The Evolving Role of Pathology in New Developments, Classification, Terminology, and Diagnosis of Pancreatobiliary Neoplasms

Oncocytic type has distinct immunohistochemical and recurrence-free survival than other histologic types of the intraductal papillary neoplasm of the bile duct

Although intraductal oncocytic papillary neoplasm (IOPN) was considered distinct from the intraductal papillary neoplasm of the pancreas, the oncocytic histologic type remained as a subtype of intraductal papillary neoplasms of the bile duct (IPNBs) with gastric, intestinal, and pancreatobiliary types based on the fifth edition of the WHO classification. To test the characteristics of the oncocytic type of IPNBs, the histopathologic, immunohistochemical (Hep Par-1 and CD117), and clinical characteristics of 13 oncocytic type were compared with 114 others (15 gastric, 39 pancreatobiliary, and 60 intestinal) IPNB types. The oncocytic type, which occupied about 9% of IPNBs, was more frequent in females (p < 0.05) and larger (mean, 5.3 vs. 3.6 cm; p < 0.002) than other IPNB types. Immunohistochemically, the oncocytic type had more frequent combined Hep Par-1 and CD117 expression than other IPNB types (all p < 0.05). The recurrence-free survival rate for patients with the oncocytic type (5-year survival, 100%) was significantly higher (p = 0.015) than for those with other histologic types (59.9%). The oncocytic type had distinct histopathologic, immunohistochemical, and survival outcomes from other IPNBs. Therefore, it can be separated from other IPNB types and classified as one independent entity, similar to IOPN of the pancreas.

[Histopathologic diagnosis of solid and cystic pancreatic lesions with a focus on ductal adenocarcinoma : A vademecum for daily practice]

Pancreas pathology is constantly evolving and can present various challenges for pathologists. This paper is focused on providing helpful hints for daily routine diagnostics. During histopathological analysis of pancreas biopsies, pancreatic ductal adenocarcinoma must be distinguished not only from other solid neoplasms, but especially from its mimicker, autoimmune pancreatitis. This can be achieved by a systematic workup following clear diagnostic criteria. When analyzing samples from cystic pancreatic lesions, mucin-producing neoplasms must be detected due to their role as pancreatic cancer precursors; molecular analyses can help considerably with their detection and distinction. During frozen section examination, evaluation of the pancreatic neck margin and analysis of unclear lesions of the liver are two important tasks, which are explained further in this article. A special challenge is the evaluation of neoadjuvant treated pancreatic cancer, which requires a detailed macroscopic and microscopic workup. Finally, current advances in precision oncology and emerging approaches for pancreatic cancer within this field are discussed. With the advancement of technical possibilities and their increasingly broad implementation, the classification systems in pancreatic pathology will continue to gain in complexity, but also in accuracy.

Intraductal neoplasms of the pancreatobiliary tract: navigating the alphabet

Cancers of the pancreatobiliary tract are diseases with unfavourable prognoses. In the last couple of decades, two types of lesions have been described as precursors that precede pancreatobiliary cancers. These include incidental microscopic (flat) lesions known as pancreatic intra-epithelial neoplasia and biliary intra-epithelial neoplasia, and grossly visible, mass-forming lesions (tumoral intra-epithelial neoplasia) including intraductal papillary mucinous neoplasms, intraductal oncocytic papillary neoplasms, intraductal tubulopapillary neoplasms, intraductal papillary neoplasms of the bile duct and intracholecystic papillary neoplasms. Early detection and adequate treatment of these precursor lesions, especially the second group, have the potential to prevent pancreatobiliary cancer or at least improve its prognosis. In this review, we discuss their histopathology and recent updates on molecular profiling of these intraductal neoplasms of the pancreatobiliary tract.

Pancreatic Ductal Adenocarcinoma: Molecular Pathology and Predictive Biomarkers

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis due to the lack of methods or biomarkers for early diagnosis and its resistance to conventional treatment modalities, targeted therapies, and immunotherapies. PDACs are a heterogenous group of malignant epithelial neoplasms with various histomorphological patterns and complex, heterogenous genetic/molecular landscapes. The newly proposed molecular classifications of PDAC based on extensive genomic, transcriptomic, proteomic and epigenetic data have provided significant insights into the molecular heterogeneity and aggressive biology of this deadly disease. Recent studies characterizing the tumor microenvironment (TME) have shed light on the dynamic interplays between the tumor cells and the immunosuppressive TME of PDAC, which is essential to disease progression, as well as its resistance to chemotherapy, newly developed targeted therapy and immunotherapy. There is a critical need for the development of predictive markers that can be clinically utilized to select effective personalized therapies for PDAC patients. In this review, we provide an overview of the histological and molecular heterogeneity and subtypes of PDAC, as well as its precursor lesions, immunosuppressive TME, and currently available predictive molecular markers for patients.

