Intraductal Tubular Adenoma of the Pancreas, Pyloric Gland Type

Radiological and Pathological Assessment of the 2017 Revised International Association of Pancreatology Consensus Guidelines for Intraductal Papillary Mucinous Neoplasm, With an Emphasis on the Gastric Pyloric Gland Type

OBJECTIVES

This study aimed to assess the pitfalls of the current International Association of Pancreatology guidelines (IAPCG2017) for pancreatic intraductal papillary mucinous neoplasm (IPMN) and identify the criteria for future guidelines.

METHODS

Eighty surgically resected, consecutive IPMN cases were analyzed. Data including tumor site, IPMN duct type, and surgery type were collected. Based on radiological data, cases were retrospectively classified as high-risk stigmata (HRS) and non-HRS. Pathological grades and histological subtypes of IPMN cases were determined. Severe stromal sclerosis of the IPMN septa/marked parenchymal atrophy in the upstream pancreas was investigated pathologically. Positive/negative predictive values of the IAPCG2017 were calculated. Clinicopathological features of HRS-benign cases (pathologically benign IPMN cases meeting the HRS criteria) were extracted.

RESULTS

The positive/negative predictive values were 72.7%/64.0%, 70.0%/34.6%, and 54.0%/63.3% for IAPCG2017, HRS-main pancreatic duct, and HRS-nodule criteria, respectively. The 15 HRS-benign cases (18.8%) included 13 pancreatoduodenectomies and 10 cases of gastric pyloric (GP) gland subtype. Severe upstream atrophy was significantly related to IPMN malignancy, unlike the severe sclerosis of IPMN septa.

CONCLUSIONS

Benign IPMNs of GP subtype are sometimes categorized as HRS with the IAPCG2017. Collecting data on the natural course of GP-IPMN is necessary. To evaluate upstream atrophy may be of value to predict IPMN malignancy.

Aggressive venous invasion in the area of carcinoma correlates with liver metastasis as an index of metastasis for invasive ductal carcinoma of the pancreas

BACKGROUND

Invasive ductal carcinoma of the pancreas (IDCP) predominantly causes death through liver metastasis (LM) and peritoneal dissemination with local recurrence. However, whether its venous invasion is from the enlarged carcinoma accompanied by tumor growth, or from a distinct carcinoma group, for which venous invasion is facilitated by proximity to the origin, is unclear. We analyzed the correlation between LM and venous invasion in patients with small IDCP tumors.

METHODS

Of 388 patients who were diagnosed with IDCP, 20 (5.2%) had tumors with diameters <2 cm. The follow-up period of the 20 patients with smaller tumors was 1-24 years.

RESULTS

The small-tumor group (n = 20) included 11 men and 9 women, aged 51-80 years. Five died of liver metastasis (LM group, n = 5) and 15 patients (non-LM group, n = 15) were either alive without recurrence (n = 11) or died of peritonitis carcinomatosa following local recurrence, subarachnoid hemorrhage, primary lung cancer, or old age (n = 1 for each cause of death). The LM and non-LM groups did not significantly differ in numbers of venous invasion by the carcinoma in IDCP and non-IDCP area of the pancreas. However, median numbers of invaded veins in the area of IDCP and percentage of invaded vein/total number of vein in IDCP area were significantly higher in the LM group.

CONCLUSION

Among patients with small IDCP tumors, the LM group showed more aggressive venous invasion by IDPC. Patients in whom ≥60% of veins were invaded by IDCP should be prepared for LM.

Intraductal papillary mucinous neoplasms of the pancreas: reporting clinically relevant features

Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas can exhibit a wide spectrum of macroscopic and microscopic appearances. This not only causes occasional difficulties for the reporting pathologist in distinguishing these tumours from other lesions, but is also relevant clinically. As evidence accumulates, it becomes clear that multiple macroscopic and histological features of these neoplasms are relevant to the risk for malignant transformation and, consequently, of prime importance for clinical patient management. The need for detailed reporting is therefore increasing. This review discusses the panoply of gross and microscopic features of IPMN as well as the recommendations from recent consensus meetings regarding the pathology reporting on this tumour entity.

