Surgical interpretation of the WHO subclassification of intrahepatic cholangiocarcinoma: a narrative review.

Intrahepatic cholangiocarcinoma (iCCA) has been subclassified by its gross morphology into the mass-forming (MF), periductal-infiltrating (PI), and intraductal growth (IG) types and their combinations. This classification correlates well with clinical features; for example, MF-iCCA has less lymph-node metastasis and a better prognosis than PI-iCCA. According to the recently accumulated evidence from histological investigations, the WHO classification endorsed a subclassification scheme in which iCCA cases are classified into small- and large-duct types. Small-duct iCCA is considered to originate from septal or smaller bile ducts and is characterized by less frequent lymph-node metastasis, a favorable prognosis, and an MF appearance. Large-duct iCCA arises around the second branch of the biliary tree and has more aggressive biology and distinct genetic abnormalities. According to the practice guidelines for iCCA from the Liver Cancer Study Group of Japan and the National Comprehensive Cancer Network, upfront surgery is recommended for iCCA without distant metastasis regardless of the morphological subtype, based on clinical experience. In consideration of the biological heterogeneity of iCCA, the treatment strategy for iCCA needs to be reconsidered based on the WHO subtypes.

DKK1-CKAP4 signal axis promotes hepatocellular carcinoma aggressiveness.

Hepatocellular carcinoma (HCC) is the most prevalent malignant liver neoplasm. Despite the advances in diagnosis and treatment, the prognosis of HCC patients remains poor. Cytoskeleton-associated membrane protein 4 (CKAP4) is a receptor of the glycosylated secretory protein Dickkopf-1 (DKK1), and the DKK1-CKAP4 axis is activated in pancreatic, lung, and esophageal cancer cells. Expression of DKK1 and CKAP4 has been examined in HCC in independent studies that yielded contradictory results. In this study, the relationship between the DKK1-CKAP4 axis and HCC was comprehensively examined. In 412 HCC cases, patients whose tumors were positive for both DKK1 and CKAP4 had a poor prognosis compared to those who were positive for only one of these markers or negative for both. Deletion of either DKK1 or CKAP4 inhibited HCC cell growth. In contrast to WT DKK1, DKK1 lacking the CKAP4 binding region did not rescue the phenotypes caused by DKK1 depletion, suggesting that binding of DKK1 to CKAP4 is required for HCC cell proliferation. Anti-CKAP4 Ab inhibited HCC growth, and its antitumor effect was clearly enhanced when combined with lenvatinib, a multikinase inhibitor. These results indicate that simultaneous expression of DKK1 and CKAP4 is involved in the aggressiveness of HCC, and that the combination of anti-CKAP4 Ab and other therapeutics including lenvatinib could represent a promising strategy for treating advanced HCC.

[A Case of Ampullary Carcinoma with Celiac Axis Stenosis That Underwent Pancreaticoduodenectomy and Arterial Reconstruction].

A 72-year-old male patient presented with obstructive jaundice and was diagnosed with ampullary carcinoma. Contrast- enhanced computed tomography(CT)showed stenosis of the common hepatic artery and dilatation of the pancreaticoduodenal arcade(PDA)due to celiac axis stenosis(CAS)at the origin, suggesting that hepatic artery blood flow was supplied from the superior mesenteric artery via the PDA. Since calcification of the arterial wall was observed at the origin of the celiac artery(CA), the cause of the CAS was diagnosed as atherosclerotic. An intraoperative gastroduodenal artery(GDA) clamp test showed no obvious decrease in hepatic arterial blood flow. However, because of concerns about the postoperative patency of the CA, an inferior pancreaticoduodenal artery-GDA bypass using the left great saphenous vein and subtotal stomach-preserving pancreaticoduodenectomy were performed. The postoperative course was uneventful. When pancreaticoduodenectomy is performed in patients with atherosclerotic CAS, this arterial reconstruction method can be considered as an option.

A good surgical field for para-aortic nodal dissection in gastric cancer by the Cattell-Braasch maneuver.