Cytopathology of solid pancreatic neoplasms: An algorithmic approach to diagnosis

The classification and management of solid pancreatic neoplasms has expanded significantly in recent years because of advances in immunohistochemical markers, molecular diagnostics, and therapeutics. Solid pancreatic masses are subdivided into 1) ill-defined, scirrhous, and stroma-rich (ductal adenocarcinoma) and 2) well circumscribed, cellular, and stroma-poor (including neuroendocrine neoplasms, acinar cell carcinoma, pancreatoblastoma, and solid-pseudopapillary neoplasm). Definitive diagnosis, particularly of stroma-poor, circumscribed tumors, requires the incorporation of radiologic and cytologic findings, along with the judicious use of (broad, but limited) immunohistochemical panels (pancytokeratin and neuroendocrine [synaptophysin], acinar [trypsin], and solid-pseudopapillary neoplasm [β-catenin] markers), along with unstained slides. Depending on the initial results, immunohistochemical panels should be expanded to include more confirmatory (acinar and neuroendocrine) markers. This ensures that adequate material is available for definitive diagnosis/subclassification and, in some cases, grading, and/or molecular studies, particularly of grade 3 neuroendocrine neoplasms and mixed-lineage tumors. The objective of this review is to expand the understanding of the cytomorphology of solid pancreatic neoplasms using an integrated, multidisciplinary approach in their diagnosis. Knowledge and understanding of recent updates in the classification of solid pancreatic neoplasms ensures that cytopathologists appropriately triage specimens, judiciously use and interpret ancillary studies, and incorporate these results in reporting.

A Review of Mucinous Cystic and Intraductal Neoplasms of the Pancreatobiliary Tract

CONTEXT.—

Although most pancreatic and bile duct neoplasms are solid, mucinous cystic neoplasms and intraductal neoplasms have been increasingly recognized even when clinically silent, thanks to the increased use of sensitive imaging techniques. Cystic and intraductal neoplasms of the pancreas are often resectable and curable and constitute about 5% of all pancreatic neoplasms. Owing to their preinvasive nature and different biology, recognition of these entities remains a major priority. Mucinous cystic neoplasms are histologically and clinically distinct from other cystic pancreatic neoplasms. Pancreatic intraductal neoplasms encompass 3 major entities: intraductal papillary mucinous neoplasm, intraductal oncocytic papillary neoplasm, and intraductal tubulopapillary neoplasm. Intraductal papillary neoplasms of bile ducts are also preinvasive mass-forming neoplasms with both similarities and differences with their pancreatic counterparts. All of these pancreatobiliary neoplasms have diverse and distinctive clinicopathologic, genetic, and prognostic variations.

OBJECTIVE.—

To review the clinical, pathologic, and molecular features of mucinous cystic and intraductal neoplasms of the pancreatobiliary tract.

DATA SOURCES.—

Literature review, diagnostic manuals, and guidelines.

CONCLUSIONS.—

This review will briefly describe well-known clinical and pathologic features and will focus on selected recently described aspects of morphology, grading, classification, and genomic alterations of cystic and intraductal neoplasms of the pancreatobiliary tract.

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas: recommendations for Standardized Imaging and Reporting from the Society of Abdominal Radiology IPMN disease focused panel

There have been many publications detailing imaging features of malignant transformation of intraductal papillary mucinous neoplasms (IPMN), management and recommendations for imaging follow-up of diagnosed or presumed IPMN. However, there is no consensus on several practical aspects of imaging IPMN that could serve as a clinical guide for radiologists and enable future data mining for research. These aspects include how to measure IPMN, define reporting terminology, standardize reporting and unify guidelines for surveillance. The Society of Abdominal Radiology (SAR) created multiple Disease-Focused Panels (DFP) comprised multidisciplinary panel members who focus on a particular disease, with the goal to develop ways for radiologists to improve patient care, education, and research. DFP members met to identify the current controversies and limitations of imaging pancreatic IPMN. This paper aims to provide a practical review of the key imaging characteristics of IPMN for trainees and practicing radiologists, to guide uniformity of performance and interpretation of surveillance imaging studies, and to improve communication with clinicians by providing a lexicon and reporting template based on the experience of the SAR-DFP panel members.