Pathology of Pancreatic Cancer Precursor Lesions

To better understand pancreatic ductal adenocarcinoma (PDAC) and improve its prognosis, it is essential to understand its origins. This article describes the pathology of the 3 well-established pancreatic cancer precursor lesions: pancreatic intraepithelial neoplasia, intraductal papillary mucinous neoplasm, and mucinous cystic neoplasm. Each of these precursor lesions has unique clinical findings, gross and microscopic features, and molecular aberrations. This article focuses on histopathologic diagnostic criteria and reporting guidelines. The genetics of these lesions are briefly discussed. Early detection and adequate treatment of pancreatic cancer precursor lesions has the potential to prevent pancreatic cancer and improve the prognosis of PDAC.

Tumoral Versus Flat Intraepithelial Neoplasia of Pancreatobiliary Tract, Gallbladder, and Ampulla of Vater

Context.—The identification of a precursor lesion is important to understanding the histopathologic and genetic alterations in carcinogenesis. There are a plethora of terminologies that describe precursor lesions of the pancreatobiliary tract, ampulla of Vater, and gallbladder. The current terminologies for precursor lesions may make it difficult to understand the tumor biology. Here, we propose the concept of tumoral and flat intraepithelial neoplasia to improve our understanding of precursor lesions of many epithelial organs, including the pancreatobiliary tract, ampulla of Vater, and gallbladder.

Objective.—To understand the dichotomous pattern of tumoral and flat intraepithelial neoplasia in carcinogenesis of pancreatobiliary tract, ampulla of Vater, and gallbladder.

Data Sources.—Review of relevant literatures indexed in PubMed.

Conclusions.—Tumoral intraepithelial neoplasia presents as an intraluminal or intraductal, mass-forming, polypoid lesion or a macroscopic, visible, cystic lesion without intracystic papillae. Microscopically, tumoral intraepithelial neoplasia shows various proportions of papillary and tubular architecture, often with a mixed pattern, such as papillary, tubular, and papillary-tubular. The malignant potential depends on the degree of dysplasia and the cell phenotype of the epithelium. Flat intraepithelial neoplasia presents as a flat or superficial, spreading, mucosal lesion that is frequently accompanied by an invasive carcinoma. Tumoral and flat intraepithelial neoplasias are not homogeneous entities and may exhibit histopathologic spectrum changes and different genetic profiles. Although intraepithelial neoplasia showed a dichotomous pattern in the tumoral versus flat types, they can coexist. Tumoral and flat intraepithelial neoplasia can be interpreted as part of a spectrum of changes in the carcinogenesis pathway of each organ.

Intraductal tubular adenomas (pyloric gland-type) of the pancreas: clinicopathologic features are similar to gastric-type intraductal papillary mucinous neoplasms and different from intraductal tubulopapillary neoplasms

Background

Intraductal tubular adenoma of the pancreas, pyloric gland type (ITA), is an infrequent intraductal benign lesion located in the main duct and large branch duct of the pancreas. The purpose of this report is to introduce seven new cases and to compare their clinicopathologic features and KRAS mutations to gastric-type intraductal papillary mucinous neoplasms (IPMNs) and intraductal tubulopapillary neoplasms (ITPNs).

Methods

Clinical findings, morphologic features, immunophenotypes and KRAS alterations were investigated in 7 patients with intraductal tubular adenomas, 16 patients with gastric-type intraductal papillary mucinous neoplasms and 6 patients with intraductal tubulopapillary neoplasms.