PURPOSE: Gastric cancer patients with para-aortic lymph node metastases may achieve long-term survival with radical gastrectomy and para-aortic lymph nodal dissection (PAND) following neoadjuvant therapy. We introduced the Cattell-Braasch maneuver to facilitate safe and complete PAND for advanced gastric cancer with extensive lymph node metastases. METHODS: Between January 2014 and March 2020, 7 patients with highly advanced gastric cancer received preoperative chemotherapy followed by radical gastrectomy and PAND using the Cattell-Braasch maneuver. This maneuver consists of mobilization of the right hemi-colon and the total small intestine. RESULTS: Five patients received preoperative chemotherapy for para-aortic lymph node metastases and 2 for bulky lymph node metastases around the supra-pancreatic area. All patients received S-1 + cisplatin therapy, and one was additionally treated with paclitaxel chemotherapy followed by nivolumab. After chemotherapy, 2 patients with para-aortic lymph node metastases achieved down-staging on imaging tests. Total gastrectomy with PAND by the Cattell-Braasch maneuver was performed on all patients and was accompanied by splenectomy (n = 5) and distal pancreatectomy (n = 1). Pathological assessments revealed that 3 patients had para-aortic lymph node metastases, and the median number of retrieved para-aortic lymph nodes was 16. Three patients without para-aortic lymph node metastasis survived for more than 5 years without recurrence. CONCLUSION: The Cattell-Braasch maneuver provides a good surgical field and is useful for complete PAND for gastric cancer.

Anatomical change of SMV branches after the Cattell Braasch maneuver facilitates safe resection around the uncinated process in pancreatoduodenectomy.

BACKGROUND: The aims of the present study were to demonstrate the anatomical change of superior mesenteric vein (SMV) branches and to show how the Cattell Braasch maneuver facilitates a safer ligation of these venous branches during a pancreatoduodenectomy (PD). METHODS: Between January 2010 and December 2019, 97 patients with peripancreatic tumors underwent pancreatectomy. We retrospectively reviewed preoperative triple-phase enhanced computed tomography (CT) images and analyzed variations in SMV branches. Anatomical changes in SMV branches after the Cattell Braasch technique were observed using our operation video and illustrations. RESULTS: The first jejunal vein (J1v) in 75% of patients ran posterior to the superior mesenteric artery (SMA), while the remainder (25%) ran anterior to it. The inferior pancreatoduodenal vein (IPDV) was preoperatively detected in 91% of patients. The IPDV drained into the J1v in 74% of patients and into the SMV in 37%. After the Cattell Braasch maneuver, the J1v which ran posterior to the SMA now was found to lie to the right anterolateral side the SMA and the visualization of both the J1v and the IPDV were much more clearly visualized. CONCLUSIONS: The most frequent venous variation was the IPDV draining into the J1v posterior to the SMA. After the Cattell Braasch maneuver, the IPDV was now located to the right anterolateral anterior aspect of the SMA which facilitates its visualization and should allow a safer ligation.

Biliary intraductal tubule-forming neoplasm: a whole exome sequencing study of MUC5AC-positive and -negative cases.

AIMS: Biliary intraductal tubular neoplasms that are non-mucinous and negative for mucin 5AC (MUC5AC) are called intraductal tubulopapillary neoplasms (ITPNs). Intraductal tubular neoplasms with mucinous cytoplasm and MUC5AC positivity also occur and their nature remains unclear, although some pathologists may classify these as 'intraductal papillary neoplasms of the bile duct (IPNBs) of gastric type'. This study aimed to elucidate genetic features of biliary intraductal tubular neoplasms. METHODS AND RESULTS: Six resected cases of biliary intraductal neoplasm with >70% tubular configuration were characterised by clinicopathological examination and whole exome sequencing, and the findings obtained were compared between MUC5AC-negative (n = 2) and -positive cases (n = 4). The intraductal tumours consisted of the pancreatobiliary-type epithelium with high-grade dysplasia arranged in back-to-back tubules. Both of the two MUC5AC-negative cases were non-invasive neoplasms and developed in the liver, whereas all MUC5AC-positive cases had invasive carcinoma and were present in the intrahepatic (n = 2), perihilar (n = 1) and distal bile ducts (n = 1). In an exome-sequencing study, MUC5AC-negative cases harboured mutations in CTNNB1, SF3B1, BAP1 and BRCA1 (one case each). KRAS mutations were observed in three of four MUC5AC-positive cases (75%) but none of the MUC5AC-negative neoplasms. Compared to published data, known driver genes of other intraductal neoplasms of the pancreatobiliary system (e.g. APC, CTNNB1, STK11, GNAS and PIK3CA) were wild-type in all but one MUC5AC-negative case with CTNNB1 mutation. Chromatin modifiers (ARID1A, BAP1 and KMT2C) were also altered in MUC5AC-positive cases, similar to usual cholangiocarcinomas. CONCLUSIONS: This exome-sequencing study suggested that MUC5AC-negative biliary ITPNs are genetically distinct from pancreatic ITPNs and IPNBs. They may also biologically differ from MUC5AC-positive tubular neoplasms despite morphological resemblance.