Morphologic changes associated with neoadjuvant-treated pancreatic ductal adenocarcinoma and comparison of two tumor regression grading systems

Pancreatic ductal adenocarcinoma (PDAC) is aggressive, with an overall five-year survival rate of 9%, and few patients are candidates for pancreatectomy at presentation. The role of neoadjuvant therapy (NAT) is evolving, especially for high-risk potentially resectable tumors. Owing to the increasing number of NAT resection specimens, we aim to characterize the histologic changes associated with NAT and to compare two tumor regression grading schemes. One hundred eighteen resections for PDAC were selected from the cases between 2011 and 2018, 59 not treated and 59 treated with NAT. All H&E stained tumor slides were reviewed for histologic changes and graded using the four-tier modified Ryan score (recommended by College of American Pathologists) and the three-tier MD Anderson (MDA) score. The histologic changes evaluated included blue/grey fibrosis, islet cell hyperplasia, dystrophic calcification, amyloid deposition, cholesterol clefts, nerve hypertrophy, elastotic stromal/vascular change, abscess formation, and eosinophilic tumor cell changes. There were statistically significant differences for dystrophic calcification, eosinophilic tumor cell changes, elastotic stromal/vascular change, islet cell hyperplasia, and nerve hypertrophy between the two groups, with these features seen more frequently in NAT cases. Blue/grey stromal fibrosis was present in all cases regardless of NAT, except few complete regression cases and one treated case with intraneural invasion only. Blue/grey fibrosis is a useful histologic visual clue to suggest the possibility of adjacent tumor in the majority of PDAC cases regardless of NAT. By Kaplan-Meier analysis, neither grading scheme correlated with overall survival in our cohort. However, the MDA score was significantly correlated with both time to primary tumor recurrence (p = 0.002) and time to distant recurrence (p = 0.04), whereas the modified Ryan score was not.

Practical Applications of Molecular Testing in the Cytologic Diagnosis of Pancreatic Cysts

Mucinous pancreatic cysts are precursor lesions of ductal adenocarcinoma. Discoveries of the molecular alterations detectable in pancreatic cyst fluid (PCF) that help to define a mucinous cyst and its risk for malignancy have led to more routine molecular testing in the preoperative evaluation of these cysts. The differential diagnosis of pancreatic cysts is broad and ranges from non-neoplastic to premalignant to malignant cysts. Not all pancreatic cysts—including mucinous cysts—require surgical intervention, and it is the preoperative evaluation with imaging and PCF analysis that determines patient management. PCF analysis includes biochemical and molecular analysis, both of which are ancillary studies that add significant value to the final cytological diagnosis. While testing PCF for carcinoembryonic antigen (CEA) is a very specific test for a mucinous etiology, many mucinous cysts do not have an elevated CEA. In these cases, detection of a KRAS and/or GNAS mutation is highly specific for a mucinous etiology, with GNAS mutations supporting an intraductal papillary mucinous neoplasm. Late mutations in the progression to malignancy such as those found in TP53, p16/CDKN2A, and/or SMAD4 support a high-risk lesion. This review highlights PCF triage and analysis of pancreatic cysts for optimal cytological diagnosis.

PCGF3 promotes the proliferation and migration of non-small cell lung cancer cells via the PI3K/AKT signaling pathway

The Polycomb Group Ring Finger 3 (PCGF3) protein has been reported to be significantly upregulated in pancreatic islet tumors and related to signal transduction; however, its detailed mechanisms and biological roles in other tumors, including non-small cell lung cancer (NSCLC), remain unclear. This study investigated the function of PCGF3 in NSCLC and further elucidated its mechanism of action. The immunohistochemical analysis of 86 selected lung cancer tissues revealed that PCGF3 was highly expressed in NSCLC tissues and positively correlated with lymph node metastasis and p-TNM staging. Additionally, PCGF3 promoted cell proliferation in lung cancer by regulating CyclinB1, CyclinD1, and CDK4 expression, and also promoting their migration by regulating RhoA, RhoC, and CDC42. Furthermore, PCGF3 affected both the proliferation and migration of lung cancer cells by regulating the PI3K/AKT pathway, as verified by inhibiting this pathway using LY294002. The findings of this study suggested that PCGF3 is associated with poor prognosis in patients with NSCLC and could therefore be an important biomarker for treating and preventing NSCLC.