Results

There were more female patients in the ITA and gastric-type IPMN groups, whereas the opposite pattern was observed in the ITPN group. ITAs and gastric-type IPMNs were lined by columnar cells, similar to pyloric glands, with large extracellular deposits of mucin. ITPNs were polypoid and papillary mass located in the pancreatic ducts, which did not show large deposits of mucin. All ITAs and gastric-type IPMNs expressed MUC5AC strongly and diffusely, and 3/6 ITPNs expressed MUC5AC focally and weakly. KRAS mutations were identified in 4 ITAs (4/7, 57%), 9 IPMNs (9/16, 56%) and 2 ITPNs (2/6, 33%).

Conclusion

The intraductal tubular adenoma should not be considered a precursor lesion of intraductal tubulopapillary neoplasms. No adequate data established ITA should separate as a specific entity from IPMNs.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_172

The discrete nature and distinguishing molecular features of pancreatic intraductal tubulopapillary neoplasms and intraductal papillary mucinous neoplasms of the gastric type, pyloric gland variant

Intraductal tubulopapillary neoplasms (ITPNs) are composed of tubulopapillary glands with high-grade dysplasia in the pancreatic duct. Intraductal papillary mucinous neoplasms of the gastric type, pyloric gland variant (IPMN-PGs) are composed of tubular glands mimicking pyloric glands with low-grade dysplasia and were formerly called intraductal tubular adenomas. Because of their apparent common tubular morphology, IPMN-PGs and ITPNs could be associated. While the former might progress to the latter, this has not been fully assessed. In this study, we compared the molecular features of ITPNs and IPMN-PGs to determine their association using formalin-fixed, paraffin-embedded tissues of 14 ITPNs and 15 IPMN-PGs. Somatic mutations in PIK3CA, GNAS, KRAS, and BRAF were determined by Sanger sequencing. Expression of phosphorylated AKT was examined by immunohistochemistry. Somatic PIK3CA mutations were found in 3 of 14 ITPNs (21.4%) but in none of the IPMN-PGs (p = 0.0996). In contrast, GNAS mutations were found in none of the ITPNs but in 9 of 15 IPMN-PGs (60.0%; p < 0.001). KRAS mutations were detected in 1 of 14 ITPNs (7.1%) and 12 of 15 IPMN-PGs (80.0%; p < 0.001). BRAF mutation was found in one ITPN but in none of the IPMN-PGs. Phosphorylated AKT expression in ITPNs was significantly more evident than that in IPMN-PGs (p = 0.0401). These results indicate that ITPNs and IPMN-PGs are molecularly distinct, suggesting that IPMN-PG does not progress to ITPN. Furthermore, the molecular features of IPMN-PGs are confirmed to be identical to those of IPMNs reported elsewhere. These results validate the current World Health Organization system that classifies pancreatic intraductal neoplasms into IPMN and ITPN and confirm that IPMN-PG is not a benign counterpart of ITPN. The term 'intraductal tubular adenoma' should be eliminated and replaced with IPMN-PG.

Classification, morphology and molecular pathology of premalignant lesions of the pancreas

Over the past few years there have been substantial advances in our knowledge of premalignant lesions of the pancreas. Given the dismal prognosis of untreated pancreatic cancer, and the small proportion of patients who are operative candidates, an understanding of these premalignant lesions is essential for the development of strategies for early diagnosis and prevention. The 2010 WHO classification has added new entities, including intraductal tubular papillary neoplasms (ITPNs), and clarified the nomenclature and grading of previously recognised precursor lesions of pancreatic adenocarcinoma, such as intraductal papillary mucinous neoplasms (IPMNs), mucinous cystic neoplasms (MCNs) and pancreatic intraepithelial neoplasia (PanIN). In particular, there has been an upsurge of interest in the natural history of IPMN, driven partly by improvements in imaging modalities and the consequent apparent increase in their incidence, and partly by recognition that subtypes based on location or histological appearance define groups with significantly different behaviours. In mid 2012 revised international guidelines for the classification and management of IPMNs and MCNs were published, although in several respects these guidelines represent a consensus view rather than being evidence-based. In recent years major advances in molecular technologies, including whole-exome sequencing, have significantly enhanced our knowledge of pancreatic premalignancy and have identified potentially highly specific diagnostic biomarkers such as mutations in GNAS and RNF43 that could be used to pre-operatively assess pancreatic cysts.

