Three-dimensional assessments are necessary to determine the true, spatially-resolved composition of tissues.

Methods for spatially resolved cellular profiling using thinly cut sections have enabled in-depth quantitative tissue mapping to study inter-sample and intra-sample differences in normal human anatomy and disease onset and progression. These methods often profile extremely limited regions, which may impact the evaluation of heterogeneity due to tissue sub-sampling. Here, we applied CODA, a deep learning-based tissue mapping platform, to reconstruct the three-dimensional (3D) microanatomy of grossly normal and cancer-containing human pancreas biospecimens obtained from individuals who underwent pancreatic resection. To compare inter- and intra-sample heterogeneity, we assessed bulk and spatially resolved tissue composition in a cohort of two-dimensional (2D) whole slide images (WSIs) and a cohort of thick slabs of pancreas tissue that were digitally reconstructed in 3D from serial sections. To demonstrate the marked under sampling of 2D assessments, we simulated the number of WSIs and tissue microarrays (TMAs) necessary to represent the compositional heterogeneity of 3D data within 10% error to reveal that tens of WSIs and hundreds of TMA cores are sometimes needed. We show that spatial correlation of different pancreatic structures decay significantly within a span of microns, demonstrating that 2D histological sections may not be representative of their neighboring tissues. In sum, we demonstrate that 3D assessments are necessary to accurately assess tissue composition in normal and abnormal specimens and in order to accurately determine neoplastic content. These results emphasize the importance of intra-sample heterogeneity in tissue mapping efforts.

Somatic loss of ATM is a late event in pancreatic tumorigenesis.

Understanding the timing and spectrum of genetic alterations that contribute to the development of pancreatic cancer is essential for effective interventions and treatments. The aim of this study was to characterize somatic ATM alterations in noninvasive pancreatic precursor lesions and invasive pancreatic adenocarcinomas from patients with and without pathogenic germline ATM variants. DNA was isolated and sequenced from the invasive pancreatic ductal adenocarcinomas and precursor lesions of patients with a pathogenic germline ATM variant. Tumor and precursor lesions from these patients as well as colloid carcinoma from patients without a germline ATM variant were immunolabeled to assess ATM expression. Among patients with a pathogenic germline ATM variant, somatic ATM alterations, either mutations and/or loss of protein expression, were identified in 75.0% of invasive pancreatic adenocarcinomas but only 7.1% of pancreatic precursor lesions. Loss of ATM expression was also detected in 31.0% of colloid carcinomas from patients unselected for germline ATM status, significantly higher than in pancreatic precursor lesions [pancreatic intraepithelial neoplasms (p = 0.0013); intraductal papillary mucinous neoplasms, p = 0.0040] and pancreatic ductal adenocarcinoma (p = 0.0076) unselected for germline ATM status. These data are consistent with the second hit to ATM being a late event in pancreatic tumorigenesis. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Uncovering the spatial landscape of molecular interactions within the tumor microenvironment through latent spaces.

Recent advances in spatial transcriptomics (STs) enable gene expression measurements from a tissue sample while retaining its spatial context. This technology enables unprecedented in situ resolution of the regulatory pathways that underlie the heterogeneity in the tumor as well as the tumor microenvironment (TME). The direct characterization of cellular co-localization with spatial technologies facilities quantification of the molecular changes resulting from direct cell-cell interaction, as it occurs in tumor-immune interactions. We present SpaceMarkers, a bioinformatics algorithm to infer molecular changes from cell-cell interactions from latent space analysis of ST data. We apply this approach to infer the molecular changes from tumor-immune interactions in Visium spatial transcriptomics data of metastasis, invasive and precursor lesions, and immunotherapy treatment. Further transfer learning in matched scRNA-seq data enabled further quantification of the specific cell types in which SpaceMarkers are enriched. Altogether, SpaceMarkers can identify the location and context-specific molecular interactions within the TME from ST data.