Predictors of postoperative early recurrence of extrahepatic bile duct cancer.

PURPOSES: Resected bile duct cancers often relapse during postoperative follow-up. The aim of this study was to detect predictors of early recurrence in patients with extrahepatic bile duct cancer. METHODS: Consecutive cases (n = 162) of extrahepatic bile duct cancer in which R0 or R1 resection was achieved in Kobe University Hospital between 2000 and 2016 were divided into three groups [early recurrence (ER), within 6 months of surgery, late recurrence (LR), and no recurrence (NR)] and their clinicopathological features were compared. RESULTS: Twenty-two patients (14%) developed ER and 69 (43%) developed LR after surgery. The rates of lymph node metastasis and residual cancer status were similar in all three groups. Liver metastasis was more common in the ER group than in the LR group (59% vs. 32%, p = 0.02). ER had a significantly worse prognosis than LR and NR (7% vs. 44% vs. 85% at 1 year, p < 0.01, respectively). Multivariate analysis showed that age > 75 years, serum CA19-9 > 1008 U/ml and perineural invasion were independent predictors of early recurrence. CONCLUSIONS: High serum CA19-9 values (> 1008 U/ml) were an independent predictor of early recurrence. Neoadjuvant therapy and aggressive adjuvant therapy may be beneficial for patients who show highly elevated CA19-9 values before surgery.

Benefits and limitations of middle bile duct segmental resection for extrahepatic cholangiocarcinoma.

BACKGROUND: Pancreaticoduodenectomy (PD) is a standardized strategy for patients with middle and distal bile duct cancers. The aim of this study was to compare clinicopathological features of bile duct segmental resection (BDR) with PD in patients with extrahepatic cholangiocarcinoma. METHODS: Consecutive cases with extrahepatic cholangiocarcinoma who underwent BDR (n = 21) or PD (n = 84) with achievement of R0 or R1 resection in Kobe University Hospital between January 2000 and December 2016 were enrolled in the present study. RESULTS: Patients who underwent PD were significantly younger than those receiving BDR. The frequency of preoperative jaundice, biliary drainage and cholangitis was not significantly different between the two groups. The duration of surgery was longer and there was more intraoperative bleeding in the PD than in the BDR group (553 vs. 421 min, and 770 vs. 402 mL; both P<0.01). More major complications (>Clavien-Dindo IIIa) were observed in the PD group (46% vs. 10%, P<0.01). Postoperative hospital stay was also longer in that group (30 vs. 19 days, P = 0.02). Pathological assessment revealed that tumors were less advanced in the BDR group but the rate of lymph node metastasis was similar in both groups (33% in BDR and 48% in PD, P = 0.24). The rate of R0 resection was significantly higher in the PD group (80% vs. 38%, P<0.01). Adjuvant chemotherapy was more frequently administered to patients in the BDR group (62% vs. 38%, P = 0.04). Although 5-year overall survival rates were similar in both groups (44% for BDR and 51% for PD, P = 0.72), in patients with T1 and T2, the BDR group tended to have poorer prognosis (44% vs. 68% at 5-year, P = 0.09). CONCLUSIONS: BDR was comparable in prognosis to PD in middle bile duct cancer. Less invasiveness and lower morbidity of BDR justified this technique for selected patients in a poor general condition.