Intraductal tubular neoplasms of the bile ducts

Although most tumors of the bile ducts are predominantly invasive, some have an exophytic pattern within the bile ducts; these intraductal papillary neoplasms usually have well-formed papillae at the microscopic level. In this study, however, we describe a novel type of intraductal neoplasm of the bile ducts with a predominantly tubular growth pattern and other distinctive features. Ten cases of biliary intraductal neoplasms with a predominantly tubular architecture were identified in the files of the Pathology Department at Memorial Sloan-Kettering Cancer Center from 1983 to 2006. For each of these cases we studied the clinical presentation, histologic and immunohistochemical features (9 cases only), and the clinical follow-up of the patients. Three male and 7 female patients (38 to 78 y) presented with obstructive jaundice or abdominal pain. Eight of the patients underwent a partial hepatectomy; 2 underwent a laparoscopic bile duct excision, followed by a pancreatoduodenectomy in one of them. The tumors range in size from 0.6 to 8.0 cm. The intraductal portions of the tumors (8 intrahepatic, 1 extrahepatic hilar, 1 common bile duct) were densely cellular and composed of back-to-back tubular glands and solid sheets with minimal papillary architecture. The cells were cuboidal to columnar with mild to moderate cytologic atypia. Foci of necrosis were present in the intraductal component in 6 cases. An extraductal invasive carcinoma component was present in 7 cases, composing <25% of the tumor in 4 cases, and >75% in 1 case. It was observed by immunohistochemical analysis that the tumor cells expressed CK19, CA19-9, MUC1, and MUC6 in most cases and that SMAD4 expression was retained. MUC2, MUC5AC, HepPar1, synaptophysin, chromogranin, p53, and CA125 were negative in all cases and most were negative for CEA-M and B72.3. Four patients were free of tumor recurrence after 7 to 85 months (average, 27 mo). Four patients with an invasive carcinoma component suffered metastases, 1 after local intraductal recurrence. However, the occurrence of metastasis in 3 of these patients was quite late (average, 52 mo). Intraductal tubular neoplasm of the bile ducts is a biliary intraductal neoplasm with a distinctive histologic pattern resembling the recently described intraductal tubulopapillary neoplasm of the pancreas. Immunohistochemical features are similar to those of other pancreatobiliary-type carcinomas. However, this tumor may be hard to recognize as intraductal because of its complex architecture. When the tumor is entirely intraductal, the outcome appears to be favorable, but metastases can occur when invasive carcinoma is present, even after many years.

Intraductal papillary mucinous neoplasm of the pancreas: an update

Intraductal papillary mucinous neoplasm (IPMN) is a cystic tumor of the pancreas. The etiology is unknown, but increasing evidence suggests the involvement of several tumorigenesis pathways, including an association with hereditary syndromes. IPMN occurs more commonly in men, with the mean age at diagnosis between 64 and 67 years old. At the time of diagnosis, it may be benign, with or without dysplasia, or frankly malignant with an invasive carcinoma. Tumors arising from the main pancreatic duct are termed main-duct IPMNs, those involving the branch ducts, branch-duct IPMNs. In general, small branch-duct IPMNs are benign, particularly in asymptomatic patients, and can be safely followed. In contrast, main-duct tumors should be surgically resected and examined carefully for an invasive component. In the absence of invasion, patient's survival is excellent, from 94 to 100%. For patients with an IPMN-associated invasive carcinoma, the prognosis overall is better than those with a de novo pancreatic ductal adenocarcinoma, with a 5-year survival of 40% to 60% in some series. However, no survival advantage can be demonstrated if the invasive component in an IPMN patient is that of the conventional tubular type (versus mucinous carcinoma). Several histomorphologic variants are recognized, although the clinical significance of this "subtyping" is not well defined.