TSPAN6 is a suppressor of Ras-driven cancer.

Oncogenic mutations in the small GTPase RAS contribute to ~30% of human cancers. In a Drosophila genetic screen, we identified novel and evolutionary conserved cancer genes that affect Ras-driven tumorigenesis and metastasis in Drosophila including confirmation of the tetraspanin Tsp29Fb. However, it was not known whether the mammalian Tsp29Fb orthologue, TSPAN6, has any role in RAS-driven human epithelial tumors. Here we show that TSPAN6 suppressed tumor growth and metastatic dissemination of human RAS activating mutant pancreatic cancer xenografts. Whole-body knockout as well as tumor cell autonomous inactivation using floxed alleles of Tspan6 in mice enhanced KrasG12D-driven lung tumor initiation and malignant progression. Mechanistically, TSPAN6 binds to the EGFR and blocks EGFR-induced RAS activation. Moreover, we show that inactivation of TSPAN6 induces an epithelial-to-mesenchymal transition and inhibits cell migration in vitro and in vivo. Finally, low TSPAN6 expression correlates with poor prognosis of patients with lung and pancreatic cancers with mesenchymal morphology. Our results uncover TSPAN6 as a novel tumor suppressor receptor that controls epithelial cell identify and restrains RAS-driven epithelial cancer.

Downregulation of 5-hydroxymethylcytosine is an early event in pancreatic tumorigenesis.

Epigenetic alterations are increasingly recognized as important contributors to the development and progression of pancreatic ductal adenocarcinoma. 5-hydroxymethylcytosine (5hmC) is an epigenetic DNA mark generated through the ten-eleven translocation (TET) enzyme-mediated pathway and is closely linked to gene activation. However, the timing of alterations in epigenetic regulation in the progression of pancreatic neoplasia is not well understood. In this study, we hypothesized that aberrant expression of ten-eleven translocation methylcytosine dioxygenase 1 (TET1) and subsequent global 5hmC alteration are linked to early tumorigenesis in the pancreas. Therefore, we evaluated alterations of 5hmC and TET1 levels using immunohistochemistry in pancreatic neoplasms (n = 380) and normal ducts (n = 118). The study cohort included representation of the full spectrum of precancerous lesions from low- and high-grade pancreatic intraepithelial neoplasia (n = 95), intraductal papillary mucinous neoplasms (all subtypes, n = 129), intraductal oncocytic papillary neoplasms (n = 12), and mucinous cystic neoplasms (n = 144). 5hmC and TET1 were significantly downregulated in all types of precancerous lesion and associated invasive pancreatic ductal adenocarcinomas compared with normal ductal epithelium (all p < 0.001), and expression of 5hmC positively correlated with expression of TET1. Importantly, downregulation of both 5hmC and TET1 was observed in most low-grade precancerous lesions. There were no clear associations between 5hmC levels and clinicopathological factors, thereby suggesting a common epigenetic abnormality across precancerous lesions. We conclude that downregulation of 5hmC and TET1 is an early event in pancreatic tumorigenesis. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cytogenetic complexity and heterogeneity in intravascular lymphoma.

AIMS: To characterise the karyotypic abnormalities and heterogeneities in intravascular lymphoma (IVL). METHODS: G-banded karyotyping was performed on biopsy specimens from a single-centre IVL cohort comprising intravascular large B-cell lymphoma (IVLBCL, n=12) and NK/T-cell lymphoma (IVNKTCL, n=1). RESULTS: Five IVLBCL cases and one IVNKTCL case (total 46%) were found to have normal karyotypes, and the cytogenetic abnormalities observed in the other seven IVLBCL cases (54%) were investigated further. These seven karyotypes were uniformly complex with an average of 13 aberrations. The seven cases all had abnormalities involving chromosome 6, with 57% involving structural abnormalities at 6q13, and chromosome 8, with 43% involving abnormalities at 8p11.2. In addition, 71% had aberrations at 19q13. On average, 4.4 chromosomal gains and losses were detected per case. Cytogenetic heterogeneities were observed in six cases (86%) and tetraploidy in three cases (43%). There was no significant difference in progression-free survival (p=0.92) and overall survival (p=0.61) between the IVLBCL cases with complex and normal karyotypes. CONCLUSION: Approximately half of IVLBCL cases had a highly heterogeneous pattern of karyotypes with different clonal numerical and structural chromosome aberrations.