Intraductal Oncocytic Papillary Neoplasms: Clinical-Pathologic Characterization of 24 Cases, With An Emphasis on Associated Invasive Carcinomas

BACKGROUND

Intraductal oncocytic papillary neoplasm (IOPN) of the pancreas is a rare tumor. Recent molecular data indicate that it is distinct from other intraductal neoplasms; however, its clinicopathologic characteristics, especially the frequency/significance of an invasive carcinoma component, and biologic behavior remain to be fully defined.

DESIGN

Clinicopathologic characteristics and survival of 24 IOPNs were analyzed. By definition, all tumors exhibited intraductal growth and oncocytic morphology.

RESULTS

The female:male ratio was 1.7, and mean age was 59. In 44% of the patients, the IOPN was discovered incidentally; however, the working diagnosis was "ductal adenocarcinoma" in 42%. Fourteen IOPNs occurred in the head of the pancreas. The median tumor size was 4.5 cm. The tumors often grew along adjacent benign ducts, mimicking invasion, but only 29% exhibited unequivocal invasive carcinoma, mostly in the form of microscopic foci (pT1a=4, pT1b=1, pT2=2), and only 6% had lymph node metastasis. Invasive carcinoma was predominantly composed of small tubular units lined by oncocytic cells, or individual oncocytic cells infiltrating the periductal stroma. Follow-up information was available for 18 patients (median=6.8 y). No patients died from the disease, and the overall 10-year survival was 94%. Patients with invasive carcinoma trended toward a lower 5-year recurrence-free survival than those with noninvasive IOPNs (66% vs. 93%, P=0.066), but overall survival was not impacted by the presence of invasion (P=0.38).

CONCLUSIONS

IOPN is a distinct tumor type in the pancreas. Despite its morphologic complexity and often extensive pagetoid spread to adjacent ducts, conventional invasive carcinoma is seen in only 29% and usually as microscopic foci. Thus, it is not surprising that IOPN exhibits indolent behavior even when invasion is present.

The Diagnostic Yield of Malignancy Comparing Cytology, FISH, and Molecular Analysis of Cell Free Cytology Brush Supernatant in Patients With Biliary Strictures Undergoing Endoscopic Retrograde Cholangiography (ERC): A Prospective Study

BACKGROUND

Routine cytology of biliary stricture brushings obtained during endoscopic retrograde cholangiopancreatography (ERCP) has suboptimal sensitivity for malignancy. We compared the individual and combined ability of cytology, fluorescence in situ hybridization (FISH) analysis and PCR-based mutation profiling (MP) to detect malignancy in standard biliary brushings.

METHODS

We performed a prospective study of patients undergoing ERCP using histology or 1 year follow-up to determine patient outcomes. MP was performed on free-DNA from biliary brushing specimens using normally discarded supernatant fluid. MP examined KRAS point mutations and tumor suppressor gene associated loss of heterozygosity mutations at 10 genomic loci. FISH examined chromosome specific gains or losses.

RESULTS

A total of 101 patients were included in final analysis and 69% had malignancy. Cytology had 26% sensitivity and 100% specificity for malignancy. Using either FISH or MP in combination with cytology increased sensitivity to 44% and 56%, respectively. The combination of all 3 tests (cytology, FISH, and MP) had the highest sensitivity for malignancy (66%). There was no difference in the specificity of cytology, FISH or MP testing when examined alone or in combination. MP improved diagnostic yield of each procedure from 22% to 100%; FISH improved yield to 90%. MP detected 21 malignancies beyond that identified by cytology; FISH detected an additional 13. The combination of FISH and MP testing detected an additional 28 malignancies.

CONCLUSIONS

Both MP and FISH are complimentary molecular tests that can significantly increase detection of biliary malignancies when used in combination with routine cytology of standard biliary brush specimens.

Multi-institutional Validation Study of Pancreatic Cyst Fluid Protein Analysis for Prediction of High-risk Intraductal Papillary Mucinous Neoplasms of the Pancreas

OBJECTIVE

Preliminary work by our group suggested that proteins within the pancreatic cyst fluid (CF) may discriminate degree of IPMN dysplasia. We sought to externally validate these markers and determine whether their inclusion in a preoperative clinical nomogram could increase diagnostic accuracy.