Keratin 19-expressing hepatocellular carcinoma and small-duct type intrahepatic cholangiocarcinoma show a similar postoperative clinical course but have distinct genetic features.

AIMS: The present study aimed to systematically compare clinicopathological and genetic features between keratin 19 (K19)-expressing hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). METHODS AND RESULTS: Consecutive cases of HCC (n = 430) were classified into K19+ and K19- using immunohistochemistry. ICCA cases were also separated into small-(S-iCCA; n = 36) and large-duct types (n = 22) based on recently proposed criteria, with the former being used in the present study. Mutational hot-spots in TERT, CTNNB1, KRAS and IDH1 were sequenced. Twenty-six cases (6%) of HCC expressed K19. K19+ HCC was more strongly associated with chronic hepatitis B than K19- HCC and S-iCCA (46% versus 17% and 6%; both P < 0.001). Lymph node metastasis was observed in K19+ HCC (8%) and S-iCCA (22%), but was exceptional in K19- HCC (1%). K19+ HCC had TERT promoter mutations less frequently than K19- HCC (31% versus 59%; P = 0.022), and lacked alterations in KRAS and IDH1. CTNNB1 mutations were similarly observed in K19+ and K19- HCC (23% and 19%, respectively), but rare in S-iCCA (3%). The postoperative survival curve of K19+ HCC was almost identical to that of S-iCCA in the first 5 years (approximately 50% at 5 years), and significantly worse than that of K19- HCC (P = 0.040). Extrahepatic recurrence was more common in K19+ HCC (50%) and S-iCCA (35%) than in K19- HCC (15%) (P = 0.001). CONCLUSIONS: Although K19+ HCC and S-iCCA showed similar biological behaviours, they did not share any driver gene mutations, suggesting the possible involvement of epigenetic alterations in the iCCA-like features of K19+ HCC.

IL-33 overexpression in gallbladder cancers associated with pancreatobiliary maljunction.

AIMS: To investigate whether genetic or inflammatory pro-oncogenic factors are relevant to the increased risk of gallbladder cancers in patients with pancreaticobiliary maljunction (PBM). METHODS AND RESULTS: Mutations in KRAS exon 2 were examined by a highly sensitive, droplet digital PCR platform using surgically resected specimens of PBM-associated (n = 31) and non-associated gallbladder cancers (n = 49). The tissue expression of IL-6 and IL-33, which are suspected to promote biliary carcinogenesis, was analysed by quantitative real-time PCR and in-situ hybridisation. The incidence of KRAS mutations was similarly low in PBM-associated (five of 32 cases; 16%) and non-associated cancers (four of 49 cases; 8%) (P = 0.272). The tissue expression of IL-33 mRNA, but not IL-6 mRNA, was significantly higher in PBM-associated gallbladder cancers than in gallbladder cancers without PBM (P = 0.004). A similar degree of IL-33 overexpression was also observed in the background non-cancerous mucosa in cases of PBM-associated gallbladder cancers, and was significantly greater than that in PBM cases with cholecystitis alone (P < 0.001). The results of in-situ hybridisation indicated that the source of IL-33 production in PBM-associated carcinomas was the endothelium, cancer cells and non-neoplastic biliary epithelium. In a combined PBM-associated and non-associated cohort, IL-33 overexpression in gallbladder cancers correlated with less aggressive features (e.g. a lower pT stage and longer overall survival), similar to recently reported findings on large-duct cholangiocarcinomas. CONCLUSIONS: KRAS mutations do not appear to be associated with a high risk of malignancy in PBM, while IL-33 overexpression may provide a pro-oncogenic microenvironment in the gallbladder mucosa of patients with PBM.

Histological and molecular characterization of intrahepatic bile duct cancers suggests an expanded definition of perihilar cholangiocarcinoma.