Genetic variations in the human severe acute respiratory syndrome coronavirus receptor ACE2 and serine protease TMPRSS2.

AIMS: The recent emergence of novel, pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a global health emergency. The coronaviral entry requires the spike (S)-protein for attachment to the host cell surface, and employs human angiotensin-converting enzyme 2 (hACE2) for entry and transmembrane protease serine 2 (TMPRSS2) for S-protein priming. Although coronaviruses undergo evolution by mutating themselves, it is also essential to know the host genetic factors. Here, we describe the single nucleotide variations (SNVs) in human ACE2 and TMPRSS2. METHODS: The genetic variants derived from five population-sequencing projects were classified by variant type, allele frequency (AF), ethnic group and estimated pathogenicity. The SNVs in SARS-CoV-2/hACE2 contact residues were investigated. The genetic variability was normalised using non-linear regression and the total number of SNVs was estimated by the derived formulas. RESULTS: We detected 349 and 551 SNVs in ACE2 and TMPRSS2, respectively, in a total of 156 513 individuals. The vast majority (>97%) of the SNVs were very rare (AF <0.1%) and population-specific, and were computationally estimated to be more frequently deleterious than the SNVs with high AF. These SNVs were distributed throughout the coding regions; some ACE2 variants were located in the SARS-CoV-2/hACE2 contact residues, with a hemizygous state occurring in males. Using regression analysis, the total numbers of genetic variations in ACE2 and TMPRSS2 were 1.1×103 and 1.5×103, respectively, for a population of one million people. CONCLUSION: The majority of SNVs in ACE2 and TMPRSS2 are rare, population-specific and deleterious, and a multitude of very rare SNVs may explain different susceptibility to SARS-CoV-2.

Neuroendocrine carcinoma and mixed neuroendocrine‒non-neuroendocrine neoplasm of the stomach: a clinicopathological and exome sequencing study.

The gene mutation profiles of gastric neuroendocrine neoplasms are incompletely understood. The purpose of this study was to characterize the molecular pathology of poorly differentiated neuroendocrine carcinoma (NEC) and mixed neuroendocrine‒non-neuroendocrine neoplasm (MiNEN) of the stomach. Surgical cases of gastric NEC (n = 7) and MiNEN (n = 6) were examined by clinical review, immunohistochemistry, microsatellite instability (MSI) analysis and whole-exome sequencing. NEC cases consisted of small- (n = 2) and large-cell types (n = 4). All cases of MiNEN were histologically composed of large-cell type NEC and tubular adenocarcinoma. Whole-exome sequencing analysis detected recurrent mutations in TP53 in 8 cases (62%), and they were more frequently observed in MiNEN than in NEC (100% vs. 29%). Frameshift mutations of APC were observed in two cases of MiNEN. One case of large-cell type NEC had a frameshift mutation with loss of heterozygosity in RB1. The other mutated genes (e.g., ARID1 and KRAS) were detected in a single case each. A high level of MSI was confirmed in one case of MiNEN, which harbored mutations in two well-differentiated neuroendocrine tumor (NET)-related genes (MEN1 and ATRX1). In cases of MiNEN, two histological components shared mutations in TP53, APC and ZNF521, whereas alterations in CTNNB1, KMT2C, PTEN and SPEN were observed in neuroendocrine components only. In conclusion, TP53 is a single, frequently mutated gene in gastric NEC and MiNEN, and alterations in other genes are less common, resembling the mutation profiles of gastric adenocarcinomas. Gene mutations frequently observed in well-differentiated NET were uncommon but not entirely exclusive.

