lesions) from 21 patients were examined. MMP1, MMP2, MMP7, and MMP9 were expressed in tumor cells. Frequency of tumor cells expressing MMP7 was low in adenomas (median, 5.0%), higher in borderline lesions (median, 30.0%), in noninvasive carcinomas (median, 50.0%), and in invasive lesions (median, 80.0%), with a significant trend (P < 0.0001). Such a trend was also observed when the lesions were classified into gastric and intestinal subtypes (P < 0.0001 and P = 0.011, respectively). Basolateral expression of MMP7 in tumor cells was more prominent in lesions with higher histological grades (P < 0.0001). The frequency and the localization of MMP1, MMP2, and MMP9 did not correlate to the histological grades. MMP7 may contribute to the process by which IPMN advances from adenoma to carcinoma and to subsequent invasion of tumor cells in IPMN.     

Neoplastic intraepithelial lesions of pancreatic ducts: new entities

Intraductal neoplastic lesions of the pancreas have been the focus of recent efforts aiming to better characterize several entities. Beside reactive papillary hyperplastic lesion of pancreatic ducts whose limits and significance are unclear, two different entities, intraductal papillary mucinous neoplasm (IPMN) with its variant intraductal oncocytic papillary neoplasm, and pancreatic intraepithelial neoplasia (PanIN), the precursors of pancreatic adenocarcinoma have been recognized. Each has been carefully described at the microscopic level with classification into several grades of dysplasia. IPMNs are intraductal, papillary, often diffuse and mucus hypersecreting neoplastic lesions. Mucin accumulation gives to the lesion a cystic pattern. Treatment is surgical resection of the whole lesion. Intraductal oncocytic papillary neoplasm is a rare variant of IPMN. The prognosis of IPMN is globally favorable, but these tumors display the risk of malignant transformation into a mucinous or a tubular pancreatic adenocarcinoma. Although IPMN can induce symptoms, PanIN are silent and always discovered at the vicinity of an invasive adenocarcinoma. The usefulness and the reproducibility of the classification of PanIN remain to be determined. PanIN classification might resume the different successive steps of molecular genetic or epigenetic events associated with the development of a pancreatic carcinoma.