Diagnostic challenge: intraductal neoplasms of the pancreatobiliary system

To help pathologists avoid misdiagnosis of intraductal neoplasms arising from the pancreatobiliary system, we report two cases that illustrate diagnostic pitfalls. The first is of a 66-year-old man who complained of appetite loss. An early examination led to a diagnosis of intraductal papillary mucinous neoplasm. Macroscopically, a multilocular cyst without visible mucin was identified. Histologically, the compartments consisted of complex fusion of tubular glands surrounded by dilated pancreatic duct. The neoplasm resembled an acinar cell cystadenocarcinoma. However, the neoplastic cells were negative for trypsin. Thus, the final histopathologic diagnosis was an unusual cystic variant of intraductal tubulopapillary neoplasm (ITPN) of the pancreas. The second case is of a 71-year-old man who complained of right upper quadrant pain. Although bile duct stone was suspected, a polypoid nodule was extracted. Histologically, the nodule was composed of tubular glands, with some complex fusion and focal dysplasia, consistent with carcinoma. In addition, lack of MUC-5AC expression led to an initial impression of ITPN of the bile duct. However, the neoplasm showed dysplastic cells based on the columnar cells resembling pyloric glands, indicating the sequential progression. Thus, the final histopathological diagnosis was intraductal papillary neoplasm of the bile duct with high-grade intraepithelial neoplasia. Because phenotypic variants of intraductal neoplasms of the pancreatobiliary system exist, ITPN and ITPN-mimicking tumor must be carefully differentiated from other intraductal neoplasms.

Primary pancreatic cystic neoplasms of the pancreas revisited. Part IV: rare cystic neoplasms

Primary pancreatic cystic neoplasms are being recognized with increasing frequency due to modern imaging techniques. In addition to the more common cystic neoplasms-serous cystadenoma, primary mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm-there are many other less common neoplasms that appear as cystic lesions. These cystic neoplasms include solid pseudopapillary neoplasm of the pancreas (the most common rare cystic neoplasm), cystic neuroendocrine neoplasm, cystic degeneration of otherwise solid neoplasms, and then the exceedingly rare cystic acinar cell neoplasm, intraductal tubular neoplasm, angiomatous neoplasm, lymphoepithelial cysts (not true neoplasms), and few others of mesenchymal origin. While quite rare, the pancreatic surgeon should at the least consider these unusual neoplasms in the differential diagnosis of potentially benign or malignant cystic lesions of the pancreas. Moreover, each of these unusual neoplasms has their own natural history/tumor biology and may require a different level of operative aggressiveness to obtain the optimal outcome.

Intraductal neoplasm of the intrahepatic bile duct: Clinicopathological study of 24 cases

AIM: To investigate the clinicopathological features of intraductal neoplasm of the intrahepatic bile duct (INihB).

METHODS: Clinicopathological features of 24 cases of INihB, which were previously diagnosed as biliary papillomatosis or intraductal growth of intrahepatic biliary neoplasm, were reviewed. Mucin immunohistochemistry was performed for mucin (MUC)1, MUC2, MUC5AC and MUC6. Ki-67, P53 and β-catenin immunoreactivity were also examined. We categorized each tumor as adenoma (low grade), borderline (intermediate grade), and malignant (carcinoma in situ, high grade including tumors with microinvasion).