Multiregion whole-exome sequencing of intraductal papillary mucinous neoplasms reveals frequent somatic KLF4 mutations predominantly in low-grade regions.

OBJECTIVE: Intraductal papillary mucinous neoplasms (IPMNs) are non-invasive precursor lesions that can progress to invasive pancreatic cancer and are classified as low-grade or high-grade based on the morphology of the neoplastic epithelium. We aimed to compare genetic alterations in low-grade and high-grade regions of the same IPMN in order to identify molecular alterations underlying neoplastic progression. DESIGN: We performed multiregion whole exome sequencing on tissue samples from 17 IPMNs with both low-grade and high-grade dysplasia (76 IPMN regions, including 49 from low-grade dysplasia and 27 from high-grade dysplasia). We reconstructed the phylogeny for each case, and we assessed mutations in a novel driver gene in an independent cohort of 63 IPMN cyst fluid samples. RESULTS: Our multiregion whole exome sequencing identified KLF4, a previously unreported genetic driver of IPMN tumorigenesis, with hotspot mutations in one of two codons identified in >50% of the analyzed IPMNs. Mutations in KLF4 were significantly more prevalent in low-grade regions in our sequenced cases. Phylogenetic analyses of whole exome sequencing data demonstrated diverse patterns of IPMN initiation and progression. Hotspot mutations in KLF4 were also identified in an independent cohort of IPMN cyst fluid samples, again with a significantly higher prevalence in low-grade IPMNs. CONCLUSION: Hotspot mutations in KLF4 occur at high prevalence in IPMNs. Unique among pancreatic driver genes, KLF4 mutations are enriched in low-grade IPMNs. These data highlight distinct molecular features of low-grade and high-grade dysplasia and suggest diverse pathways to high-grade dysplasia via the IPMN pathway.

Gastric cancer following pancreaticoduodenectomy: Experience from a high-volume center and review of existing literature.

BACKGROUND: Prolonged survival of patients after pancreaticoduodenectomy can be associated with late complications due to altered gastrointestinal anatomy. The incidence of gastric cancer is increasingly reported. We set out to examine our experience with gastric cancer as a late complication after pancreaticoduodenectomy with a focus on incidence, risk factors, and outcomes. METHODS: We queried our prospectively collected institutional database for patients that developed gastric cancer after pancreaticoduodenectomy and conducted a systematic review of the literature. RESULTS: Our database revealed 6 patients who developed gastric cancer following pancreaticoduodenectomy, presenting with a mean age of 62.2 years and an even sex distribution. All of those patients underwent pancreaticoduodenectomy for malignant indications with an average time to development of metachronous gastric cancer of 8.3 years. Four patients complained of gastrointestinal discomfort prior to diagnosis of secondary malignancy. All of these cancers were poorly differentiated and were discovered at an advanced T stage (≥ 3). Only half developed at the gastrointestinal anastomosis. Four underwent surgery with a curative intent, and 2 patients are currently alive (mean postgastrectomy survival = 25.5 months). In accordance with previous literature, biliopancreatic reflux from pancreaticoduodenectomy reconstruction, underlying genetic susceptibility, and adjuvant therapy may play a causative role in later development of gastric cancer. CONCLUSION: Long-term survivors after pancreaticoduodenectomy who develop nonspecific gastrointestinal complaints should be evaluated carefully for complications including gastric malignancy. This may serve as an opportunity to intervene on tumors that typically present at an advanced stage and with aggressive histology.

Molecular characterization of organoids derived from pancreatic intraductal papillary mucinous neoplasms.