BACKGROUND: Growing evidence has suggested that intrahepatic cholangiocarcinoma (iCCA) can be classified into small- and large-duct types. The present study aimed to elucidate how large-duct iCCA is similar and dissimilar to perihilar cholangiocarcinoma (pCCA). METHODS: The study cohort consisted of iCCA (n = 58) and pCCA (n = 44). After iCCA tumors were separated into small- (n = 36) and large-duct (n = 22) types based on our histologic criteria, genetic statuses of the three types of neoplasms were compared. Locations of iCCA were plotted on a three-dimensional image and their distances from the portal bifurcation were measured. RESULTS: Large-duct iCCA was distinct from small-duct iCCA in terms of frequency of bile duct reconstruction required, perineural infiltration, and survival, with these features more similar to pCCA. Large-duct iCCA and pCCA more frequently had the loss of SMAD4 expression and MDM2 amplifications than small-duct iCCA, whereas the loss of BAP1 expression and IDH1 mutations were mostly restricted to small-duct iCCA. From imaging analysis, most tumors of large-duct iCCA were present around the second branches of the portal vein. CONCLUSION: Large-duct type iCCA shared the molecular features with pCCA, and it may be reasonable to expand the definition of pCCA to include cancers originating from the second bile duct branches.

[Analysis of Surgical Resection for Elderly Patients with Biliary Tract Cancer].

Although surgical resection is the first-line treatment for biliary tract cancer(BTC), elderly patients often have underlying diseases and decreased cardiopulmonary function that place them at a high risk of undergoing surgery. We examined the safety and efficacy of surgical resection in elderly BTC patients. Among the BTC cases that underwent surgical resection at Kobe University Hospital from 2009 to 2015, the safety and prognosis ofthose aged 75 years or older(Group 1)were compared to those younger than 75 years(Group 2)at the time ofsurgery. Fifty-two patients with perihilar cholangiocarcinoma( Bp), 29 patients with intrahepatic cholangiocarcinoma(ICC), and 40 patients with ampulla ofVater cancer(AV) were included. There was no significant difference between the 2 groups with respect to complications of Grade Ⅲor above, while surgery-related death was more common in Bp and ICC ofGroup 1. The median survival ofGroup 1 following hepatectomy for Bp and ICC(22 months)was significantly shorter than that of Group 2(40 months)(p=0.023). There was no significant difference in overall survival of Group 1 and Group 2 patients with AV(p=0.094). Surgical resection for BP and ICC for elderly patients has a higher risk of hepatectomy; therefore, precise assessment of oncologic and patient risk factors should be performed. As we can expect to achieve similar prognoses between non-elderly and elderly patients with AV, aggressive treatments should be considered for elderly patients with AV.

[A Case of Conversion Surgery Following Chemotherapy in Initially Unresectable Locally Advanced Gallbladder Carcinoma].

A 47-year-old woman who had unresectable locally advanced gallbladder cancer(GBC)accompanied with liverinvasion, duodenum invasion, transverse colon invasion, and surrounding lymphatic metastasis received 5 courses of chemotherapy with gemcitabine plus cisplatin. Afterthe chemotherapy, imaging showed down-staging of the GBC, indicating tumor shrinkage. The initial laparoscopic examination revealed no peritoneal seeding or distant metastasis. Subsequently, we performed cholecystectomy with a partial hepatectomy at the gallbladder bed. Malignant findings were not observed in the histopathological examination and the pathological diagnosis was CR with pT0N0M0, Stage 0. The patient was discharged on day 11 after the operation. There has been no recurrence at 14 months after surgery. Although the prognosis of advanced GBC with local invasion is generally poor, chemotherapy might be an effective treatment for patients with initially unresectable locally advanced gallbladder carcinoma.

SOX2-silenced squamous cell carcinoma: a highly malignant form of esophageal cancer with SOX2 promoter hypermethylation.