RESULTS: Among 24 cases of INihB, we identified 24 tumors. Twenty of 24 tumors (83%) were composed of a papillary structure; the same feature observed in intraductal papillary neoplasm of the bile duct (IPNB). In contrast, the remaining four tumors (17%) showed both tubular and papillary structures. In three of the four tumors (75%), macroscopic mucin secretion was limited but microscopic intracellular mucin was evident. Histologically, 16 tumors (67%) were malignant, three (12%) were borderline, and five (21%) were adenoma. Microinvasion was found in four cases (17%). Immunohistochemical analysis revealed that MUC1 was not expressed in the borderline/adenoma group but was expressed only in malignant lesions (P = 0.0095). Ki-67 labeling index (LI) was significantly higher in the malignant group than in the borderline/adenoma group (22.2 ± 15.5 vs 7.5 ± 6.3, P < 0.01). In the 16 malignant cases, expression of MUC5AC showed borderline significant association with high Ki-67 LI (P = 0.0622). Nuclear expression of β-catenin was observed in two (8%) of the 24 tumors, and these two tumors also showed MUC1 expression. P53 was negative in all tumors.

CONCLUSION: Some cases of INihB have a tubular structure, and are subcategorized as IPNB with tubular structure. MUC1 expression in INihB correlates positively with degree of malignancy.

Intraductal papillary-mucinous neoplasia of the pancreas: Histopathology and molecular biology

Intraductal papillary-mucinous neoplasm (IPMN) of the pancreas is a clinically and morphologically distinctive precursor lesion of pancreatic cancer, characterized by gradual progression through a sequence of neoplastic changes. Based on the nature of the constituting neoplastic epithelium, degree of dysplasia and location within the pancreatic duct system, IPMNs are divided in several types which differ in their biological properties and clinical outcome. Molecular analysis and recent animal studies suggest that IPMNs develop in the context of a field-defect and reveal their possible relationship with other neoplastic precursor lesions of pancreatic cancer.

Intraductal tubular neoplasm of the common bile duct

Recently, biliary neoplasms resembling intraductal neoplasms of the pancreas have been documented. In this report, a rare case of intraductal tubular neoplasm (ITN) arising in the common bile duct is presented. A polypoid mass, 10 mm in diameter, was found in a 67-year-old woman in the intrapancreatic part of the common bile duct during the follow up to cholecystolithiasis and choledocholithiasis. Endoscopic polypectomy was performed for the lesion. Histology of the lesion revealed tubular neoplasm, composed of an admixture of tubular glands resembling pyloric gland adenoma with minimal atypia (low-grade tubular adenoma), and those resembling intestinal type tubular adenoma (high-grade tubular adenoma). There was no significant formation of papillae or oncocytic cytoplasm. Small foci of carcinoma in situ of the intestinal type were also observed. On immunostaining low-grade tubular adenoma was positive for MUC5AC and MUC6, and negative for MUC2 and cytokeratin (CK) 20, while high-grade tubular adenoma and carcinoma in situ were positive for MUC2 and CK20, and negative for MUC5AC. Although more case studies of ITN in the biliary tracts are required to clarify the tumorigenesis and pathological features, the lesion may be the biliary counterpart to pancreatic ITN.

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 hepatobiliary 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.

Intraductal oncocytic papillary neoplasms of the pancreas and bile ducts: a description of five new cases and review based on a systematic survey of the literature

BACKGROUND

Intraductal oncocytic papillary neoplasms (IOPN) are rare tumors of the pancreatic and biliary ductal system. It is not absolutely clear if the molecular and clinicopathologic characteristics of IOPN differ significantly from other related lesions, namely intraductal papillary mucinous neoplasms (IPMN). Therefore it is not clear if it is reasonable to consider IOPN as a separate diagnostic and clinical entity.

METHODS

In order to describe the clinicopathologic characteristics of IOPN and to compare them with the IPMN profile, we performed a systematic review of the literature and additionally studied five previously unreported IOPN cases.

RESULTS

IOPN differ from IPMN by lack of K-ras gene mutations in all studied cases. Several differences in the clinical and biological profile between IOPN and IPMN exist, but they are of quantitative rather than of qualitative nature. Additionally, pancreaticobiliary or gastric-foveolar IPMN components may coexist with IOPN component within a single lesion, which suggests at least a partial relation of the pathogenetic pathways of IPMN and IOPN. Importantly, the pathogenesis of accumulation of mitochondria and oxyphilic appearance of IOPN remains unknown.