Intraductal papillary mucinous neoplasms (IPMNs) are commonly identified non-invasive cyst-forming pancreatic neoplasms with the potential to progress into invasive pancreatic adenocarcinoma. There are few in vitro models with which to study the biology of IPMNs and their progression to invasive carcinoma. Therefore, we generated a living biobank of organoids from seven normal pancreatic ducts and ten IPMNs. We characterized eight IPMN organoid samples using whole genome sequencing and characterized five IPMN organoids and seven normal pancreatic duct organoids using transcriptome sequencing. We identified an average of 11,344 somatic mutations in the genomes of organoids derived from IPMNs, with one sample harboring 61,537 somatic mutations enriched for T→C transitions and T→A transversions. Recurrent coding somatic mutations were identified in 15 genes, including KRAS, GNAS, RNF43, PHF3, and RBM10. The most frequently mutated genes were KRAS, GNAS, and RNF43, with somatic mutations identified in six (75%), four (50%), and three (37.5%) IPMN organoid samples, respectively. On average, we identified 36 structural variants in IPMN derived organoids, and none had an unstable phenotype (> 200 structural variants). Transcriptome sequencing identified 28 genes differentially expressed between normal pancreatic duct organoid and IPMN organoid samples. The most significantly upregulated and downregulated genes were CLDN18 and FOXA1. Immunohistochemical analysis of FOXA1 expression in 112 IPMNs, 113 mucinous cystic neoplasms, and 145 pancreatic ductal adenocarcinomas demonstrated statistically significant loss of expression in low-grade IPMNs (p < 0.0016), mucinous cystic neoplasms (p < 0.0001), and pancreatic ductal adenocarcinoma of any histologic grade (p < 0.0001) compared to normal pancreatic ducts. These data indicate that FOXA1 loss of expression occurs early in pancreatic tumorigenesis. Our study highlights the utility of organoid culture to study the genetics and biology of normal pancreatic duct and IPMNs. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Pattern of Invasion in Human Pancreatic Cancer Organoids Is Associated with Loss of SMAD4 and Clinical Outcome.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy characterized by extensive local invasion and systemic spread. In this study, we employed a three-dimensional organoid model of human pancreatic cancer to characterize the molecular alterations critical for invasion. Time-lapse microscopy was used to observe invasion in organoids from 25 surgically resected human PDAC samples in collagen I. Subsequent lentiviral modification and small-molecule inhibitors were used to investigate the molecular programs underlying invasion in PDAC organoids. When cultured in collagen I, PDAC organoids exhibited two distinct, morphologically defined invasive phenotypes, mesenchymal and collective. Each individual PDAC gave rise to organoids with a predominant phenotype, and PDAC that generated organoids with predominantly mesenchymal invasion showed a worse prognosis. Collective invasion predominated in organoids from cancers with somatic mutations in the driver gene SMAD4 (or its signaling partner TGFBR2). Reexpression of SMAD4 abrogated the collective invasion phenotype in SMAD4-mutant PDAC organoids, indicating that SMAD4 loss is required for collective invasion in PDAC organoids. Surprisingly, invasion in passaged SMAD4-mutant PDAC organoids required exogenous TGFß, suggesting that invasion in SMAD4-mutant organoids is mediated through noncanonical TGFß signaling. The Rho-like GTPases RAC1 and CDC42 acted as potential mediators of TGFß-stimulated invasion in SMAD4-mutant PDAC organoids, as inhibition of these GTPases suppressed collective invasion in our model. These data suggest that PDAC utilizes different invasion programs depending on SMAD4 status, with collective invasion uniquely present in PDAC with SMAD4 loss. SIGNIFICANCE: Organoid models of PDAC highlight the importance of SMAD4 loss in invasion, demonstrating that invasion programs in SMAD4-mutant and SMAD4 wild-type tumors are different in both morphology and molecular mechanism.

Intraductal pancreatic cancer is less responsive than cancer in the stroma to neoadjuvant chemotherapy.