This study originally aimed to investigate whether the overexpression of SOX2 is associated with the poor prognosis of patients with squamous cell carcinoma of the esophagus. However, we unexpectedly found that esophageal squamous cell carcinomas completely lacking SOX2 expression showed distinct pathologic features and highly aggressive clinical courses. The study cohort consisted of 113 consecutive patients with esophageal squamous cell carcinoma who underwent surgical resection without neoadjuvant therapy. Immunostaining on tissue microarrays and whole sections revealed that 8/113 (7%) cases were entirely negative for this transcriptional factor. SOX2-negative cancers were histologically less differentiated (P=0.002) and showed higher pT and pStages (P=0.003 and 0.007, respectively) than SOX2-positive cases. A remarkable finding was widespread lymphatic infiltration distant from the primary invasive focus, which was observed in 4 SOX2-negative cancers (50%), but none of the SOX2-positive cases. All separate dysplastic lesions observed in SOX2-negative cases were also SOX2-negative. The negative expression of SOX2 appeared to be an independent poor prognostic factor (OR=7.05, 95% CI=1.27-39.0). No mutations were identified in the coding or non-coding regions of SOX2. Fluorescent in situ hybridization did not show any copy-number variations in this gene. Since the SOX2 promoter contains an extensive CpG island, SOX2-negative cases underwent methylation-specific PCR, which disclosed promoter hypermethylation in all cases. In conclusion, SOX2-silenced squamous cell carcinomas of the esophagus appear to be a minor, but distinct form of malignancy characterized by extensive lymphatic invasion, a poor prognosis, and potential association with multiple SOX2-negative neoplastic lesions. The hypermethylation of the promoter region is seemingly a critical epigenetic event leading to SOX2 silencing.

Serum Elastase 1 Level as a Risk Factor for Postoperative Recurrence in Patients with Well-Differentiated Pancreatic Neuroendocrine Neoplasms.

PURPOSE: This study was designed to assess the potential role of the preoperative serum level of elastase 1 as a risk factor for recurrence in patients with resectable well-differentiated pancreatic neuroendocrine neoplasms (PanNETs). METHODS: Preoperative serum elastase 1 levels were measured in 53 patients with PanNETs who underwent complete tumor resection in two tertiary referral centers between January 2004 and June 2017. The preoperative elastase 1 levels were correlated with clinicopathological characteristics, including tumor recurrence and recurrence-free survival. RESULTS: The median elastase 1 level was 96 ng/dL (range: 21-990 ng/dL). Preoperative serum elastase 1 levels were significantly higher in those with tumors ≥ 20 mm in diameter (vs. < 20 mm, P = 0.018), WHO grade 2 (vs. grade 1, P = 0.035), and microscopic venous invasion (vs. without venous invasion, P = 0.039). The median preoperative serum level of elastase 1 was higher in patients with recurrence than in those without recurrence (251 vs. 80 ng/dL, P = 0.004). Receiver operating characteristic analysis of elastase 1 levels showed that a cutoff level of 250 ng/dL was associated with postoperative recurrence, with 63% sensitivity, 100% specificity, and 94% overall accuracy. Patients with higher elastase 1 levels showed significantly worse recurrence-free survival than that of those with lower levels (2-year recurrence-free survival rate: 25% and 92%, respectively, P < 0.001). CONCLUSIONS: Our data provide the first evidence that high preoperative elastase 1 levels may be a risk factor for postoperative recurrence in patients with resectable PanNETs.

Interleukin-33 overexpression reflects less aggressive tumour features in large-duct type cholangiocarcinomas.

AIMS: The aim of the present study was to elucidate the clinicopathological significance of interleukin (IL)-6 and IL-33 expression in intrahepatic cholangiocarcinomas (iCCAs) and perihilar cholangiocarcinomas (pCCAs). METHODS AND RESULTS: IL-6 and IL-33 mRNA expression levels were examined in iCCAs (n = 55) and pCCAs (n = 32) by the use of quantitative real-time polymerase chain reaction and a highly sensitive in-situ hybridisation protocol (RNAscope), and expression levels were correlated with clinicopathological features. According to a recently proposed classification scheme, iCCAs were separated into small-duct (n = 33) and large-duct (n = 22) types. IL-6 and IL-33 expression levels were higher in large-duct iCCAs and pCCAs than in small-duct iCCAs, and there was a positive correlation between the expression levels of these cytokines. Double in-situ hybridisation/immunostaining showed that IL-6 mRNA was expressed in actin-positive (myo)fibroblasts, whereas IL-33 mRNA was mainly produced by CD31-positive endothelial cells. With the average expression level as a cut-off point, cases were classified as IL-6high and IL-6low or IL-33high and IL-33low . In the combined cohort of large-duct iCCAs and pCCAs, IL-6high and IL-6low cholangiocarcinomas shared many features, whereas IL-33high cases had less aggressive characteristics than IL-33low cases, as shown by lower tumour marker concentrations, smaller tumour sizes, less common vascular invasion, lower pT stages, and higher lymphocyte/monocyte ratios in blood. KRAS mutations were slightly less common in IL-33high cases than in IL-33low cases (9% versus 29%; P = 0.061). The strong expression of IL-33 in tissue appeared to be an independent favourable prognostic factor. CONCLUSIONS: IL-33high cholangiocarcinomas may represent a unique, less aggressive carcinogenetic process of the large bile ducts.