SUMMARY BACKGROUND DATA

IPMN is the most common radiographically identifiable precursor to pancreatic cancer; however, the timing and frequency of its malignant progression are unknown, and there are currently no reliable preoperative tests that can determine the grade of dysplasia in IPMN.

METHODS

Clinical and radiographic data, as well as CF samples, were obtained from 149 patients who underwent resection for IPMN at 1 of 3 institutions. High-risk disease was defined as the presence of high-grade dysplasia or invasive carcinoma. Multianalyte bead array analysis (Luminex) of CF was performed for 4 protein markers that were previously associated with high-risk disease. Logistic regression models were fit on training data, with and without adjustment for a previously developed clinical nomogram and validated with an external testing set. The models incorporating clinical risk score were presented graphically as nomograms.

RESULTS

Within the group of 149 resected patients, 89 (60%) had low-risk disease, and 60 (40%) had high-risk disease. All 4 CF markers (MMP9, CA72-4, sFASL, and IL-4) were overexpressed in patients with high-risk IPMN (P < 0.05). Two predictive models based on preselected combinations of CF markers had concordance indices of 0.76 (Model-1) and 0.80 (Model-2). Integration of each CF marker model into a previously described clinical nomogram leads to increased discrimination compared with either the CF models or nomogram alone (c-indices of 0.84 and 0.83, respectively).

CONCLUSIONS

This multi-institutional study validated 2 CF protein marker models for preoperative identification of high-risk IPMN. When combined with a clinical nomogram, the ability to predict high-grade dysplasia was even stronger.

Imaging and Cytopathological Criteria Indicating Malignancy in Mucin-Producing Pancreatic Neoplasms: A Series of 68 Histopathologically Confirmed Cases

OBJECTIVES

This study aims to evaluate the performance of clinical, imaging, and cytopathological criteria in the identification of high-grade dysplasia/carcinoma (HGD/Ca) in pancreatic mucin-producing cystic neoplasms.

METHODS

Sixty-eight consecutive, histopathologically confirmed mucin-producing cystic neoplasms, evaluated by endoscopic ultrasound-guided fine-needle aspiration, were enrolled; specifically, 39 branch duct intraductal papillary mucinous neoplasms (BD-IPMNs), 21 main duct IPMNs, and 8 mucinous cystic neoplasms. The associations between HGD/Ca in histopathology and findings of endoscopic ultrasound and cytology, demographic, lifestyle, and clinical parameters were evaluated, separately in IPMNs and mucinous cystic neoplasms.

RESULTS

Age 65 years or more was associated with HGD/Ca in IPMNs. In BD-IPMNs, cyst diameter 3 cm or greater (sensitivity, 68.8%; specificity, 65.2%), a mural nodule (sensitivity, 56.3%; specificity, 78.3%), main pancreatic duct diameter 5 to 9 mm (sensitivity, 50.0%; specificity, 87.0%), and suspicious cytology (sensitivity, 81.3%; specificity, 100%) signaled the presence of HGD/Ca. Similarly, in main duct IPMNs, suspicious cytology predicted HGD/Ca with high sensitivity (88.9%) and excellent specificity (100%). Regarding cytopathological criteria, in BD-IPMNs, HGD/Ca was associated with a high nuclear/cytoplasmic ratio, background necrosis, presence of papillary structures, hypochromatic nuclei, hyperchromatic nuclei, and major nuclear membrane irregularities (thickening and/or indentations).

CONCLUSIONS

Clinical, imaging, and cytopathological criteria are useful in the identification of HGD/Ca in IPMNs.

Pancreatic intraepithelial neoplasia in heterotopic pancreas: incidentally diagnosed on endoscopic mucosal resection of a duodenal polyp

Heterotopic pancreas is the presence of pancreatic tissue outside its normal location. It can develop similar pathological conditions that develop in the normal pancreas, including adenocarcinoma and its precursor lesions. Due to the rarity of the condition, the diagnosis can be challenging, and treatment is not well established. ​We present a 47-year-old female patient referred for endoscopic resection of a 2 cm polyp in the second part of her duodenum. Complete endoscopic mucosal resection (EMR) was performed, with pathology revealing low-grade pancreatic intraepithelial neoplasia (PanIN) in heterotopic pancreatic tissue. To the best of our knowledge, this is the first case of heterotopic pancreas with low-grade PanIN in the duodenum to be incidentally diagnosed and treated with EMR.