Neoadjuvant chemotherapy (NAC) is often the treatment of choice for borderline resectable and locally advanced invasive pancreatic ductal adenocarcinoma (PDAC); however, most cancers only partially respond to therapy. We hypothesized that the location of residual neoplastic cells in resected specimens following NAC could provide a clue as to the mechanisms of resistance. PDAC cells invade the stroma but can also invade back into and spread via the pancreatic ducts, which has been referred to as "cancerization of ducts" (COD). We compared the responsiveness to chemotherapy between PDAC cells in the stroma and PDAC cells in the duct. Pancreatic resections from a total of 174 PDAC patients (NAC, n = 97; immediate surgery, n = 77) were reviewed. On hematoxylin and eosin sections, COD was identified at the same prevalence in both groups (NAC: 50/97 cases, 52%; immediate surgery: 39/77 cases, 51%; p = 0.879, Fisher's exact test). However, using quantitative image analysis of CK19 immunohistochemistry, we found that the proportion of cancer cells that were intraductal was significantly different between the NAC and immediate surgery groups (median; 12.7% vs. 1.99%, p < 0.0001, Mann-Whitney U test). This proportion was highest in patients with marked therapy responses (36.2%) compared with patients with moderate or poor responses (7.21 & 7.91%). In summary, our data suggest that intraductal components in PDAC are less responsive to chemotherapy than the remainder of the tumor, which could have important implications for therapeutic resistance.

Transcriptome complexity in intravascular NK/T-cell lymphoma.

AIMS: Intravascular NK/T-cell lymphoma (IVNKTCL) is a rare disease, which is characterised by exclusive growth of large cells within the lumen of small vessels, Epstein-Barr virus infection and somatic mutations in epigenetic regulator genes. Here, we elucidate the transcriptomic complexity of IVNKTCL. METHODS: IVNKTCL cases were retrieved from a single-centre cohort of 25 intravascular lymphomas. RNA-seq and whole exome sequencing (WES) were performed to analyse transcriptomic abnormalities and mutations in splicing factors. RESULTS: Approximately 88% of the total reads from the RNA-seq were considered exonic, while the remaining reads (12%) were mapped to intronic or intergenic regions. We detected 28,941 alternative splicing events, some of which would produce abnormal proteins rarely found in normal cells. The detected events also included tumour-specific splicing alterations in oncogenes and tumour suppressors (e.g., HRAS, MDM2 and VEGFA). WES identified premature termination mutations or copy number losses in a total of 15 splicing regulator genes, including SF3B5, SRSF12 and TNPO3. CONCLUSIONS: This study raises the possibility that IVNKTCL may be driven by multiple complex regulatory loops, including non-exonic expression and aberrant splicing, in addition to defects in epigenetic regulation.

Intravascular NK/T-cell lymphoma: clinicopathological and integrated molecular analysis of two cases provides a clue to disease pathogenesis.

AIMS: To elucidate the clinicopathological and molecular features of intravascular NK/T-cell lymphoma (IVNKTCL). METHODS: Two cases of IVNKTCL were retrieved from a single-centre cohort composed of 25 intravascular lymphomas. Whole-exome and RNA sequencing and immunohistochemistry were performed. RESULTS: We identified somatic mutations in the following epigenetic regulators: four histone genes (HIST1H2AN, HIST1H2BE, HIST1H2BN and H3F3A), histone deacetylase (HDAC5), two helicases (WRN and DDX3X), two methylation-related enzymes (TET2 and DNMT1) and the SNI/SWF pathway (ARID1A). Copy number analysis identified driver gene alterations comprising the loss of ARID1B, HACE1 and SMAD4, and the gain of SOX2 and histone clusters. RNA sequencing analysis did not indicate the presence of any fusion gene. Both cases were positive for Epstein-Barr virus (EBV) and showed strong expression of programmed death-ligand 1 (PD-L1). CONCLUSIONS: This study raises the possibility that, at least for some patients, IVNKTCL may be considered an epigenetic disease with EBV infection-associated aetiopathogenesis.