High-grade PanIN presenting with localised stricture of the main pancreatic duct: A clinicopathological and molecular study of 10 cases suggests a clue for the early detection of pancreatic cancer.

AIMS: This study aimed to identify the pathological features of high-grade PanIN that presents with imaging-detectable abnormalities. METHODS AND RESULTS: Ten cases of isolated, main-duct, high-grade PanIN as the primary clinical presentation were identified. All patients presented with stenosis of the main pancreatic duct, with two being associated with extensive upstream duct dilatation (>5 mm in diameter). Pancreatic juice cytology suggested adenocarcinoma in all seven cases examined. In resected specimens, high-grade PanIN was present chiefly in the main pancreatic duct, with longitudinal extension ranging between 3 and 40 mm in length (median = 18 mm). In four cases, in which hypoechoic or hypovascular masses were observed on imaging, radiopathology correlations suggested that they represented parenchymal atrophy and subsequent fibrosis around affected ducts, but not invasive malignancy. On immunohistochemistry, the loss of p16 expression was found in five (50%), p53 overexpression in two (20%) and loss of SMAD4 expression in none (0%). KRAS mutations were detected in nine cases, with two dominant clones being found in three by ultrasensitive droplet digital polymerase chain reaction, suggesting the genetic heterogeneity of dysplastic cells composing individual lesions. Mutant GNAS was also observed in one case. CONCLUSIONS: Isolated high-grade PanIN may present with pancreatic duct stenosis. Therefore, intensive investigations including pancreatic juice cytology will be required for patients with unexplained pancreatic duct stenosis. The abnormal expression of p53 and SMAD4 is infrequent, while GNAS may be mutated in premalignant lesions mainly affecting the main pancreatic duct, similar to KRAS.

Dichotomy in intrahepatic cholangiocarcinomas based on histologic similarities to hilar cholangiocarcinomas.

Intrahepatic cholangiocarcinomas were classified into two types based on their microscopic appearance. Tumors with histologic similarities to hilar cholangiocarcinomas (predominantly ductal adenocarcinomas with minor tubular components, if present, restricted to the invasive front) were defined as the perihilar type, whereas the others were classified as peripheral cholangiocarcinomas. Among the 47 cases examined in the present study, 26 (55%) were classified as the perihilar type, whereas 21 (45%) were the peripheral type. The perihilar type had higher pT stages and more frequently showed a periductal-infiltrating gross appearance and microscopic perineural infiltration than peripheral cholangiocarcinomas. The presence of low-grade biliary intraepithelial neoplasia in the adjacent bile ducts was only found in perihilar cholangiocarcinomas (6/21, 29%). The immunophenotype also differed between the two types with MUC5AC and MUC6 being more commonly expressed in the perihilar type. One-third of perihilar cholangiocarcinomas lacked the expression of SMAD4, suggesting SMAD4 mutations, whereas the loss of BAP1 expression and IDH1 mutations were almost restricted to the peripheral type (35 and 15%, respectively). Patients with perihilar cholangiocarcinoma had worse overall survival than those with peripheral cancer (P=0.027). A multivariate analysis identified the histologic classification as an independent prognostic factor (P=0.005, HR=3.638). Comparisons between intrahepatic and hilar cholangiocarcinomas also revealed that the molecular features and prognosis of perihilar cholangiocarcinomas were very similar to those of hilar cholangiocarcinomas. In conclusion, this histology-based classification scheme of intrahepatic cholangiocarcinomas will be useful and clinically relevant because it represents different underlying molecular features and has an independent prognostic value.