CONCLUSIONS

At present, there are no reliable criteria other than histopathological picture and K-ras gene status to differentiate IOPN from IPMN. In particular, no clear differences in optimal treatment options and prognosis between these tumors are known. Further studies are needed to clarify the biology of IOPN and to establish their position in clinicopathologic classifications of pancreatic tumors.

Intraductal tubulopapillary neoplasms of the pancreas distinct from pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasms

We have encountered cases of unusual intraductal pancreatic neoplasms with predominant tubulopapillary growth. We collected data on 10 similar cases of "intraductal tubulopapillary neoplasms (ITPNs)" and analyzed their clinicopathologic and molecular features. Tumor specimens were obtained from 5 men and 5 women with a mean age of 58 years. ITPNs were solid and nodular tumors obstructing dilated pancreatic ducts and did not contain any visible mucin. The tumor cells formed tubulopapillae and contained little cytoplasmic mucin. The tumors exhibited uniform high-grade atypia. Necrotic foci were frequently observed, and invasion was observed in some cases. The ITPNs were immunohistochemically positive for cytokeratin 7 and/or cytokeratin 19 and negative for trypsin, MUC2, MUC5AC, and fascin. Molecular studies revealed abnormal expressions of TP53 and SMAD4 in 1 case, but aberrant expression of beta-catenin was not observed. No mutations in KRAS and BRAF were observed in the 8 cases that were examined. Eight patients are alive without recurrence, 1 patient died of liver metastases, and 1 patient is alive but had a recurrence and underwent additional pancreatectomy. The mitotic count and Ki-67 labeling index were significantly associated with invasion. All the features of ITPN were distinct from those of other known intraductal pancreatic neoplasms, including pancreatic intraepithelial neoplasia, intraductal papillary mucinous neoplasm, and the intraductal variant of acinar cell carcinoma. Intraductal tubular carcinomas showed several features that were similar to those of ITPN, except for the tubulopapillary growth pattern. In conclusion, ITPNs can be considered to represent a new disease entity encompassing intraductal tubular carcinoma as a morphologic variant.

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.

[Pancreatic intraductal tubular carcinoma: a sub-group of intraductal papillary-mucinous tumors or a distinct entity? A case report and review of the literature]

We report the case of a 67-year-old man presenting with an isolated 3 cm mass of the pancreatic tail revealed by weight loss. Distal pancreatectomy and splenectomy were performed. Microscopically, the tumor filled the main pancreatic duct, extending into the smaller ducts and was associated with a minor adenocarcinomatous invasive component. The intraductal tumor showed a cribriform pattern, atypical cells without mucus and a MUC1+, MUC2-, MUC5AC- phenotype, all characteristics of intraductal tubular carcinoma, a new entity described by Japanese authors. The differential diagnosis and its relationship with intraductal papillary-mucinous tumors are discussed.

Cystic, mucin-producing neoplasms of the pancreas: the distinguishing features of mucinous cystic neoplasms and intraductal papillary mucinous neoplasms

Perhaps due to the increasing use of sensitive cross-sectional imaging of the abdomen, cystic lesions of the pancreas are being increasingly recognized. In many such cases, biopsy or resection reveals a multilocular cyst lined by columnar mucinous epithelium. Over the past two to three decades, there have been many advances in our understanding of the clinical, pathological, and molecular features of cystic mucin-producing pancreatic neoplasms, most of which are now broadly classified as either mucinous cystic neoplasms (MCNs) or intraductal papillary mucinous neoplasms (IPMNs). Although both share certain histological features and both are regarded to represent preinvasive neoplasms with the potential to progress to invasive carcinoma, there are many significant differences in their pathology and clinical management. The purpose of this review is to highlight the clinical and pathological characteristics of MCNs and IPMNs, with an emphasis of the features that distinguish them and allow proper pathological subclassification.