Intracholecystic Papillary Neoplasms Are Distinct From Papillary Gallbladder Cancers: A Clinicopathologic and Exome-sequencing Study.

Although intracholecystic papillary neoplasms (ICPNs) have been increasingly recognized, their features remain unclear because of the lack of standardized definition. This study aimed to elucidate clinicopathologic and genetic features of ICPNs using stringent diagnostic criteria. On the basis of the recently proposed criteria, gallbladder neoplasms showing delicate papillary growth were diagnosed as ICPNs, while polypoid papillary adenocarcinomas arranged in a complex architecture were categorized as papillary gallbladder cancers (GBCs). Clinicopathologic features were compared among ICPNs (n=7), papillary GBCs (n=24), and nonpapillary GBCs (n=44). Whole-exome and validation Sanger sequencing was also conducted. Gross mucin hypersecretion was detected in 3/7 ICPNs (43%), 1/24 papillary GBCs (4%), and 1/44 nonpapillary GBCs (2%) (P<0.001). All patients with ICPN lacked lymphovascular invasion and nodal metastasis, while these features were occasionally observed in patients with papillary or nonpapillary GBC (13% to 59%). ICPNs were less advanced than papillary and nonpapillary GBCs (P<0.001) with all cases of ICPNs being recurrence-free. Whole-exome and Sanger sequencing identified somatic mutations in STK11 (a causative gene of Peutz-Jegher syndrome; n=3), CTNNB1 (n=2), and APC (a gene of familial adenomatous polyposis; n=1) in ICPNs, while those alterations were exceptional in papillary and nonpapillary GBCs. ICPNs more commonly showed cytoplasmic and/or nuclear expressions of ß-catenin than papillary and nonpapillary GBCs. In conclusion, the histology-based classification of gallbladder papillary neoplasms is useful for identifying ICPNs that share clinicopathologic features with the pancreatic counterpart. ICPNs meeting the criteria were genetically distinct from papillary and nonpapillary GBCs, with STK11, CTNNB1, and APC being identified as major driver genes for ICPNs.

Encapsulating peritoneal sclerosis in a patient after allogeneic hematopoietic stem cell transplantation: a case report.

BACKGROUND: Encapsulating peritoneal sclerosis (EPS) is a chronic clinical syndrome of acute or subacute gastrointestinal obstruction seen mainly in patients undergoing peritoneal dialysis. Although there are a few reports on EPS developing in non-peritoneal dialysis patients, it has not been reported in patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT). Here, we report a case of EPS after a second HSCT. CASE PRESENTATION: A 46-year-old man with myelodysplastic syndrome showed relapse after HSCT and received a second HSCT. The patient was diagnosed with chronic graft-versus-host disease (cGVHD)-associated serositis because of persistent ascites. His ascites improved gradually and disappeared without immunosuppressive therapy. He presented with nausea, weight loss, and constipation 1 year after improvement of ascites. Computed tomography revealed no organic obstruction, but did reveal dilated, thickened, and adhered small bowel loops with a mass-like appearance. He was diagnosed with EPS on the basis of clinical symptoms and image findings. He received corticosteroid therapy (20 mg/body) without any improvement in symptoms. He developed recurrence of myelodysplastic syndrome at 1 month after initiation of corticosteroid therapy. This progressed into acute myeloid leukaemia after 3 months. He died 31 months after the second HSCT. At autopsy, the small and large intestines had formed extensive adhesions and showed signs of progressive fibrosis with peritoneal sclerosis, fibroblast swelling, fibrin deposition, and inflammatory cell infiltration, which confirmed the diagnosis of EPS. CONCLUSION: This case suggests that EPS may complicate patients with cGVHD-associated serositis. Although the mechanism of EPS development is not clear, clinicians should be aware of this eventuality.

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.