Mucinous cystic neoplasms of the liver and pancreas: relationship between KRAS driver mutations and disease progression.

AIMS: To compare the oncogenic mutation status among mucinous cystic neoplasms (MCNs) of different histological grades and between liver and pancreatic MCNs. METHODS AND RESULTS: KRAS, GNAS, RNF43 and PIK3CA were sequenced in 25 surgical cases of hepatopancreatic MCN. Molecular features were correlated with clinicopathological and immunohistochemical findings. KRAS mutations were identified in five cases (20%), whereas GNAS, RNF43 and PIK3CA were wild-type in all cases. KRAS mutations were uncommon in cases of low-grade dysplasia (1/20, 5%), whereas KRAS was mutated in all cases of higher grades, except for one liver MCN with intermediate-grade dysplasia (4/5, 80%; P = 0.002). This genetic alteration was slightly more frequent in the pancreas than in the liver [4/17 (24%) versus 1/8 (13%), P = not significant]. KRAS-mutated MCNs more commonly had a multilocular cystic appearance (P = 0.040) and expression of mucin (MUC) 1 (P = 0.040), MUC2 (P = 0.016) and MUC5AC (P = 0.015) than KRAS-wild-type tumours. In cases of KRAS-mutated MCNs with intermediate-grade or high-grade dysplasia, identical mutations were also detected in areas of adjacent low-grade dysplasia. CONCLUSIONS: KRAS mutations appear to be major driver genetic alterations in both liver and pancreatic MCNs. As identical KRAS mutations were present in low-grade and higher-grade areas in individual cases, KRAS mutations occurring in low-grade MCNs may lead to tumour progression. Thus, preoperative KRAS testing may contribute to estimations of malignant potential. The lower incidence of KRAS mutations in liver MCNs may also explain why the risk of malignant transformation in liver MCNs is lower than that in pancreatic MCNs.

Comparative clinicopathological study of biliary intraductal papillary neoplasms and papillary cholangiocarcinomas.

AIMS: The aim of this study was to achieve a better definition of intraductal papillary neoplasms of the bile duct (IPNBs). METHODS AND RESULTS: Biliary tumours that showed predominantly intraductal papillary growth were provisionally classified as IPNBs (n = 25) and papillary cholangiocarcinomas (n = 27). IPNB was defined as a neoplasm that is confined to the epithelium or is regularly arranged in a high-papillary architecture along thin fibrovascular stalks, whereas the term 'papillary cholangiocarcinoma' was used for tumours with more complex papillary structures (e.g. irregular papillary branching or mixed with solid-tubular growth). In our consecutive cohort of biliary neoplasms, 5% were classified as IPNBs, and 10% as papillary cholangiocarcinomas. IPNBs differed from papillary cholangiocarcinomas by less advanced invasion, gross mucin overproduction (72% versus 7%), and their prevalent location (84% of IPNBs in intrahepatic/hilar ducts; 70% of papillary cholangiocarcinomas in extrahepatic ducts). Gastric-type and oncocytic-type tumours were only detected in IPNBs. Expression of mucin core proteins and cytokeratin 20 significantly differed between the two groups. KRAS and GNAS were wild-type genotypes in all but one case of KRAS-mutated IPNB. Patients with IPNB had better recurrence-free survival than those with papillary cholangiocarcinoma (P = 0.007). In multivariate analysis, in which several other prognostic factors (e.g. stromal invasion and lymph node metastasis) were applied, the classification of the two papillary tumours was an independent prognostic factor (P = 0.040). CONCLUSIONS: Given the significant contrast in clinicopathological features between IPNBs and papillary cholangiocarcinomas, it may be more appropriate to use the diagnostic term 'IPNB' for selected tumours that show regular papillary growth, separately from papillary cholangiocarcinomas.